Water marks in finished plaster?

by Colin
(UK England)

Hello, I have been getting more confident getting plaster on the walls in my kitchen. The results are nice and flat but a bit variable in that sometimes there are brownish marks in/on the surface rather than a nice even pinky plaster finish. I hope you can help me to get a better result.

I'm using fresh new bags of Bonding coat and Multifinish plaster, clean tools, buckets and water. Mixing the plaster thoroughly with a paddle and electric drill but not fast and for about 1.5 mins max.

The walls are Brick and started out nice and clean, but I applied one coat of PVA/water mix as a bit of insurance to seal up the wall.

Seems like I get these marks more if I work longer getting the plaster flat, I would like to understand where these marks come from.

It's not a big problem because the plaster will be covered with wallpaper or paint, but I should like to achieve a first class job.

I'm in a hard water area.

If you can give me some advice and guidance that would be much appreciated.

Regards

Colin.

Answer

Hi Colin

Try using as little water as possible. If the wall is really dry then water is needed to liven it up - but if you control the suction (as it sounds as if you did with the pva) then it is possible to complete all stages with no water. Firm pressure on your trowel will give a nice even finish - but the trick is to control the suction first.

Paul