Replies

1. 
   BillBrennen | Nov 24, 2007 06:35am | #1

   Rez,

   The bonding agents for paint, to help it stick to crumbly plaster, are thin consolidants that penetrate into the plaster to help it hold together when you apply paint. Original Kilz is more designed to stay on the surface of the wall and provide a smooth white base for paint.

   Kilz original is fast-drying oil based. It is NOT shellac-based. B I N primer is pigmented shellac.

   Bill

1. 
   rez | Nov 24, 2007 08:29am | #3

   Seems more jobs have been coming dealing with old plaster fixes of late and desire to present the best for the involvement is why the query.

   So if after placement of a plaster washers to secure a lose area it would be prudent to cover the wall with a bonding agent before applying a stain blocker like BIN or Kilz then followed by a textured surface?

   Thanks again. 

1. 
   BillBrennen | Nov 24, 2007 09:41am | #4

   Rez,You only need the plaster consolidant if the surface is powdery/unstable when disturbed. Lots of times plaster will fail at the lath or the browncoat boundary, but the surface is still sound. If plaster washers will fix it, you want to patch over the washers before texturing and priming.In other words, there are different kinds of "loose" with old plaster. If you have both kinds of failure together, it is simpler to go back to the lath and replaster, or to the studs and do a new wall finish from the framing out.Hope this helps, and is clear.Bill

2. 
   Lansdown | Nov 24, 2007 06:58am | #2

   http://www.larsenproducts.com/plasterweld.htm

3. 
   Jer | Nov 24, 2007 03:07pm | #5

   Are you talking the old white coat or the crumbly brown coat just beneath? You should not use certain bonding agents like Plasterweld directly on the crumbly brown coat. It's best to use a penetrating product on the loose stuff first, then use the bonding agents. As Bill said there are different degrees and types of loose plaster.

   Just make sure all the old loose stuff is dug back to the point that it is still in tact, make sure all holes are under cut around the sides, then clean it out with a vacuum and proceed.

   Often I will not use any bonder at all but rather soak the cleaned out area with water using a spray bottle, let it soak into the wood lath and old plaster, spritz it lightly once again and then go to town with your fresh plaster. It's best if the fresh plaster is a little looser mix.

   If you're talking about skimming over an old white coat, you need to scarify the surface first with rough grit paper like 36 if you can get it.