We have a 1900 colonial 2-story with horsehair plaster throughout the entire house. The vast majority of the house is wallpapered and the paper is in rough shape. We'd like to paint the walls instead of replacing the wallpaper.

I took the paper down in one room and there is only the brown coat of horsehair....this appears to be the theme throughout the house. My understanding is that back in the day they didn't bother putting a finish coat of plaster on if paper was to go up.

The brown coat is in relatively good shape with few cracks or gouges. The problem is that the surface is gritty if you run your hand against it. I plan to patch the cracks just like I would patch drywall cracks, but I have a feeling the brown coat plaster will just suck the water out of the compound...leaving the repair brittle. I will need to seal the entire surface first before doing any repairs.

Here is my plan:
1. I've used Zinnser's Gardz sealer before on new drywall...I liked it. I'm thinking a number of coats on the brown coat will seal the surface and also reduce its grittyness.
2. Repair the cracks using mesh tape and compound.
3. Skim coat the sealed and repaired surface using a Durabond setting type compound.
4. Sand, prime, paint.

Does that sound about right? I know I won't be applying a true skim coat, more or less just smoothing the surface out with a very thin coat of compound. I'd use a plastic 12inch "Magic Trowel" type knife to apply the super thin coat.

What do you think? Recipe for success or am I planning for a disaster. Thanks in advance!!!

 

Sounds about right except I'd only use one coat of Gardz, the skim coat of joint compound is what's going to smooth the wall. Also, use paper tape on the cracks, it's actually stronger than the mesh stuff. If you insist on using mesh, use a setting compound instead of joint compound.

 

Thanks Mitch! I was thinking that two (or more) coats of Gardz is needed because the brown coat is so porous that it will take more than one coat to adequately seal it. I'm not expecting the Gardz to do any smoothing.

I'll use the paper tape too...I've already got plenty of both.

Now I have a question on skim coating. As a non-professional diy'er I'm looking to make my life as easy as possible. I saw something at Sherwin Williams that caught my eye.

There was a picture diagram on how to use their "Magic Trowel", which is basically a 12" drywall knife with a removable tear-drop shaped plastic edge. It makes the knife a cross between a squeegee and a knife.

Anyway...the diagram said to thin the compound out enough so that it would stick to a roller. Then just roll the compound mixture onto the walls, and then use the "Magic Trowel" to take off the excess. Then the low spots are filled in and you are left with a smooth surface.

Too good to be true?

 

#1 - like Mitch said, 1 coat of Gardz is sufficient
#2 - paper tape is best! For minor cracks you can just scratch them out a little and fill with durabond.
#3 - regular joint compound would be easier to skim coat with and sands easier - but either will work.
#4 - sounds good, don't forget to wipe off the sanding dust before applying the primer.
#5 - relax and admire your handiwork

 

Never heard of the Magic Trowel, let alone used it.

Mudding is not that bad a job, get a couple different knives (including a 12") and go to work. Are you going to screw up? Of course, but it's not the end of the world. Large ridges and bumps can usually be knocked off with the knife and the surface can be sanded and worked with a wet sponge as well. Screw up an electrical job and you could burn the house down; there's just no such risk with this job.

 

I missed post #3

While I'm not familiar with "magic trowel" that concept has been used for years. It works best if there are 2-3 workers, 1 rolling on the mud and 1 or 2 smoothing it out with a wide knife.

As long as you don't dry roll the Gardz - one coat is fine.

 

Thanks again guys! Definitely seems easier now. One last question. After I skim coat and get the surface nice and smooth....what should I use to prime the skim coat with before paint?

More Gardz?
Plain old PVA Primer?
Oil Based?

Thanks!

 

PVA unless you plan to use oil based paint (which I would doubt), in which case you would want an oil based primer.

I only use Gardz to seal exposed gypsum on damaged drywall, I don't use it under paint.

 

Most any latex wall primer will do. The better primers will hold the gloss better if an enamel is used for the top coat. Latex primer over new drywall is fine even if oil enamel is the top coat.