Skimming question

[Graham Jones]

When skimming undercoat plaster how many coats of finishing plaster do I need to apply? I guess I need about a 3mm depth but never having skimmed before I don't know whether this depth can be applied in one go.

Can it?

Thanks,

Graham

[Andrew Gabriel]

Normally two coats. The first goes on as thin at you can and the surface will be level with the most prominent points on the scratch (under) coat. This means it can't be polished off, but it's flat for the second coat. Then you do a second coat on top which will thus always have some plaster thickness over the most prominent points on the scratch coat, and can be polished off.

I have on occasion got away with just one coat, but I start with the intention of doing two. If the first coat seems like it will polish up without hitting any of the prominent points on the scratch coat, then there's no need to do a second coat. IME, this is less successful if reskimming as you need the thickness of two coats to help with the strength -- it doesn't bond as well to the old finish coat as it does to a new scratch coat.

[Graham Jones]

Thanks Andrew