My tiling book says to sand the concrete with a coarse grit sandpaper
and then wash with muriatic acid. A friend of mine thinks muriatic
acid is way overkill and just washing the floor would suffice. I'd
rather avoid using the stuff. Any thoughts?

(BTW, concrete is interior slab...seems smooth. Troweled surface?)

"Greg Esres" wrote in message
oups.com...
My tiling book says to sand the concrete with a coarse grit sandpaper
and then wash with muriatic acid. A friend of mine thinks muriatic
acid is way overkill and just washing the floor would suffice. I'd
rather avoid using the stuff. Any thoughts?

(BTW, concrete is interior slab...seems smooth. Troweled surface?)


The purpose of the acid is not to clean the floor but to etch the surface
for a better bond. I don't know if it's necessary for tiling but I can tell
you it sure is for painting. When in doubt, follow the instructions and
ventilate as much as possible.

Steve.

SteveF wrote:
purpose of the acid is not to clean the floor but to etch the surface
for a better bond. I don't know if it's necessary for tiling but I
can tell you it sure is for painting. When in doubt, follow the
instructions and ventilate as much as possible.

Good advice, thank you.

On Jan 26, 11:46 am, "Greg Esres" wrote:
SteveF wrote:purpose of the acid is not to clean the floor but to etch the surface
for a better bond. I don't know if it's necessary for tiling but I
can tell you it sure is for painting. When in doubt, follow the
instructions and ventilate as much as possible.

Good advice, thank you.

Don't forget to dilute the acid at least 5 to 1 with water. % parts
water to 1 part acid and then rinse well.

Don't forget to dilute the acid at least 5 to 1 with water. % parts
water to 1 part acid and then rinse well.

I am concerned about thoroughly rinsing; it's not like a porch that I
can hose off. This is in the middle of my house. I was thinking of
mixing some baking soda in with the rinse water.

"Greg Esres" wrote in message
oups.com...
Don't forget to dilute the acid at least 5 to 1 with water. % parts
water to 1 part acid and then rinse well.

I am concerned about thoroughly rinsing; it's not like a porch that I
can hose off. This is in the middle of my house. I was thinking of
mixing some baking soda in with the rinse water.


The times I've done it I just put down some water and sucked it up with my
shop vac. Repeat (and repeat and repeat) until all the areas have been
rinsed a couple times. I've not used anything other than water.

Steve.

The times I've done it I just put down some water and sucked it up
with my
shop vac. Repeat (and repeat and repeat) until all the areas have been

rinsed a couple times.

Ah, good idea!

You know, the shop vac has got to be my favorite tool. ;-)

Thanks for the ideas!

Greg Esres writes:

I am concerned about thoroughly rinsing; it's not like a porch that I
can hose off. This is in the middle of my house. I was thinking of
mixing some baking soda in with the rinse water.

What's the issue with rinsing? Concrete is very alkaline and will
neutralize any HCl residue if you scrub it in and then sponge it up.

On 25 Jan 2007 17:42:46 -0800, "Greg Esres" wrote:

My tiling book says to sand the concrete with a coarse grit sandpaper
and then wash with muriatic acid. A friend of mine thinks muriatic
acid is way overkill and just washing the floor would suffice. I'd
rather avoid using the stuff. Any thoughts?

(BTW, concrete is interior slab...seems smooth. Troweled surface?)

I'd try to find an alternative.

Muriatic is (or turns to) Sulfuric (or is it Hydorchloric?) acid.
For a small job, it might be manageable. For major square footage,
it can get out of hand. Truly Nasty Stuff.

If you gotta do it, take muy mucho serious precautions. The
fumes are toxic. You could get a surface coat of rust on
any iron-based materials in the area.

And, yeah, after it's done it's work, baking soda or
any lye compound will help neutralize the acidity.

Good Luck,
Puddin'

"Life is nothing but a competition to be the criminal rather
than the victim."
- Bertrand Russell

Muriatic is (or turns to) Sulfuric (or is it Hydorchloric?) acid.
For a small job, it might be manageable. For major square footage,
it can get out of hand. Truly Nasty Stuff.


Muriatic acid is usually about 32% hydrochloric acid, and
the rest water. Hydrochloric acid is essence of vomit.

It's a real acid. *I* wouldn't have called it "truly nasty",
but you do want to treat it with respect.

Greg Esres wrote:

My tiling book says to sand the concrete with a coarse grit sandpaper
and then wash with muriatic acid. A friend of mine thinks muriatic
acid is way overkill and just washing the floor would suffice. I'd
rather avoid using the stuff. Any thoughts?

(BTW, concrete is interior slab...seems smooth. Troweled surface?)

Nuts! We didn't even wash ours. Just tore up the carpet, vacuumed, and
the contractor did the rest. No suggestion made as to cleaning it. Is
it bare concrete? In living area?

"Greg Esres" wrote in message
ups.com...
The times I've done it I just put down some water and sucked it up
with my
shop vac. Repeat (and repeat and repeat) until all the areas have been

rinsed a couple times.

Ah, good idea!

You know, the shop vac has got to be my favorite tool. ;-)

Thanks for the ideas!


Here's another one - take out the filter first and make a splash guard to
keep water out of the motor so you don't soak the filter as they cost about
half the cost of the vac.

Steve.

Norminn wrote:

Is it bare concrete? In living area?

Underneath the carpet, yes.

If you gotta do it, take muy mucho serious precautions

Wilco, thank you.

What's the issue with rinsing? Concrete is very alkaline and will
neutralize any HCl residue if you scrub it in and then sponge it up.

I'm not sure exactly....the directions are a bit vague about the
penalties for not rinsing. Perhaps it is remnants of the chemical
reaction that need to be cleaned out, rather than the chemical itself.
I do have this mental images of it eating through my foundation,
though. ;-)

don't soak the filter as they cost about half the cost of the vac.

I have an old one that is covered with joint compound that I could use.
I was going to try to clean it, but this might be a better use of that
resource.

Greg Esres wrote:
Norminn wrote:

Is it bare concrete? In living area?

Underneath the carpet, yes.

Does your book recommend muriatic acid on the concrete for all
installations, or only for special conditions? What concentration?
I have used muriatic once, on concrete, outdoors, per label, in
preparation for sealing a deck. It is NOT something I would even
consider using inside my home.

Greg Esres writes:

Perhaps it is remnants of the chemical
reaction that need to be cleaned out, rather than the chemical itself.


As I said, sponge it up well. Or puddle some rinse water and squeegee it
off. Or use a wet extraction carpet cleaner.

"Greg Esres" wrote in message
ups.com...
What's the issue with rinsing? Concrete is very alkaline and will
neutralize any HCl residue if you scrub it in and then sponge it up.

I'm not sure exactly....the directions are a bit vague about the
penalties for not rinsing. Perhaps it is remnants of the chemical
reaction that need to be cleaned out, rather than the chemical itself.
I do have this mental images of it eating through my foundation,
though. ;-)




the acid wash
leaves a chalky residue when it dries if your painting over concrete
you need to remove this residue so the paint will bond to the concrete.
(I am assuming your going to paint)

"Mike" wrote in message
. ..

"Greg Esres" wrote in message
ups.com...
What's the issue with rinsing? Concrete is very alkaline and will
neutralize any HCl residue if you scrub it in and then sponge it up.

I'm not sure exactly....the directions are a bit vague about the
penalties for not rinsing. Perhaps it is remnants of the chemical
reaction that need to be cleaned out, rather than the chemical itself.
I do have this mental images of it eating through my foundation,
though. ;-)




the acid wash
leaves a chalky residue when it dries if your painting over concrete
you need to remove this residue so the paint will bond to the concrete.
(I am assuming your going to paint)

Ha I guess I should have paid attention to the subject.

as Rosanna Rosannadanna says " Nevermind"

Does your book recommend muriatic acid onthe concrete for all
installations, or only for special conditions?

It says if the surface is smooth. 1:4 ratio.

Ha I guess I should have paid attention to the subject.

I was wondering if I was supposed to paint before applying the
thinset... ;-)

I'm not sure exactly....the directions are a bit vague about the
penalties for not rinsing. Perhaps it is remnants of the chemical
reaction that need to be cleaned out, rather than the chemical itself.
I do have this mental images of it eating through my foundation,
though. ;-)

the acid wash
leaves a chalky residue when it dries if your painting over concrete
you need to remove this residue so the paint will bond to the concrete.
(I am assuming your going to paint)

Seems as if it ought to leave salt. (Calcium chloride?)

On Sat, 27 Jan 2007 02:44:59 GMT, Norminn wrote:

Greg Esres wrote:
Norminn wrote:

Is it bare concrete? In living area?

Underneath the carpet, yes.

Does your book recommend muriatic acid on the concrete for all
installations, or only for special conditions? What concentration?
I have used muriatic once, on concrete, outdoors, per label, in
preparation for sealing a deck. It is NOT something I would even
consider using inside my home.

That was my take on it. But I tested a few square feet on
basement floor. Not for me, and I got no wife, no kids.

Much less dangerous outdoors (if you stay down-wind).

Do they still tile etc basement floors in new houses?
Do they first treat with acid? My guess is "Not".

Sounds like the OP needs an experienced flooring
guy for a consult. Match the right adhesive with
his floor. I just went out and bought name-brand
adhesive years ago and regretted it.

Good Luck,
Puddin'

"Life is nothing but a competition to be the criminal rather
than the victim."
- Bertrand Russell

On Fri, 26 Jan 2007 19:20:54 -0500, "SteveF" wrote:


"Greg Esres" wrote in message
oups.com...
The times I've done it I just put down some water and sucked it up
with my
shop vac. Repeat (and repeat and repeat) until all the areas have been

rinsed a couple times.

Ah, good idea!

You know, the shop vac has got to be my favorite tool. ;-)

Thanks for the ideas!


Here's another one - take out the filter first and make a splash guard to
keep water out of the motor so you don't soak the filter as they cost about
half the cost of the vac.

The pleated filters are expensive, but the paper filters are much
cheaper. For Shop-Vac brand walmart has a bag of 3 with no plastic
ring, if you have the ring. Other stores, like Lowes, sell the
filters with a plastic ring, for a little more, which** you need to
hold the filter to the cage. Although I agree that perhaps the side
of the cage near the input hole could be covered to keep the muritic
acid out of the motor. You have to leave the other side open or it
won't suck.

**HD sells another brand that might not be the same size, I forget,
but it uses a big rubber band iirc. The rubber band is smaller when
not using it, but rubber bands can wear out or dry out and I already
have the plastic ring.

Steve.

Update on old thread:

Turns out the thinset I bought (MAPEI) says that acid etching is "not
recommended". I've found the same recommendation (or non-
recommendation) on similar products. My tiling book information
appears unreliable.