Preparing plaster for another coat

[TD]

Regular readers may not remember that I took away skirting panels in my dressing room, and I am attempting to finish it off by covering the exposed concrete with plaster. All in order to get another few cm to fit the desired wardrobes.

My first attempt was okay-ish, but I needed to sand it down where it was too thick, and put another layer of plaster on to fill in the uneven bits (it was my first experience with plaster!).

I sanded it down reasonably well, and then realised that I could have evened it out much quicker using the flat edge of the spatula, nearly parallel with the wall. So I finished it off like this. It seems fine but very smooth compared to my 75-grit sandpaper.

My question is - before I go for my second coat of plaster, do I have to do anything to the first coat to provide a key?

[harryagain]

Best to go for it when the first coat is hard but still damp. Wet down with water and a brush, don't put layers on too thick. Or use Polyfilla or similar for final coat, much easier to use.

[TD]

Too late for that, first coat is days old. I will give it a spray with water before doing the second.

Why exactly is Polyfilla easier to use? I have some similar filler that I could use, but my non-professional pride(!) is telling me to try and finish it off with plaster.

If anyone wants to talk about the differences between plaster and filler generally, I'm all ears. To me they look and feel quite similar (dons flame-proof hat).

[Andrew Gabriel]

Actually, before it's completely hard if you can.

Mix a little PVA in with the water (you have to add water to PVA in small amounts to start with, or it won't mix easily).

It sets differently (I think the setting is more resin based), and it sticks to many materials, which finish coat plaster isn't very good at, except PVA or another layer of plaster which isn't quite set yet. You can mix a little PVA into plaster to make a filler, and that's also what bonding coat plaster is (but bonding coat is too course to make a good finishing layer, although I have done it a few times when that's all I had, but takes more effort to polish it up).

Plaster works well over large areas, but is pretty useless for small hole filling. Polyfilla is the other way around (and would be very expensive to do large areas).