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Hey tightcoat


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07-16-03, 01:57 PM   #1  
Hey tightcoat

I just did a job where I was repairing plaster in a living room. This plaster was unlike any I have seen. The scratch coat was about an inch thick and was grey in color. The top coat was 1/4" thick and tannish in color. What happened was the topcoat completely fell off in some spots. I'm talking a 4'x6' area. The scratch coat, however, was solid as a rock. Usually I see wood lath with about a 3/4" coat of plaster over it. That method usually breaks out to the lath. Anyway just wondering.

 
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07-16-03, 08:04 PM   #2  
Re: Hey tightcoat

Interesting. The coat of plaster before the finish coat is called the brown coat. In two coat work it might be put on in a scratch and double operation but is still called the brown coat. How old is the house? Is the plaster over wood lath?
A quarter inch seems a little heavy for the finish coat. If it was not laid on tightly it might not have bonded well. Has the house ever sat through a season unheated? There are some other reasons the bond might have failed. The brown could have been to slick, the brown might not have been set before it dried out. The brown could have set and been retempered. The coefficient of expansion in the whitecoat finish is different from the brown coat. This is not usually a problem except if it went through a winter without heat. The plaster could have gotten wet then dried out. If it is not wood lath that could happen and not loosen the whole job. If the plaster was done in the winter it could have been with oil heat and there could have been just enough soot to hinder the bond.
As far as the color: It was not uncommon in the days when things were plastered to color the finish. Eventually it still got painted but for a while at least it saved a paint job. When my dad plastered the house my folks still live in he colored the plaster. That was in 1962 I think. The last room painted was probably painted about fifteen years ago. This had the additional advantage that a shallow scratch or ding on the wall didn't show up as badly because the color was throughout. Realize of course that the finish is not very thick.
I don't think you ever get to the point that you have seen it all in this industry.
Have you always been in the KC area? I spent 26 years in Hays, Kansas.

 
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07-17-03, 01:14 PM   #3  
I think somebody tried to fix some problems with the plaster some time thats why the top coat was so thick. Anyway, I just finish touching up. Put Venetian plaster on walls and ceiling. Looks awsome. I've lived in KC for 7 years now. Grew up in CT and then CO.

 
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