Using water based undercoat

ennogs · 26 Apr 2012 at 16:59

I am about to paint the doors and skirting boards in my flat. First I am applying a water based undercoat.

Do I first need to sand the old paint a little bit before I apply the undercoat? I just mean to ruff it up a little bit not sand it right down.

peterattheboro · 26 Apr 2012 at 17:02

Undercoat should be applied to bare wood as it sinks in. If there's already paint on it then it won't do it's job.

Can't you just paint straight over it with gloss?

haaammit · 26 Apr 2012 at 17:06

Actually primer goes on the bare wood.

Gloss doesn't stick well to gloss, so it's better practice to undercoat then gloss.

op - yes - you should key the old paint first - use a light grade paper (120-180 grit) and hope that the old paint wasn't one of those awful one coat types as it will just shred up in little strips.

ennogs · 26 Apr 2012 at 17:21

Quink said:
Actually primer goes on the bare wood.

Gloss doesn't stick well to gloss, so it's better practice to undercoat then gloss.

op - yes - you should key the old paint first - use a light grade paper (120-180 grit) and hope that the old paint wasn't one of those awful one coat types as it will just shred up in little strips.

Luckily it is not doing that.