Skimming over satin finish paints and render.

[DIYDouglas1]

I want to reskim a wall in my bathroom which is painted in the satin-finish paint. I'm wondering if I can get away without pva'ing the wall before skimming, as the satin paint seems to have some waterproofing properties, thereby preventing absorption of water/drying out of the skim. I've pva'd satin walls before skimming in the past, 'just in case', but as it takes ages to absorb/dry, I'm wondering if its worth it.

Also, I'm about to skim over internal render. Do I need to pva this before skimming?

Any help would be much appeciated.

 

[Richard C]

If you don’t key a satin or gloss finish by scoring the surface before plastering the bond will be very weak & the plaster very likely to come off with the slightest knock! To key this sort of finish, I use either a (very!) stiff wire brush or the corner of an old scraper, sometimes both, to give a criss-cross pattern of scratches over the whole area; they need to be deep enough to penetrate through the paint surface to provide a decent key. I then go over the whole wall with a liberal coat of 5-1 water/PVA mix & leave it to dry thoroughly, at least over night. Prior to skimming, I apply a stronger that normal 2-1 water/PVA mix & skim when tacky.

Apply a liberal coat of 3-1 water/PVA mix over the render; when dry, apply a second 3-1 coat & skim as soon as it goes tacky.

 

[DIYDouglas1]

Many thanks. Very helpful.