Hi Paul
My plastering is slow and I think that I fuss too much with the coats,
although I am trying to learn to ignore the marks/lines/dips as much as possible and then go back to them. After the second coat dry's, it is blotchy and not an even tone over the whole area, is this normal or is it something to do with the mix?
The bits of plastering I have done always have this characteristic,
although they have been flat and smooth and once painted its obviously
not noticeable, so should I be concerned? It's just that when I have
seen plastering by a professional, it dry's to a uniform colour.
Regards
Ed
Answer
If it is okay when it's painted then that is all that matters.
Why this may be happening
This uneven plaster colour tone is happening due to the 2nd coat being too thin and the the 1st coat being visible in some areas of the finished surface.
This can be due to applying the 2nd coat too thinly or scraping it off when you are trowelling the wall in stages 3-6.
How too resolve
The 2nd Coat
When applying the 2nd coat - having your trowel slightly flatter so that the leading edges is closer to he wall will lay it on a bit thicker.
Trowelling
It may be that you are applying the plaster to the correct thickness - only to scrape it off when you are trowelling. If in the trowelling stages (3-6) you are collecting plaster on your trowel then you have the wrong angle and you are scraping the 2nd coat off. When the angle of your trowel is correct (the leading edge approximately 15mm away from the wall) the trowel will act to just push the plaster around - from the highs to the lows and provide a nice uniform flat finish.
So either way it sounds like a trowel angle issue. When the trowel is flatter to the wall, firm even pressure is required, so your arm may become more tired - but it will soon get use to it!