Re-skim old plaster - too thin in places.

jefsboysAugust 12, 2010


I am renovating a house I just bought for my family. It is a wonderful 2.5 story built in 1904.

We are working on the bathroom now and here is where I am....

We stripped the wall paper in the bathroom and found severely chipped and flaking paint. After 20-30 hours of scraping paint to the original plaster I decided to re-skim the walls.

I got Red Top Gauging Plaster. I mixed it up for the sand float finish. After some finishing test in the closet I see that they probably used a wood float originally in the house so that is what I am using.

To the issue... I did my first wall tonight with the skim coat and floated it out with the wood float, now I see that I was thin in a couple of small areas. The Red Top calls to be a 1/16" thick and doubled back over with pressure. I have some smaller areas where I can see the through to the old plaster.

Is this going to cause a problem with plaster falling off or if the texuture is good enough do you think I would be ok with letting this dry and then going through the priming/painting process?

I don't mind doing a second coat on the wall but if it is not necessary then I won't. If a second coat how long would I wait before applying it?...

Thank you in advance,


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If it was mixed properly (Lime putty, sand and gauging) which isn't exactly apparent from your post, you may or may not have problems where it does not meet the recommended thickness. The possibility exists on the thin areas that it will evaporate dry without curing. Water is needed for the lime to cure, and when the water evaporates quickly (more likely in a too-thin application) the plaster reverts to a powder state instead of setting up hard.
You'll know in a day. If you can powder off spots with rubbing, you need to apply it thicker.
If the problems spots are quite small in size, you could wait until after priming, then, treat as a drywall repair, with regular mud.

    Bookmark   August 13, 2010 at 12:10AM
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Excellent. Thank you.
Yes, the mix was done precisely as instructed on the Red Top Gauging Plaster bag (lime putty, then gauging and sand - exact proportions from bag). I put two coats of Tammsweld on the wall before applying skim coat.

Thank you for your input. Any other advice on this is greatly appreciated if there is more.


    Bookmark   August 13, 2010 at 7:18AM
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Sorry for doubling up here...
Let's say after 24 hours I just want to apply another thin layer of skim coat....
What would be the steps at that point?
Would I put another coat of the bonding agent on again and then skim coat?
I have only done a small section in the bathroom as I am hoping to get this technique down before doing the larger areas of the bathroom (none larger than 30 sq. ft of wall area).


    Bookmark   August 13, 2010 at 8:51AM
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Since it's a lime plaster, you have a little time where it will bond perfectly well without benefit of a bonding agent, but the sooner the better IMO. Wet it down first.

    Bookmark   August 13, 2010 at 2:21PM
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