We have stripped the wallpaper off the walls in our house - these are what we call gibralter board, what the Americans call drywall or sheetrock, I don't know what it's called in the UK. Now we will hire someone to skim them with plaster (to be finally painted). The spatula used in removing the paper has left some gouges, with occasional little flaps of drywall paper sticking up.
One of the tradesmen who has given us a quote says that the walls must be sanded first to smooth off the protrusions, then painted with an oil-based sealer before the skimming. Another says sanding is not necessary, he proposes to paint with sealer then start applying the plaster. In both cases the plaster will be applied in two or three layers.
We are concerned about this inconsistency. Is it necessary to sand first? I would have thought the little bits of paper sticking out would either require extra thickness of plaster to cover them, or would tend to come through to the surface and maybe create irregularities, perhaps responding differently to paint. How thick would the total plaster layer be normally?
Thanks in advance for advice.