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Plaster Washers

Posted by flyingtim01 (My Page) on
Mon, Nov 26, 12 at 16:02

Hey Guys,

I've started working on our front hall/staircase in our 1910 'colonial'. I removed the outer layer of wall paper to find a layer underneath that (painted, of course) and a third layer under that on top of the plaster. I spent all day yesterday removing the paper and glue, and am left with a wall that resembles the surface of the moon.

I pulled loose plaster chunks out, however there are some areas that are soft where the plaster has lost it's key. It's been recommended to me to just go over it all with 1/4" sheetrock, ironically because it would somehow be easier to wrestle a dozen sheets of sheetrock into a stairwell. I don't want to do that, I think it would be easier, cheaper and quicker (and much more in keeping with the whole old house thing) to repair the plaster.

I've seen referenced here and some other places on the web that I should be looking into plaster washers to re-secure the soft spots to the lathe before I start patching the cracks and gaps with Easysand. My question is, is there a particular technique to using them? I know I'll have to pre-drill into the plaster, but other than that... Is there a speficic design? Spacing? Etc. Just looking for a little guidance before I start drilling holes and making a mess of my front stairs!


Follow-Up Postings:

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RE: Plaster Washers

No need to pre drill, in fact, do not.
Here is a vid that shows how

Here is a link that might be useful: plaster repair


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RE: Plaster Washers

Unless very large areas of plaster have detatched completely, it would be highly unusual to need washers on a wall - their main use is for ceilings where the considerable weight of the plaster and gravity are causing the ceiling to fail.

There is a technique for walls in which a number of holes are drilled and glue is injected and the wall is braced until the glue dries. There are instructions for this online, I believe. In most cases, however, fiberglass mesh - and the new thinner version is especially good for this use - is installed either over the entire wall surface or selected problem areas then coated with joint compound. That's all that is needed.


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RE: Plaster Washers

"their main use is for ceilings where the considerable weight of the plaster and gravity are causing the ceiling to fail. "

Or anywhere the plaster keys have failed.

They DO NOT pull the plaster back to the lath though.

It needs to be forced back against the wood lath BEFORE driving the washers and screws (and catching a few studs helps a lot).

It also takes a decent amount of finish material to cover the washers.

All the mesh on the surface will not really help if the keys have failed.

Given what else may be in the walls, the glue method still sounds like a bad idea.


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RE: Plaster Washers

We have used the washers (Kilian Hardware is where we get them, and lots of other cool stuff). They are easy to use, but they DO require a few coats of plaster to cover them. We prefer them on ceilings because ceilings are so difficult to work.

For a wall you could use the washers. But for me, I'd break out the loose plaster and reapply base-coat plaster in a few coats. It will key to your lath really nice, and eventually you'll bring it level to the existing layer.

This will also give you some practice with plaster. Because no one really plasters any more, when plaster is mentioned everyone freaks out like you need a degree in rocket science and the touch of Picasso to do it.

Hardly. Once you get the unkeyed areas filled in, then prime appropriately (sometimes very old plaster is tough for the new plaster to adhere to) and apply a skim coat of finish plaster. The worst thing that could happen is you'll have to sand down some high spots and skim it again.

I don't recommend the drywall at all. You received this recommendation from someone who has never used plaster.


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RE: Plaster Washers

Thanks for the responses.

Clarion, I've actually been leaning towards just digging out the loose plaster and trying my hand at plastering. I figure if I'm going to be needing multiple coats to cover plaster washers, or at least a skim coat to cover up what's left of the adhesive technique, I might as well just pull the loose stuff out and start from scratch. And as you pointed out, I'd get some practice working the plaster, which will be a highly applicable skill in this house...


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RE: Plaster Washers

Durabond setting compound is as hard as old plaster.

Make sure you get a god finish it does NOT sad easily.

Easysand is another setting compound (these compounds like old plaster harden by chemical reaction, not just 'drying out').

old plaster can pll so much water outof setting compound it doesn not harden correctly when incontact withthe old plaster.

Eucoweld bonding agent, or Elmer's white glue diluted 50% with water both work well.

Wait till either has become tacky and started to set before applying new material.

the old plaster finish coat is not just plaster, but plaster mixed with lime putty.

Lime putty alone takes weeks to months to harden fully, straight plaster hardens so fast without a lot of retarder that weakens it cannot be worked well.

The mixture takes a few hours to overnight.

Unless the job requires historical plaster repairs I use setting compound.


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RE: Plaster Washers

In addition to the adhesive to bond the new plaster to old, you should spray the area with water so that it is damp--that will make the water sucking less from the new work.


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RE: Plaster Washers

flyingtim01: Good for you in your determination to learn plastering. I would suggest, however, beginning in a fairly inconspicuous place. IMHO, plastering is one, or perhaps even #1, of the most highly skilled of all the building trades. I once had the opportunity to watch a plaster restoration in a historic building. They made it look so easy, even in the repair of 200+ year old plaster moldings. The truth is that there is just no substitute for "time on the tool" - often years - for developing into a skilled plasterer.


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RE: Plaster Washers

Find a copy of Plastering Skills by F. Van Den Branden and Thomas L. Hartsell.

Amazon has it sometimes.


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RE: Plaster Washers

what brick said about using a bonding agent: I would not work without it. Prevents headaches down the road, and cheap insurance that job comes out well. Plus it stops the crispy crumblies. The one thing is, when you apply it, the alkali of the plaster creates huge surface tension effects. So I brush it on, wait a minute (actually I go on to another area and then return), and overbrush again. You get much better penetration of the liquid that way.

I use durabond for my first fill, easysand for subsequent layers. Easysand makes a nice finish layer but for patch strength I'd rather use durabond. I don't know what they sell premixed joint compound for other than convenience, but I would never use it with old plaster walls--all I ever got were frustration and crappy results. Durabond and easysand work much better with old plaster.


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RE: Plaster Washers

It is true that plastering is quite a skill to master. Plaster from scratch, that is. It's one thing to repair a wall that is basically true (easy), which is your situation.

It's quite another to take a wall down to lath and replaster it and have it come out true, flat, and smooth. Quite a few orders of magnitude in difference.

We all do a lot of the first, rarely do we attempt the 2nd.


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RE: Plaster Washers

Thanks for all the input, all. I guess I'm going to be trying my hand at plastering from scratch, basically. a small wall next to the front door was basically all loose plaster, save for about 3 inches in the corner, and about 2 inches right next to the front door. It had been patched previously, and the patches themselves are rock solid, if ugly.

What could it hurt to try, right? If it turns out horrendous, I'll just cover that small wall with 1/4" sheetrock. The rest of the front hall seems to be in need of just small patches, which I'll do.

I bought a bag of Structolite and plan to use that as the base coat. Of course, the depot didn't seem to have anything appropriate to spread this volume of basecoat and press it into the lath...can anyone recommend a good place to find some half decent plastering tools?


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RE: Plaster Washers

You may need some retarder to slow setting for your first try.

Find a wall finishing supply house.

The big box stores rarely seem to have everything needed for plaster work.


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RE: Plaster Washers

You are exactly right: You've got nothing to lose by trying, and plaster is relatively cheap.

Big Box: Another reason folks abandoned plaster was because they couldn't by it. The greatest tool old house lovers have ever received was the Internet. Now you can order whatever you want.


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RE: Plaster Washers

Time to learn what a Darby is and how to use it.


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RE: Plaster Washers

i just so happen to be redoing a stairwell in a similar age house that also had several layers of wallpaper. i sort of have taken a combined approach. in some places, where the plaster had been partially chunked out and repaired with a foam filling material (no joke) i used my dremel with a diamond bit (critical) and cut large squares out down to the lathe revealing two studs. i then cut a piece of 1/2" drywall to fit the section.

the stairway is in half-floor sections with landing. the portion i'm dealing with has stairs above it. i had two major plaster cracks in the 'ceiling' section (under the stairs above). one of these i secured with plaster washers to great effect...but yes, expect at least 3 coats of compound to smooth it. now one other section i attempted with plaster washers but just couldn't get what i wanted. there i did glue and screw drywall overtop.

overall i'm pretty pleased with how things are going. "gluing and screwing" drywall is without a doubt less work, but plaster is such a great material i like to keep it when i can.


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