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Jacqueline
Plaster Wall - Top layer is lifting/peeling

Hi. I'm new to this so I need some help. My home was built in 1924. We have several areas where there are cracks in the walls. I have figured out how to address those, but there are 2 areas where the top layer of the plaster is lifting.  Based on my research, I believe it is skim & paint.  Does anyone have any idea how I should handle this.  The internet is full of advice, but I wanted to get an answer here. Thanks!

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HandyAndyInMtAiry
Re: Plaster Wall - Top layer is lifting/peeling

Jacqueline,

From your picture, it looks as if someone skimmed over a concrete wall. That does not look like a plaster base. But you can still skim over it. If you have never dealt plaster before, I suggest hiring a professional. You can cover the wall with sheetrock, but if you want to keep your home looking, sounding, smelling and working like the original, keep the plaster. It has a much higher Resistance value than sheetrock.

If you want to try to skim coat the wall, remove all the loose plaster, if there are cracks, fill them a lime plaster mix. You never want to use anything that is pre-mixed. Make sure that you have the correct, high quality tools for the job. I suggest that you use a quick set joint compound, maybe a 45 or a 90 minute set. Joint compund does not have sand in it, this is what you want for a skim coat.

I suggest that you drill a few 3/8" to 1/2" holes in various places on the wall. This will allow the skim coat something to bind with, just like the original lathe boards. The skim coat is usually two to three very smooth coats of plaster. You can also mix a little horse hair into the first coat to give it strength. But do not use horse hair on the top couple of coats.

Mix your joint compound according to the instructions on the bag. Follow the instructions exactly. From there, you have a limited amount of time to work. Mix only enough compound to cover the area in question about three times. You are going to add multiple very, very thin layers to the existing wall. A layer coat of about 1/32" to 1/16" is good. Some folks allow the compound to dry and then sand in between coats, I do not. I want a perfectly glass smooth top coat. The top will not be perfectly straight, and it is not supposed to be. You will see small highs and lows in the wall, this is ok. You can spean a lifetime working them down and up to try and get a straight edge perfect coat. By not allowing the compound to dry completely between coats, I have more control over the finish. Each coat will get more thin and smoother. The top coat should be like glass. Now is it time for the first coat. Mix the compound on a table top, and add it to your hawk. Start at the bottom and work your way up in a curve. It depends on your dominate hand as to what way your curve. You want to apply a very, very thin coat, make it smooth, but don't worry about the small imperfections. They will be covered by the next coat.

There are no step-by-step instructions, this takes experience and a lot of practice. It all depends on what you see, feel and smell as what you do or don't do next. I am not trying to talk you out of doing this, but I have been working with plaster since I was a small child, and I am still learning.

Andrew

Handy Andy In Mt Airy NC

Clarence
Re: Plaster Wall - Top layer is lifting/peeling

Andy you said do not use a premix? yet the Joint compound is a premix? The reason for the seperation of the finish coating is mostlikely cauesd by moisture.

For a lasting repair use a lime based plaster mix. if blending it from scratch use 6 parts Lime , 3 parts guaging plaster & 1 part moulding plaster. If you want a very good preblended restoration plastrer look at this product Master of Plaster it is the very best plaster restoration available. Next in line would be USG Diamond plaster not very user friendly but a very good product. Any dry wall compound over a gypsum product will fail depending on the moisture it would last some ware between 5 & 15 years.

HandyAndyInMtAiry
Re: Plaster Wall - Top layer is lifting/peeling

Clarence,

I found some joint compound that is powder in a bag. I define "pre-mix" as already mixed in a bucket. Sorry if I messed that up. I always try to use lime based plaster mix. I am going to look into the two that you recommend.

Thank You for the suggestions

Andrew

Handy Andy In Mt Airy NC

Clarence
Re: Plaster Wall - Top layer is lifting/peeling

Andy look at the Master of Plaster web site I did the restoration on the Blue & White Church interior using the M.O.P. product also Dock Street Theatre  & City Hall those are just some of the 65 in total projects i completed with M.O.P.

I have worked in the plaster trade & this producy is the VERY best i have ever used.

HandyAndyInMtAiry
Re: Plaster Wall - Top layer is lifting/peeling

Thank You Clarence

I will certainly give it a try.

Andrew

Handy Andy In Mt Airy NC

Clarence
Re: Plaster Wall - Top layer is lifting/peeling

There is a plasterer in Willington, NC that i got lined up with M.O.P. about 5 years ago he maybe a distribitor now i can find out if you would like. There is a distribitor in Charleston, SC   called PML Ph# 843-744-1516 tell him Hank gave you this info.

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