Hello,

I'm getting ready to plaster over two former doorways, and I'm looking
for any advice, suggestions, or things to avoid. The walls are 1910
wood lath and plaster, and I'm patching them with salvaged wood lath
to match. I've flipped the wood lath so the cleaner side is exposed.
On top of that I'm going to use a Structo-Lite basecoat, and then
Diamond brand veneer plaster, since the Structo-Lite says to use a
finish plaster containing lime.

My basic game plan: soak the wood lath the night before, spray the
lath with water before the basecoat, apply the basecoat 1/16"-3/32"
shy of the surrounding plaster, let the basecoat set but not dry (~2
hours at 65 F and 65% RH), apply the finish plaster, smooth with a 42"
darby to match the surrounding plaster.

How should I treat the joints between the old and new plaster? I'm
thinking of undercutting the old plaster a little. Any other
suggestions or advice?

Thanks,
Wayne

"Wayne Whitney" wrote in message
...
Hello,

I'm getting ready to plaster over two former doorways, and I'm looking
for any advice, suggestions, or things to avoid. The walls are 1910
wood lath and plaster, and I'm patching them with salvaged wood lath
to match. I've flipped the wood lath so the cleaner side is exposed.
On top of that I'm going to use a Structo-Lite basecoat, and then
Diamond brand veneer plaster, since the Structo-Lite says to use a
finish plaster containing lime.

My basic game plan: soak the wood lath the night before, spray the
lath with water before the basecoat, apply the basecoat 1/16"-3/32"
shy of the surrounding plaster, let the basecoat set but not dry (~2
hours at 65 F and 65% RH), apply the finish plaster, smooth with a 42"
darby to match the surrounding plaster.

How should I treat the joints between the old and new plaster? I'm
thinking of undercutting the old plaster a little. Any other
suggestions or advice?

Thanks,
Wayne

I sure would not spray the lath with water. Once the wall is sealed you will
have moisture in there and it will take a long time for it to find a way
out.

You might try a router and chamfer the edge, 45 degrees. You will need a
large knife to make the joint go away. Not a job for me. I suck at taping.
Other wise sounds good to me.

In article KyE8c.45571$Bg.33627@fed1read03, SQLit wrote:

I sure would not spray the lath with water. Once the wall is sealed
you will have moisture in there and it will take a long time for it
to find a way out.

Well, in my case, the other side of the wall is open, so the moisture
will get out. That side will get blueboard and veneer plaster later.

In any event, I'm told you have to wet the wood lath, otherwise it
will suck all the moisture out of the plaster and interfere with the
setting. The plaster is wet anyway, so the additional moisture should
be fine.

Cheers, Wayne

Drywall it, its alot easier

I think I would have used metal lath. You have already used the
wood. Yes, wet the wood. Have you plastered before? Quite a
learning curve. Most beginners make the plaster too stiff. It
should be soft like Cool Whip. Peanut butter is too stiff.

Most plaster work is a three step process. Base coat, well keyed
to the lath, no thought of depth. The Structolite is an excellent
product. This coat is called the scratch coat. It is normal to
use a plaster tine to literally put scratch lines in the wet
plaster to help key the second coat. It sounds as if you are
trying to get the whole thing done in an afternoon. It would
probably be more normal to allow the base coat to dry overnight.
You may have read about some minimum dry time. If you have not
plastered before, I think you will rather let it dry overnight.

The second coat is called a brown coat. It is important again to
wet the substrate and apply the coat with good pressure. This is
the one where you worry about getting up to the proper depth for
the finish. It is possible to combine scratch and brown with the
Structolite, but if the existing plaster is about 3/4" thick, you
will have a lot of shrinkage cracking and you will have some
trouble getting both a good key and a heavy fill. Try to keep the
brown coat down a 1/16 to and 1/8. As the plaster sets, make sure
you rake out the edges. It would be better that the edges be too
deep, rather than too shallow. I think you may be better off
letting it dry overnight

What finish are you trying for? Most walls were sand finish, some
cork. This is where you will have the most difficulty, blending
the finish to the existing. If it is sand finish, you will need a
very soft sponge float - not the hard red rubber one from the
concrete department. Cork and cedar shingle give different
finishes. The sponge will usually be yellow or green. I would
not shift to lime plaster unless you need a slick finish, and even
then you can use the Struclolite with more effort. Structokite
gives a very forgiving sand finish. Again wet the substrate!!!!
Apply the plaster with the normal hard trowel using good pressure.
Strike the finish with your straight edge. You will need a flip
brush to keep the surface continually wet once you start to work
the sponge float in a circular motion. Work the edges well. Be
careful not to undercut the fresh plaster at the edges. If the
finish is over an 1/8, it will probably develop shrinkage cracks.

I think you should make up some Structolite and apply it to a
piece of scrap sheetrock, looking for the finish. It will give
you some experience. The finish is what will make or break the
project.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing. . . .
DanG


"Wayne Whitney" wrote in message
...
Hello,

I'm getting ready to plaster over two former doorways, and I'm
looking
for any advice, suggestions, or things to avoid. The walls are
1910
wood lath and plaster, and I'm patching them with salvaged wood
lath
to match. I've flipped the wood lath so the cleaner side is
exposed.
On top of that I'm going to use a Structo-Lite basecoat, and
then
Diamond brand veneer plaster, since the Structo-Lite says to use
a
finish plaster containing lime.

My basic game plan: soak the wood lath the night before, spray
the
lath with water before the basecoat, apply the basecoat
1/16"-3/32"
shy of the surrounding plaster, let the basecoat set but not dry
(~2
hours at 65 F and 65% RH), apply the finish plaster, smooth with
a 42"
darby to match the surrounding plaster.

How should I treat the joints between the old and new plaster?
I'm
thinking of undercutting the old plaster a little. Any other
suggestions or advice?

Thanks,
Wayne

"Wayne Whitney" wrote in message
...
Hello,

I'm getting ready to plaster over two former doorways, and I'm looking
for any advice, suggestions, or things to avoid. The walls are 1910
wood lath and plaster, and I'm patching them with salvaged wood lath
to match. I've flipped the wood lath so the cleaner side is exposed.
On top of that I'm going to use a Structo-Lite basecoat, and then
Diamond brand veneer plaster, since the Structo-Lite says to use a
finish plaster containing lime.

My basic game plan: soak the wood lath the night before, spray the
lath with water before the basecoat, apply the basecoat 1/16"-3/32"
shy of the surrounding plaster, let the basecoat set but not dry (~2
hours at 65 F and 65% RH), apply the finish plaster, smooth with a 42"
darby to match the surrounding plaster.

How should I treat the joints between the old and new plaster? I'm
thinking of undercutting the old plaster a little. Any other
suggestions or advice?

Thanks,
Wayne

Hi,
The advise about two separate under-coats and adequate curing time is right
on. I would go one step further, and fit wire lath right over the wood,
laying it tightly (no raised areas), as this will be more forgiving of lousy
technique and consistency.
Undercut the adjacent edges of the old plaster. Brush on some "Link" bonding
agent. Float the brown coat very smooth (keep working it, trowel it hard).
Unless you want to punish yourself forget the white coat, and use durabond
90 (or even plain drywall mud) for the finish coat. Learning to use "lime
putty, guaging plaster and retarder" is too much for occasional
weekend-warrior-type people (myself included). And if you don't use those
three materials, I would predict a lot of white plaster goes off before
you're done...
Casey

In article VCK8c.2068$zc1.453@okepread03, DanG wrote:

Most plaster work is a three step process.

Yes, I originally planned three coats, but it looks like the existing
plaster is two coats. Or would the brown coats and scratch coats be
indistinguishable now? Also, I had heard that two coats was usual on
wood lath.

The existing wall is 3/4", and the wood lath is 3/8" of that. So if I
leave an 1/8" for the finish coat, then the basecoat(s) must be 1/4"
plus the keys. Is this too thick for one coat?

It would probably be more normal to allow the base coat to dry
overnight.

Well, the spec sheet for the Diamond brand finish plaster says that if
it is applied over a plaster basecoat, to apply the finish coat while
the basecoat is set but not dry. I called USG and they thought the
drying time for the Structo-Lite in my conditions would be on the
order of 4 hours.

Thanks for all your help. Your suggestion of a test run is great.

Cheers, Wayne