I've just replastered the bedroom with a 2 coat skim plaster.
I wasn't able to do the whole wall in one go as the pros do it and had to break it up into manageable sections.
Now I've applied the 1st mist coat, and used Easi Fill to patch up the iffy areas of the skim coat and sanded it with 100 grit sandpaper.
I've done this process twice since after the 2nd mist coat (slightly less water) it still had a few uneven bits.
now i've applied the 3rd mist coat with about 10% water to crown PBW emulsion, i'm still getting areas where the paint is not covering the plaster. (I can see dark plaster patches as opposed to white)
I suspect the patches are due to 1) over troweling (too polished) 2) bits of pva/water solution on the plaster joins. I tried sanding these areas down and scraping off any pva/water drips I could see after the 1st mist and 2nd mist coats.
Any advice to over come these areas?
Would an oil based under coat help and then apply another coat of normal white emulsion before putting the final colour emulsion?
" suspect the patches are due to 1) over troweling (too polished) 2) bits of pva/water solution on the plaster joins." - you are correct, not uncommon and not usually a problem, providing that the mist coat is actually adhering well.
different areas of plaster will take the mist coat differently and will look patchy. pva should not be on the surface of the plaster - underneath as a sealer yes, but not on top. i often add a tiny bit of pva to the mist coat diluent to help adhesion but never pva or pva solution on it's own.
you should find these areas cover with full strength emulsion. you are not helping yourself by using crown emulsion - absolute c@*p in most professionals' opinion (certainly in mine! diy-ers seem to love it. why? beyond me). get yourself some decent paint such as dulux trade emulsion or leyland. give it a couple of undiluted top coats of quality paint and it should cover.
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