Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

I already tried this on some old treated pine deck boards I used to
repair portions of an exterior porch stairs. I washed and rinsed the
boards, then let them dry thoroughly. Then I painted them with an
exterior acrylic latex porch paint thinned 50/50 with distilled water.
This first coat had remarkable penetration. After it dried
thoroughly (a couple of days in 85 degree weather in the garage) I put
2 more coats of the same product, unthinned, allowing thorough drying
between coats. I used these boards to replace some worn exterior
porch stair treads, but they've only been in place for a couple of
weeks so far so I won't know the results for a couple of years.

In the past, I've used an oil primer, followed by 2 coats of latex
topcoat, but haven't had very good results. The latex bonded
tenaciously to the primer, but the primer blistered and peeled away
from the wood. This exterior application sees lots of sun, rain,
snow, and foot traffic.

oil base paint dosen't breathe so any moisture will lift the paint. latex
does so some moisture will come through without any issues. I have used
floetrol (sp) available at DD Lowes, and sherwin williams to thin it and
extend drying time (on Latex) which lets it penetrate more and although some
paints do not reccomend it I have not had a problem. Penetrol is for oil
based paints but not as easy to find
"Ether Jones" wrote in message
oups.com...

Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

I already tried this on some old treated pine deck boards I used to
repair portions of an exterior porch stairs. I washed and rinsed the
boards, then let them dry thoroughly. Then I painted them with an
exterior acrylic latex porch paint thinned 50/50 with distilled water.
This first coat had remarkable penetration. After it dried
thoroughly (a couple of days in 85 degree weather in the garage) I put
2 more coats of the same product, unthinned, allowing thorough drying
between coats. I used these boards to replace some worn exterior
porch stair treads, but they've only been in place for a couple of
weeks so far so I won't know the results for a couple of years.

In the past, I've used an oil primer, followed by 2 coats of latex
topcoat, but haven't had very good results. The latex bonded
tenaciously to the primer, but the primer blistered and peeled away
from the wood. This exterior application sees lots of sun, rain,
snow, and foot traffic.

Ether Jones writes:

Is it OK to aggressively thin latex paint with distilled water?

Isn't that ordinarily done with sprayers?

Ether Jones wrote:
Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

I already tried this on some old treated pine deck boards I used to
repair portions of an exterior porch stairs. I washed and rinsed the
boards, then let them dry thoroughly. Then I painted them with an
exterior acrylic latex porch paint thinned 50/50 with distilled water.
This first coat had remarkable penetration. After it dried
thoroughly (a couple of days in 85 degree weather in the garage) I put
2 more coats of the same product, unthinned, allowing thorough drying
between coats. I used these boards to replace some worn exterior
porch stair treads, but they've only been in place for a couple of
weeks so far so I won't know the results for a couple of years.

In the past, I've used an oil primer, followed by 2 coats of latex
topcoat, but haven't had very good results. The latex bonded
tenaciously to the primer, but the primer blistered and peeled away
from the wood. This exterior application sees lots of sun, rain,
snow, and foot traffic.


Thinning aggressively is a bad practice, you may
get the color to move into cracks but you end up
with mostly pigment and very little base to hold
the pigment to the wood. If you look at most
latex primers it says to not thin or to use a
maximum of 10 percent thinning fluid. BTW,
thinning with distilled water is overkill, any
drinkable water would be acceptable.

Latex paints don't really penetrate, they just lie
on the surface. So your idea of penetrating doing
something good is false. Paint won't fill in
cracks effectively. What you want to do is lay on
a coat that cover thoroughly to seal the wood by
coating it. If there are cracks you should be
sealing the cracks with a caulk before you paint.
Or, preferably, use sound board with no cracks.

A really good undercoat that dries on your hands
takes a lot of work to get it off, even if you
skin is oily. Your thinned paint will come off
your hands relatively easily.

What you need for a long lasting application is
not aggressive thinning, but aggressive coating.
The wood needs to be smoothed, cracks filled, and
the surface coated with a high quality porch paint.

George E. Cawthon wrote:

Thinning aggressively is a bad practice, you may
get the color to move into cracks but you end up
with mostly pigment and very little base to hold
the pigment to the wood.

Thanks for your lengthy response George. Some of your comments puzzle
me so I'd like to ask a few questions.

I don't understand your statement that I "end up with mostly pigment
and very little base to hold the pigment to the wood". If I thin
50/50, doesn't the ratio of base to pigment stay the same? In other
words, what happens to all the base? Isn't it still there, just like
the pigment is? Or is there some sort of chemical reaction where the
water destroys the base? I realize that by thinning, I don't get as
thick a coat as I would otherwise, but I figure that "something" is
better than "nothing", since the unthinned paint simply does not get
down into the fine cracks in the wood.

The cracks I am talking about are not large cracks that could be
caulked. I'm talking about many fine splits in the wood; of the order
of the thickness of a piece of paper. The unthinned paint simply
cannot get in there thoroughly, no matter how aggressively I brush it.
And, as it cures it leaves pinholes where the splits are; pinholes
where water could get in. If I thin the paint 50/50, it's still
fairly thick, but it is able to soak down into the splits instead of
just bridging over them. Then when I let it dry and paint over it with
unthinned paint, I get a continuous coating with no pinholes.

I tried scraping and washing a portion of the porch floor, then letting
it dry thoroughly and painting it with 50/50 thinned latex. You can
see the paint soak in to the fine splits, and when it dries it
absolutely doesn't rub off - it is very tenecious. I intend to cover
this first thinned coat with 2 additional coats using unthinned latex.
I'm not trying to go cheap on paint; I'm trying to get the wood coated.
Also, there are nooks and crannies in the porch where it's very
difficult to get the unthinned paint to go; a prime example is between
the deck boards. If I use unthinned paint, it wants to "bridge over"
adjacent boards instead of soaking down between them. Then, when you
walk on the boards, the slight relative motion between adjacent boards
causes the paint "bridges" to fail and expose bare wood. If I paint
these areas with thinned paint, it penetrates between the boards and
coats the hidden edges (where water drips down through). In this case,
when putting the unthinned overcoats in these areas, I would be
carefull to brush out any paint bridges.

If you look at most
latex primers it says to not thin or to use a
maximum of 10 percent thinning fluid

The label says "do not thin" but it does not say *why*. Since I
intend to thin only the first coat, and then go over it twice with
unthinned paint, I would like to understand if (and why) thinning is
still objectionable.

Or, preferably, use sound board with no cracks.

I understand that this would be optimal. In another universe I'd love
to do that. But I don't have the time or money to rip up my porch
floor. I'm constrained to work with what I have, with the wood in
place. There is no rot, but in many areas the wood is weathered, and
the paint is blistering and peeling (actually, the latex topcoat is
adhering to the primer, but the oil primer is peeling from the wood).
It's because of my unsatisfactory experience with oil primer that I am
exploring other approaches.

the surface coated with a high quality porch paint.

In the painful process of learning, I've had the "pleasure" of using
several different paints, some of them awful. The one I am using now,
and with which I am fairly impressed, is "Best Look Premium 100%
Acrylic Latex Satin Porch & Floor Enamel" from the local hardware/paint
store. It says on the fine print on the label that it's made by
Sherwin Williams. It costs about 25 bucks a gallon. It is very thick
and creamy, easy to apply, and coats very well.

clipped
In the past, I've used an oil primer, followed by 2 coats of latex
topcoat, but haven't had very good results. The latex bonded
tenaciously to the primer, but the primer blistered and peeled away
from the wood. This exterior application sees lots of sun, rain,
snow, and foot traffic.


I think label instructions are good advice, and wouldn't recommend more
thinning than the label advises, especially for high wear and outdoors.
It might work, but why tempt fate for a tough condition? Primer should
not blister unless applied to damp or dirty wood or in hot, direct sun.

Start with clean, dry wood. Scrape and sand as needed. To fill cracks
(which invite disruption of paint film and intrusion of moisture), apply
paintable, flexible caulk after primer dries. Prime the caulk after it
dries. Paint. Cover all sides of the boards.

I don't buy cheap paint, and I hate paint prep work, but I am a fanatic
about the prep when I paint or paper because I don't want to have to do
it over. Why use poor quality paint, or ruin good quality paint? Paint
stores have product specifically for thinning both types of paint and
which don't weaken the film. The logic in not thinning too much is that
you dilute to the point that you are applying little more than colored
water. Of course, it would have "remarkable" penetration. Buy some new
wood or Trex.

I use a product called Floetrol for thinning Latex paints. It also adds a
lot of good properties like helping the paint flow. This is good for doors
when you want the paint to lay flat and not have brush marks. Available
most anywhere.

Steve

Norminn wrote:

Paint stores have product specifically for thinning both types of paint and
which don't weaken the film.

"doesn't weaken the film" is the part I want to understand better. Why
doesn't this product "weaken the film" but water does? I'm not saying
you're wrong, I just want to understand how it works.


The logic in not thinning too much is that
you dilute to the point that you are applying little more than colored
water.

So... it doesn't matter if I thin the latex 50/50, as long as I apply
enough coats that the total amount of latex I use is the same as I
would have used if I didn't thin it?

For example, say I pour out two equal portions of unthinned latex into
separate containers. I paint one board with 2 coats using the first
portion (using it all up). I thin the second portion 50/50 with
distilled water, and paint the second board with that, applying coats
(and letting them dry) until the second portion is used up. Both
boards now have exactly the same amount of pigment and binder on them.
Will the paint on the second board fail because I thinned it? _Why_?
(It's the "why" part I am seeking to understand).

"Ether Jones" wrote in message
oups.com...

Norminn wrote:

Paint stores have product specifically for thinning both types of paint
and
which don't weaken the film.

"doesn't weaken the film" is the part I want to understand better. Why
doesn't this product "weaken the film" but water does? I'm not saying
you're wrong, I just want to understand how it works.


Look at the two. The product is every bit as thick as latex paint. It has
the consistency of latex paint. It has the same polymers and surfactants as
latex paint. It has added polymers and surfactants to help the paint flow
and "skin" properly. Pour a cup of it in your hand. Watch what it does.
Feel it.

Now do the same with a cup of water.

Here's yer sign.

Steve

Ether Jones wrote:
George E. Cawthon wrote:

Thinning aggressively is a bad practice, you may
get the color to move into cracks but you end up
with mostly pigment and very little base to hold
the pigment to the wood.

Thanks for your lengthy response George. Some of your comments puzzle
me so I'd like to ask a few questions.

I don't understand your statement that I "end up with mostly pigment
and very little base to hold the pigment to the wood". If I thin
50/50, doesn't the ratio of base to pigment stay the same? In other
words, what happens to all the base? Isn't it still there, just like
the pigment is? Or is there some sort of chemical reaction where the
water destroys the base? I realize that by thinning, I don't get as
thick a coat as I would otherwise, but I figure that "something" is
better than "nothing", since the unthinned paint simply does not get
down into the fine cracks in the wood.

Sure the ratio is the same but the base needs to
be a certain concentration to provide a good a
reasonable coat, that is why manufacturers caution
against thinning. You don't need to get the paint
down in those thin cracks, you just need to be
sure that the paint seals over the cracks. I
suggest that you take a good board, and paint
small sections with 100%, 90%, 70%, 50% and 40%
paint thinning with water. Then scrub a dub with
water after 24 hours. That will show what the
paint you are using will do with thinning.

The cracks I am talking about are not large cracks that could be
caulked. I'm talking about many fine splits in the wood; of the order
of the thickness of a piece of paper. The unthinned paint simply
cannot get in there thoroughly, no matter how aggressively I brush it.
And, as it cures it leaves pinholes where the splits are; pinholes
where water could get in. If I thin the paint 50/50, it's still
fairly thick, but it is able to soak down into the splits instead of
just bridging over them. Then when I let it dry and paint over it with
unthinned paint, I get a continuous coating with no pinholes.

If that is true then do it. However,you would be
much better off filling the cracks with something
other than paint, maybe glue thinned about 10
percent (use Elmers carpenter glue (the yellow
stuff). Not only will you have the cracks mostly
filled they will be glued together.


I tried scraping and washing a portion of the porch floor, then letting
it dry thoroughly and painting it with 50/50 thinned latex. You can
see the paint soak in to the fine splits, and when it dries it
absolutely doesn't rub off - it is very tenecious. I intend to cover
this first thinned coat with 2 additional coats using unthinned latex.
I'm not trying to go cheap on paint; I'm trying to get the wood coated.
Also, there are nooks and crannies in the porch where it's very
difficult to get the unthinned paint to go; a prime example is between
the deck boards. If I use unthinned paint, it wants to "bridge over"
adjacent boards instead of soaking down between them. Then, when you
walk on the boards, the slight relative motion between adjacent boards
causes the paint "bridges" to fail and expose bare wood. If I paint
these areas with thinned paint, it penetrates between the boards and
coats the hidden edges (where water drips down through). In this case,
when putting the unthinned overcoats in these areas, I would be
carefull to brush out any paint bridges.

You are trying to fix a structural problem with
paint. The board should not be moving in relation
to each other. If the boards are moving a tiny
bit you can seal with a flexible paint, but a
paint you walk on is not flexible to any extent.


If you look at most
latex primers it says to not thin or to use a
maximum of 10 percent thinning fluid

The label says "do not thin" but it does not say *why*. Since I
intend to thin only the first coat, and then go over it twice with
unthinned paint, I would like to understand if (and why) thinning is
still objectionable.

Or, preferably, use sound board with no cracks.

I understand that this would be optimal. In another universe I'd love
to do that. But I don't have the time or money to rip up my porch
floor. I'm constrained to work with what I have, with the wood in
place. There is no rot, but in many areas the wood is weathered, and
the paint is blistering and peeling (actually, the latex topcoat is
adhering to the primer, but the oil primer is peeling from the wood).
It's because of my unsatisfactory experience with oil primer that I am
exploring other approaches.

the surface coated with a high quality porch paint.

In the painful process of learning, I've had the "pleasure" of using
several different paints, some of them awful. The one I am using now,
and with which I am fairly impressed, is "Best Look Premium 100%
Acrylic Latex Satin Porch & Floor Enamel" from the local hardware/paint
store. It says on the fine print on the label that it's made by
Sherwin Williams. It costs about 25 bucks a gallon. It is very thick
and creamy, easy to apply, and coats very well.


Maybe you have the problem in hand. OTOH, the
peeling may be due to moisture absorption from
below, if the porch is over uncovered soil.

Steve B wrote:

Look at the two.

I just looked at a container of Floetrol today. Until now, I'd never
heard of it.

The product is every bit as thick as latex paint.

Very cheap latex paint maybe. Floetrol is nowhere near as thick as the
latex paints I have been using.

It has the same polymers and surfactants as latex paint. It has added polymers and surfactants to help the paint flow and "skin" properly.

How do you know this? The label on the container lists no ingredients.
The MSDS doesn't list any ingredients (it does say the boiling point
is 212F though). Where did you get your information?

Pour a cup of it in your hand. Watch what it does.
Feel it. Now do the same with a cup of water. Here's yer sign.

Do you personally find that to be a satisfying technical answer to the
question?

If I paint one board with 8 ounces of high quality latex paint, using
as many coats as it takes to use up the paint, and I paint a second
board with 8 ounces of the same high quality latex paint plus 2 ounces
of distilled water, again using as many coats as it takes to use up the
10 ounces of thinned paint, are you saying the second board has a
"weaker" film? And if so, _why_?

OT, just heard on the news - Pluto has been stripped of its planet
status.

George E. Cawthon wrote:

I suggest that you take a good board, and paint
small sections with 100%, 90%, 70%, 50% and 40%
paint thinning with water. Then scrub a dub with
water after 24 hours. That will show what the
paint you are using will do with thinning.

Good suggestion. I wasn't as scientific as you suggested with all the
different percentages, but I did run a "sanity" test before I committed
to using the thinned paint in my actual application.

I took a representative sample board and power-washed it to remove the
old blistering paint, then I let it dry and gave it a single coat of
aggressively thinned latex (I would guess 50/50 although I didn't
measure it). After letting it dry thoroughly I blasted it with the
power washer (1700 psi) and it didn't budge. So I figured, on that
basis, that using the thinned latex as a first coat, to be overcoated
with 2 coats of unthinned latex, was a reasonable thing to do. My
reason for posting here was to try to get some additional technical
reasons, if there are any, why the process I described is bad practice.
So far, to summarize what I am hearing, the gist of most of the
counter-arguments is that thinning the latex causes a thinner coat to
be applied, therefore resulting in a "weaker film". But no one so far
has suggested (at least not in clear language) that adding too much
water actually interferes with the paint's chemistry. Since I intend
to overcoat the first thinned coat with 2 coats of unthinned latex, it
seems to me that the "weakened film" argument is moot.

you would be
much better off filling the cracks with something
other than paint, maybe glue thinned about 10
percent (use Elmers carpenter glue (the yellow
stuff). Not only will you have the cracks mostly
filled they will be glued together.

This is very interesting because this is exactly the sort of thing I
wanted to do initially, because it seems to make so much sense, but I
couldn't find _anybody_ to confirm the idea, despite talking to
contractors and paint-store people. Is this really a viable approach??
Would Elmers be the right stuff to use, or might there be something
even better? It has to be water-based for this project. Is Elmer's
really paintable?

You are trying to fix a structural problem with
paint. The board should not be moving in relation
to each other.

My deck, which I built myself with 5/4" deck boards on 2x10 joists 16"
on center sitting on doubled-up 2x12 beams 6' on center supported by
posts every 5' along the beam length, you could drive a tank on it and
it wouldn't budge.

The porch is a different story. It is certainly not built as sturdily
as I would have done it myself, but it's not unlike many decks I have
walked on. The boards DO move slightly relative to one another when
you step on an area between joists. This absolutely kills the paint if
there are "paint bridges" joining the boards, as I discovered the hard
way. So when I re-paint it, I plan to avoid paint bridges between
adjacent boards.

peeling may be due to moisture absorption from
below, if the porch is over uncovered soil.

Yes, it's over uncovered soil. It is going to be very interesting to
see what happens over time to the newly-refinished treads on the rear
stairs. I discussed this in a separate post in this thread. I used a
different process on each of the 11 treads and risers.

Ether Jones wrote:
Norminn wrote:


Paint stores have product specifically for thinning both types of paint and
which don't weaken the film.


"doesn't weaken the film" is the part I want to understand better. Why
doesn't this product "weaken the film" but water does? I'm not saying
you're wrong, I just want to understand how it works.


Guess it contains the binder, so without as much heavy, ground up
pigment your paint will be as strong but with less pigment per volume.

Paint has three essential functional products (sometimes lots more
chemicals): pigment, binder, vehicle. Pigment is the color you want.
Usually ground up stuff. Binder is what holds it together when it is
dry. Vehicle is what makes it liquid enough to get from the can to the
brush to the surface, and makes it run out flat. The pigment, without
the binder (or thinned too much) would make it like milk of magnesia,
white dust on the siding )

The logic in not thinning too much is that
you dilute to the point that you are applying little more than colored
water.


So... it doesn't matter if I thin the latex 50/50, as long as I apply
enough coats that the total amount of latex I use is the same as I
would have used if I didn't thin it?

Quality paint rarely needs thinning. To thin it too much is to weaken
it's ability to stay on securely.

For example, say I pour out two equal portions of unthinned latex into
separate containers. I paint one board with 2 coats using the first
portion (using it all up). I thin the second portion 50/50 with
distilled water, and paint the second board with that, applying coats
(and letting them dry) until the second portion is used up. Both
boards now have exactly the same amount of pigment and binder on them.
Will the paint on the second board fail because I thinned it? _Why_?
(It's the "why" part I am seeking to understand).

Well, try this: take four boards, each 12" wide by four feet long. Cut
them in one foot lengths. Lay the 16 pieces of cut boards in four rows
of four. Should cover 16 square feet. Now pick them up, throw away 8
of them. Use the remaining 8 pieces to cover the same area.

Your thinned paint has binder spread too thin, I'm thinking. Might work.

Here is a link to additives, Floetrol (water base paint) and Penetrol
(oil base). Penetrol is only one I have tried, for spraying. Works
beautifully.

http://www.o-geepaint.com/cgi-bin/Fr...ww.floodco.com

Ether Jones wrote:

Steve B wrote:


Look at the two.


I just looked at a container of Floetrol today. Until now, I'd never
heard of it.


The product is every bit as thick as latex paint.


Very cheap latex paint maybe. Floetrol is nowhere near as thick as the
latex paints I have been using.


It has the same polymers and surfactants as latex paint. It has added polymers and surfactants to help the paint flow and "skin" properly.


How do you know this? The label on the container lists no ingredients.
The MSDS doesn't list any ingredients (it does say the boiling point
is 212F though). Where did you get your information?

MSDS doesn't list the chemicals, but does say that it is 90% volatile.
The other 10% is magic potion )

Norminn wrote:
Quality paint rarely needs thinning. To thin it too much is to weaken
it's ability to stay on securely.

The question on the table is, *why*. See further discussion below:

EtherJones wrote:
For example, say I pour out two equal portions of unthinned latex into
separate containers. I paint one board with 2 coats using the first
portion (using it all up). I thin the second portion 50/50 with
distilled water, and paint the second board with that, applying coats
(and letting them dry) until the second portion is used up. Both
boards now have exactly the same amount of pigment and binder on them.
Will the paint on the second board fail because I thinned it? _Why_?
(It's the "why" part I am seeking to understand).

Norminn wrote:
Well, try this: take four boards, each 12" wide by four feet long. Cut
them in one foot lengths. Lay the 16 pieces of cut boards in four rows
of four. Should cover 16 square feet. Now pick them up, throw away 8
of them. Use the remaining 8 pieces to cover the same area.

Your example is flawed; it is in no way analogous to what I wrote.
Please reread my example more carefully. In my example, there was no
binder "thrown away". Both boards have exactly the same amount of
binder (and pigment) on them. So what makes one "weaker" than the
other? Are you claiming that the added water somehow prevents the
binder from polymerizing properly? And if that is what you are
claiming, where did you learn this? Could you please cite some
technical references.

Norminn wrote:

MSDS doesn't list the chemicals, but does say that it is 90% volatile.

.... and the boiling point of that 90% is, guess what? 212 degrees F.
Does that number sound familiar?


The other 10% is magic potion )

Apparently a tightly held secret? Steve B claims they're "polymers"
and surfactants. I wonder where he got that info. Seems weird that
they would put polymers in it. You'd think they'd use monomers, like
the original latex, so it would boost the binder.

Ether Jones wrote:

I took a representative sample board and power-washed it to remove the
old blistering paint, then I let it dry and gave it a single coat of
aggressively thinned latex (I would guess 50/50 although I didn't
measure it). After letting it dry thoroughly I blasted it with the
power washer (1700 psi) and it didn't budge. So I figured, on that
basis, that using the thinned latex as a first coat, to be overcoated
with 2 coats of unthinned latex, was a reasonable thing to do.

It sounds like you've invented primer. The unknown is how long it'll
last.

Why not just use a real primer? Oil-based primer should sink in better,
but even a latex primer will have a better chance of a long life. Both
can be topcoated with latex.

--
Warren Block * Rapid City, South Dakota * USA

Warren Block wrote:
Ether Jones wrote:

I took a representative sample board and power-washed it to remove the
old blistering paint, then I let it dry and gave it a single coat of
aggressively thinned latex (I would guess 50/50 although I didn't
measure it). After letting it dry thoroughly I blasted it with the
power washer (1700 psi) and it didn't budge. So I figured, on that
basis, that using the thinned latex as a first coat, to be overcoated
with 2 coats of unthinned latex, was a reasonable thing to do.

It sounds like you've invented primer. The unknown is how long it'll
last. Why not just use a real primer? ...even a latex primer will have
a better chance of a long life.

How is latex primer chemically different from latex topcoat paint?
Does it have a different binder system than latex paint?


Oil-based primer should sink in better,

Why not oil primer for this job? Here's why:

Many claim that oil-based primer penetrates better, but the caveat is
that the wood must be BONE DRY. The least bit of moisture appears to
greatly interfere with absorption and adherence. By contrast, latex
seems to be fairly forgiving: to apply latex, the wood can't be wet or
damp, but it doesn't have to be baked dry for a week. This is a
significant issue for this outdoor project, especially at this time of
year, when finding a whole week where there is no rain and the humidity
is low and there is no dew in the morning is next to impossible.

The area to be painted is a high-use area; it is a great inconvenience
to take it out of service. If I power-wash it, I have to keep traffic
off it until it dries or it will get dirty again. For oil primer, that
means a full week of dry weather after washing. If it rains, I have to
wait another week.

Once the wood is dry and the oil primer is applied, it takes several
days to dry properly so that it can be painted with latex. If it rains
during this period it seriously compromises the primer. All during
this period, the area must be off-limits to traffic.

Once the latex is applied, I need another 24 hours of dry weather or
the latex will be compromised.


On the other hand, if I use latex:

After power-washing, the wood is ready to accept a coat of latex within
24 to 48 hours. Within 4 hours I can apply a second coat. Within 24
hours it is rain-proof and ready for foot traffic. Done.


Besides the significant inconveniences of oil (as detailed above), my
experience will oil-based primer has been highly disappointing. See my
other posts in this same thread for more details, but here is the gist
of it. I tried using latex topcoat over oil primer previously and the
system failed within one year. The latex topcoat bonded to the oil
primer, but the oil primer started blistering and peeling away from the
wood in large chunks. I tried to follow all the rules. I do not know
if I somehow did something wrong, or if oil primer just isn't the right
solution for this particular application (exterior, wood, horizontal,
foot traffic, sun, rain, snow). Some boards were coated all six
sides, and some were coated on the top and ends only. All of them
failed prematurely.

"Ether Jones" wrote in message
ups.com...

Steve B wrote:

Look at the two.

I just looked at a container of Floetrol today. Until now, I'd never
heard of it.

The product is every bit as thick as latex paint.

Very cheap latex paint maybe. Floetrol is nowhere near as thick as the
latex paints I have been using.

It has the same polymers and surfactants as latex paint. It has added
polymers and surfactants to help the paint flow and "skin" properly.

How do you know this? The label on the container lists no ingredients.
The MSDS doesn't list any ingredients (it does say the boiling point
is 212F though). Where did you get your information?

Pour a cup of it in your hand. Watch what it does.
Feel it. Now do the same with a cup of water. Here's yer sign.

Do you personally find that to be a satisfying technical answer to the
question?

If I paint one board with 8 ounces of high quality latex paint, using
as many coats as it takes to use up the paint, and I paint a second
board with 8 ounces of the same high quality latex paint plus 2 ounces
of distilled water, again using as many coats as it takes to use up the
10 ounces of thinned paint, are you saying the second board has a
"weaker" film? And if so, _why_?

OT, just heard on the news - Pluto has been stripped of its planet
status.


Let me just say this. I have used it. I like it. It works for me. Your
mileage may vary. Use it or don't. It's as good a solution as any
proposed.

Surely as good as water. Maybe even a little better.

Steve

Ether Jones wrote:
Norminn wrote:

Quality paint rarely needs thinning. To thin it too much is to weaken
it's ability to stay on securely.


The question on the table is, *why*. See further discussion below:

EtherJones wrote:

For example, say I pour out two equal portions of unthinned latex into
separate containers. I paint one board with 2 coats using the first
portion (using it all up). I thin the second portion 50/50 with
distilled water, and paint the second board with that, applying coats
(and letting them dry) until the second portion is used up. Both
boards now have exactly the same amount of pigment and binder on them.
Will the paint on the second board fail because I thinned it? _Why_?
(It's the "why" part I am seeking to understand).


Norminn wrote:

Well, try this: take four boards, each 12" wide by four feet long. Cut
them in one foot lengths. Lay the 16 pieces of cut boards in four rows
of four. Should cover 16 square feet. Now pick them up, throw away 8
of them. Use the remaining 8 pieces to cover the same area.


Your example is flawed; it is in no way analogous to what I wrote.
Please reread my example more carefully. In my example, there was no
binder "thrown away". Both boards have exactly the same amount of
binder (and pigment) on them. So what makes one "weaker" than the
other? Are you claiming that the added water somehow prevents the
binder from polymerizing properly? And if that is what you are
claiming, where did you learn this? Could you please cite some
technical references.


I thought my example was pretty good, to illustrate that the diluted
binder has fewer molecules to hang together and cover your wood. If you
want a treatise on paint chemistry, go find one. You obviously
understand factors that made your paint job fail, so why pursue methods
that aren't recommended? I do exterior painting in the fall, when
conditions are optimum for what I want to do. Dry, not too hot, not too
cold, and comfortable enough to do all the right prep work. Have
cleaned up lots of other people's sloppy work, so I consider that
valuable experience. Common sense serves better than intimate knowledge
of the chemical compounds, it seems.

Norminn wrote:
Ether Jones wrote:
Norminn wrote:

Quality paint rarely needs thinning. To thin it too much is to weaken
it's ability to stay on securely.


The question on the table is, *why*. See further discussion below:

EtherJones wrote:

For example, say I pour out two equal portions of unthinned latex into
separate containers. I paint one board with 2 coats using the first
portion (using it all up). I thin the second portion 50/50 with
distilled water, and paint the second board with that, applying coats
(and letting them dry) until the second portion is used up. Both
boards now have exactly the same amount of pigment and binder on them.
Will the paint on the second board fail because I thinned it? _Why_?
(It's the "why" part I am seeking to understand).


Norminn wrote:

Well, try this: take four boards, each 12" wide by four feet long. Cut
them in one foot lengths. Lay the 16 pieces of cut boards in four rows
of four. Should cover 16 square feet. Now pick them up, throw away 8
of them. Use the remaining 8 pieces to cover the same area.


Your example is flawed; it is in no way analogous to what I wrote.
Please reread my example more carefully. In my example, there was no
binder "thrown away". Both boards have exactly the same amount of
binder (and pigment) on them. So what makes one "weaker" than the
other? Are you claiming that the added water somehow prevents the
binder from polymerizing properly? And if that is what you are
claiming, where did you learn this? Could you please cite some
technical references.


I thought my example was pretty good, to illustrate that the diluted
binder has fewer molecules to hang together and cover your wood.

The thinned latex has exactly the same total number of molecules of
binder as the unthinned latex. Read the example again. Adding water
does not reduce the number of binder molecules, it just increases the
number of molecules of water.

Because the second portion has additional water, it is thinner and
therefore more coats will need to be applied to use it all up. But
once it's all used up, you've applied the same total number of binder
molecules to the second board as you did to the first.

If you want a treatise on paint chemistry, go find one.

I've been looking. Haven't found one yet.

You obviously understand factors that made your paint job fail,
so why pursue methods that aren't recommended?

Because I want to understand WHY they aren't recommended. I like to
understand why I'm doing what I'm doing. If the label on the paint can
says "Do not thin", I want to know why. By knowing "why", I can
determine under what circumstances it might actually be permissible,
even beneficial, to thin (even though the label says "no").


Common sense serves better than intimate knowledge
of the chemical compounds, it seems.

Common sense is good yes. But sometimes what passes for common sense
is a collection of urban legends and anecdotal experiences. That's why
it's good to ask "why". I'm not saying that's true in your case. You
seem to have some substantial experience.

A thought just occurred to me which might be germane to this
discussion. Perhaps someone familiar with how latex paint works could
comment.

My understanding is that latex paint binder consists of monomers in
water solution.

When you apply a coat of latex paint, and the water dries, the monomers
come out of solution and begin to bond together into polymers. This
bonding action forms the strong film. Once the polymers form, they are
no longer water-soluble. That's why the film is water resistant, even
though the original vehicle was water.

Now, what happens when you apply a second coat of latex? Obviously the
process repeats itself. BUT, in addition to bonding with EACH OTHER,
do the monomers in the second coat ALSO bond EQUALLY EFFECTIVELY with
the polymers in the first coat, to create one seamless film (assuming
the first coat was kept clean) ? Or, is the bonding between the
monomers of the second coat and the polymers of the first coat only
PARTIAL, so that what you get is two SEPARATE films which are bonded
together, but the bond BETWEEN the two coats is not as strong as the
bond WITHIN each coat?

If the latter is true, it would explain the difference between boards
one and two in the example I gave in an earlier post. The first and
second boards would have the exact same total film thickness, but the
first board would have fewer, thicker layers; and the second board
would have more, thinner, layers. What this means in practical terms
as far as the quality of the paint job is still arguable I suppose.

Ether Jones wrote:
A thought just occurred to me which might be germane to this
discussion. Perhaps someone familiar with how latex paint works could
comment.

My understanding is that latex paint binder consists of monomers in
water solution.

When you apply a coat of latex paint, and the water dries, the monomers
come out of solution and begin to bond together into polymers. This
bonding action forms the strong film. Once the polymers form, they are
no longer water-soluble. That's why the film is water resistant, even
though the original vehicle was water.

Now, what happens when you apply a second coat of latex? Obviously the
process repeats itself. BUT, in addition to bonding with EACH OTHER,
do the monomers in the second coat ALSO bond EQUALLY EFFECTIVELY with
the polymers in the first coat, to create one seamless film (assuming
the first coat was kept clean) ? Or, is the bonding between the
monomers of the second coat and the polymers of the first coat only
PARTIAL, so that what you get is two SEPARATE films which are bonded
together, but the bond BETWEEN the two coats is not as strong as the
bond WITHIN each coat?

If the latter is true, it would explain the difference between boards
one and two in the example I gave in an earlier post. The first and
second boards would have the exact same total film thickness, but the
first board would have fewer, thicker layers; and the second board
would have more, thinner, layers. What this means in practical terms
as far as the quality of the paint job is still arguable I suppose.

I don't know anthing about monomers and polymers. By your description,
thinning the paint too much with water keeps the molecules from bonding
because they are spread too far apart. Reason I used the cut boards
(molecules of paint binder) example - you can't cover the same area with
half the material, whether microscopic or macroscopic. Capiche?

The boards you refinished likely had some moisture in them, having been
washed two days before. Not washed, but without impermeable finish,
they would be damp from being outdoors. Boards fastened onto a deck,
without being finished on all sides, would hold moisture. So, when
finish is applied, sun hits the deck, the moisture expands and the paint
film blisters or cracks.

"Ether Jones" wrote in message
oups.com...

Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

The best technical explanation is simply that there are products made
specifically to do that, and they are going to do a better job than using
water.

"Ether Jones" wrote in message
ups.com...

The cracks I am talking about are not large cracks that could be
caulked. I'm talking about many fine splits in the wood; of the order
of the thickness of a piece of paper. The unthinned paint simply
cannot get in there thoroughly, no matter how aggressively I brush it.
And, as it cures it leaves pinholes where the splits are; pinholes
where water could get in.

What you're looking for is a "block filler" paint/primer.

"Ether Jones" wrote in message
oups.com...

Norminn wrote:

Paint stores have product specifically for thinning both types of paint
and
which don't weaken the film.

"doesn't weaken the film" is the part I want to understand better. Why
doesn't this product "weaken the film" but water does? I'm not saying
you're wrong, I just want to understand how it works.

Because it IS film. i.e. part of the binder. But it flows better. Anyway,
to fill cracks and other small imperfections, buy a paint specifically for
the job. Sherwin Williams sells PrepRite High Build Primer/Surfacer, or
even Block Filler (which is meant for concrete, I don't know how well it
would work on wood). Other companies probably have similar things.

jeffc wrote:
"Ether Jones" wrote in message
oups.com...

Norminn wrote:

Paint stores have product specifically for thinning both types of paint
and
which don't weaken the film.

"doesn't weaken the film" is the part I want to understand better. Why
doesn't this product "weaken the film" but water does? I'm not saying
you're wrong, I just want to understand how it works.

Because it IS film. i.e. part of the binder.

No disagreeing with you, but where did you get this information? There
is no information on the product label, and the MSDS lists no
ingredients at all.


But it flows better. Anyway,
to fill cracks and other small imperfections, buy a paint specifically for
the job. Sherwin Williams sells PrepRite High Build Primer/Surfacer, or
even Block Filler (which is meant for concrete, I don't know how well it
would work on wood). Other companies probably have similar things.

I have looked and looked, and asked many contractors and paint store
gurus, and no one has been able to recommend such a product for the
application at hand. Remember, this application is for exterior,
horizontal, previously painted, weathered, wood, exposed to sun, rain,
snow, and heavy foot traffic. If anyone knows of a specific product
name and manufacturer for a product like jeffc has mentioned, please
post it.

jeffc wrote:
"Ether Jones" wrote in message
oups.com...

Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

The best technical explanation is simply that there are products made
specifically to do that, and they are going to do a better job than using
water.

Well no offense jeffc, but that's certainly not a technical explanation
and not very helpful.

BUT... if you find answers like that satisfying, more power to you.
Vive la difference.

"Ether Jones" wrote


No disagreeing with you, but where did you get this information? There
is no information on the product label, and the MSDS lists no
ingredients at all.

Just do what I did. I wrote to the company and asked them to please send me
the private patent information that contains all their ingredients and trade
secrets. They sent them to me immediately.

Steve

"Ether Jones" wrote in message
oups.com...

jeffc wrote:
"Ether Jones" wrote in message
oups.com...

Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

The best technical explanation is simply that there are products made
specifically to do that, and they are going to do a better job than using
water.

Well no offense jeffc, but that's certainly not a technical explanation
and not very helpful.

BUT... if you find answers like that satisfying, more power to you.
Vive la difference.


I guess I'm stupid. I totally understood what Jeff was saying. I do the
same things when traveling by airplane, going over a bridge, or turning on
the lights.

I really don't have to understand everything that makes them work, and I
sure couldn't explain it to a Piled High and Deep type of person in a
conversation, but then, I'm just one of those stupid nontechnical types.

Steve

Ether Jones wrote:
jeffc wrote:

"Ether Jones" wrote in message
groups.com...

Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

The best technical explanation is simply that there are products made
specifically to do that, and they are going to do a better job than using
water.


Well no offense jeffc, but that's certainly not a technical explanation
and not very helpful.

BUT... if you find answers like that satisfying, more power to you.
Vive la difference.


This thread has a distinct odor of troll .. why don't you take your vast
scientific conversation to a paint chemist at a paint company? The
whole idea behind paint is to keep wood from getting split, cracked and
weathered, so we yokels on ahr share our experience to try to help
others. Paint products that I am familiar with say "don't thin more
than 10%", "sand weathered wood", "apply to clean, dry surface", "prime
bare wood", etc. Since painting is a good deal of work, the preparation
being the most tedious, we haul out the brushes and tarps and get the
job done before the item to be protected turns to crap. You have been
offered good faith advice, but challenge everyone who replies. By the
time you get around to doing the project, the house will be falling down.

Ether Jones wrote:

BUT... if you find answers like that satisfying, more power to you.
Vive la difference.

just paint the ****ing board and stop ****in around

you coulda been done by now
damn nickel holding up a dollar

you sure don't ask for much for nothing do you

you're a real pill

"it puts the brush into the paint and paints the board"

"PAINT THE ****ING BOARD"

You should be using Decking products, following instructions and not
making up your own with the wrong product. Your past failures might be
the wrong product, prep or aplication on a hot or damp surface. Get and
use products designed for the job and do what they say.

yeeha wrote:

Ether Jones wrote:


BUT... if you find answers like that satisfying, more power to you.
Vive la difference.


just paint the ****ing board and stop ****in around

you coulda been done by now
damn nickel holding up a dollar

you sure don't ask for much for nothing do you

you're a real pill

"it puts the brush into the paint and paints the board"

"PAINT THE ****ING BOARD"

I didn't want to be the first to use the "f" word, but, yeah. )

"m Ransley" wrote in message
...
You should be using Decking products, following instructions and not
making up your own with the wrong product. Your past failures might be
the wrong product, prep or aplication on a hot or damp surface. Get and
use products designed for the job and do what they say.


That may work for some here, but others insist that a person totally
understand and comprehend what the paint is doing, why, and all the
ingredients of said paint.

IOW, they do more thinking than painting.

Steve

m Ransley wrote:
You should be using Decking products, following instructions and not
making up your own with the wrong product. Your past failures might be
the wrong product, prep or aplication on a hot or damp surface. Get and
use products designed for the job and do what they say.

Most decking products are stains, not paint. Unfortunately, I'm
constrained to use paint since the former owner painted the entire
porch and I want it to match. Only the breezeway area (about 150
square feet) and steps need refinishing.

Two years ago, I essentially followed the advice you recommended above.
The result was unsuccessful, despite scrupulously following the label
instructions. I think I posted the details elsewhere in this thread.
The paint started to fail after one year. I still don't know why for
sure, although many here have suggested possible reasons, and the oil
primer seems to be the likely culprit, even though "latex over oil
primer" is the conventional wisdom.

Some folks say "paint all six sides", others say "no, leave the
underside unpainted so the wood can breathe". I tried both ways and
they both failed (six sides on the steps, only the top in the breezeway
area).

Some folks say "use oil", others say "no, oil is too brittle and
moisture-impermeable and will crack and separate from the wood as the
wood expands and contracts due to moisture". I used latex over oil
primer, as recommended on the latex label. Perhaps the "oil is too
brittle" folks are right. That's my current working hypothesis at any
rate.

So this summer I tried a different approach.

One set of steps I pressure washed to blast off as much blistering
paint as possible. Let it dry and sanded it, then applied the latex
with no oil primer. The latex is a high quality 100% acrylic latex
paint rated for exterior horizontal surfaces exposed to foot traffic
and weather. On half the steps I applied the latex unthinned (as per
label directions), on the other half I used thinned latex for the first
coat (in order to penetrate better into hairline cracks and the spaces
between the boards) and then 2 coats of unthinned.

On the other set of steps I removed all the treads and risers, and
completely removed all previous coating with a planer, edger, and belt
sander. I used a different approach on each of the 12 boards,
including replacing some of the boards with new wood; but in all cases
I coated all six sides (that's why I removed the boards). For example,
on one of the boards I applied the latex directly to the wood without a
primer. On another I used thinned latex as the first coat, then 2
coats of unthinned latex over that. On another I stained the board
first with Cabot semi-solid deck stain, then applied latex over that
(yes, I know that conventional wisdom says don't do this). On another
I used an oil-based water-sealing product which claimed it was
paintable, then oil-primed and latex topcoat over that (letting each
dry thoroughly of course). I kept a record of how each board was
prepared. In a couple of years I'll see the results. Hopefully, at
least one approach will endure.

I haven't re-done the breezeway area yet, but the plan is to do it the
same way as the first set of steps mentioned above (power-wash to
remove blistering paint, then apply latex without oil primer).
Removing the breezeway boards to paint the undersides and edges and
ends is out of the question. Using oil in this area is extremely
inconvenient - after power washing, the waiting period for proper
drying would be a real problem. Oil requires absolutely bone-dry
wood. Any moisture stops the penetration. Latex is far more forgiving
in this regard.

The one question that remains unanswered, and the one that has offended
and/or angered some posters to this thread, is the issue of thinning
latex paint with water. I was hoping there might be an old-timer or
two here who understood this issue and could shed some light:

Many latex paint labels say "do not thin". The question I was
exploring is whether this "do not thin" exhortation is universally
true, or whether there might be extenuating circumstances wherein in
would be permissible, even beneficial, to thin just the first coat, to
improve penetration into nooks and crannies and spaces between boards,
as long as an unthinned second (or even third) coat of unthinned is
applied.

I tried to find a suitable water-based primer for this application but
was unsuccessful. I looked at MANY paint stores and home-improvement
centers, and spoke with a few contractors and painter friends. I have
yet to find a water-based primer that is rated for horizontal wood
surfaces exposed to rain and foot traffic. One guy swore by Zinser
123, so I bought a gallon, but when I got home and read all the fine
print, it categorically stated "not for use on horizontal surfaces
exposed to foot traffic and water".

I've also read that you should always use a primer and topcoat from the
same manufacturer to assure they are compatible. I'm not sure if this
is true, or if true, why.

If anyone knows of a water-based primer designed for use on
previously-painted weathered wood which has been power-washed to clean
it and remove loose paint, and which is compatible with
Sherwin-Williams 100% acrylic latex exterior porch and floor paint,
please post.

Ether Jones wrote:
Is it OK to aggressively thin latex paint with distilled water? My
aim in doing so is NOT to increase coverage, but rather to improve the
penetration into splits and cracks and rough areas. My intent would
be to allow this first thinned coat to soak in and dry thoroughly, then
apply two more coats of the same product, unthinned.

If the answer is "no", could you please give some technical explanation
why it is not a good idea.

I think I've finally found a (partial) answer to my question; I'll post
it here for the benefit of anyone else who might be interested:

The major solvent in today's latex paints is water. But they also
contain small amounts of organic solvents, such as 2-(2 butoxyethoxy)
ethanol and trimethylpentanediol isobutyrate, which function as
"coalescing solvents". These coalescing solvents play an important
role in the film formation, and apparently the RATIO of organic solvent
to water affects the film formation. At least that's what the
technical discussion in the link below appears to be saying. SO... the
reason why adding too much water could be a bad idea is NOT that there
is "less binder" in the thinned latex, but rather that the thinned
latex has the wrong ratio of water-to-organic-solvent... and this
apparently affects the chemistry of the film formation process.

more details at this link:
http://www.dow.com/ucarlatex/coating...chive/0311.htm

The proof is in the pudding, though, I suppose. Yesterday I blasted
the breezeway area of the porch with the power washer. Large sheets
and small flakes of old paint were flying everywhere. But the test
patches where I had applied thinned latex to scraped-bare wood 3 days
prior held fast and showed no sign at all of coming loose or wearing
off. So the plan is to use thinned latex for the first coat to
penetrate into hard-to-reach places (like between adjacent deck boards,
and where railing posts sit on the deck boards, and hairline splits in
the boards); and topcoat that twice with unthinned. I'll know by next
year if this approach is better than the latex-over-oil-primer approach
I used 2 years ago which failed in one year.

Thanks to all those who contributed.

Just add some mineral spirits. Whats so hard about that.
Gasoline works too.

NickySantoro wrote:

For your situation the most effective procedure is to use a slow
drying oil based primer thinned slightly, allowing it to dry
thoroughly, then topcoating with the finish of choice.

Can you recommend a specific brand and model of primer, which is
explicitly rated for exterior wood floor and steps?

NickySantoro wrote:
On 29 Aug 2006 17:22:09 -0700, "Ether Jones"
wrote:
I'll know by next
year if this approach is better than the latex-over-oil-primer approach
I used 2 years ago which failed in one year.


If it failed it was due to causes as yet unrevealed, likely improper
application or inadequate surface preparation.

Perhaps, but the application and prep were meticulous. All treads and
risers were removed and thoroughly scraped, wire-brushed, sanded, and
brushed. Primed with oil primer all six sides. Top-coated with 2
coats of porch and floor latex all six sides.

So the other possibility is perhaps the conventional wisdom of latex
topcoat over oil primer is not universally correct for all
applications. FWIW, I spent 30 minutes in a paint store this afternoon
reading the label of each and every different exterior primer, both oil
and latex (8 or so different cans). Not a single one of them listed
exterior wood floors or steps as an acceptable application. Some of
the highly-touted brands such as Zinser 123 and Kilz explicitly
excluded exterior wood floors and steps.

It will take a couple of years, but my experiment with the backyard
porch steps should be most interesting:

http://groups.google.com/group/alt.h...&output=gplain