Replies

1. 
   Gimby | Nov 17, 2006 01:24am | #1

   PVA = polyvinyl acetate. It is like a glue so it sticks really well to surfaces like drywall and evenly sticks and absorbs to both the paper and the mud. This avoids having a different sheen on the mud vs the paper when the paint is applied over top. Do non-PVC primers cover evenly also? I don't know. Anyone?

2. 
   JohnSprung | Nov 17, 2006 01:24am | #2

   PVA isn't a paint product.  It's a bonding agent for cementitious stuff, like concrete, stucco, thinset, etc. It's basically a water based glue that you brush onto old concrete to make new concrete stick to it.  Before PVA, we used to use diluted ordinary aliphatic woodworking glue for that. 

    

    

   -- J.S.

    

1. 
   Gimby | Nov 17, 2006 01:27am | #3

   But it can be a component of a paint product though.

3. 
   BillHartmann | Nov 17, 2006 02:23am | #4

   The first question is what is a primer?

   A primer is a coating used under another "coating" that because it has properties that the top coating lacks.

   Primers are used in applications other than painting. Used in a number of ahesive applications. One of the most common is on gluing PVC pipe.

   In the case of painting the top coat is forumulated for long wear and looks. In general, lots of other differences in the details depending on the application of the paint.

   Paint primers are formulated to stick well, to block stains, and whatever is need to help the top coat hold and look good.

   In the case of a PVA primer it's main purpose is for priming new DW. It seals the surface so that the difference in porasity (sp?) of the paper and DW compound does not telegraph through the finish coat.