Mist Coat Nightmare

21 May 2024
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United Kingdom
So I’ve moved into a new build at the end of March and just gotten around to trying to paint the plaster walls. I had a viewing in January and the walls had been plastered by then so they’ve had at least a few months to dry out.

Went in with a mist coat as recommended and made sure to dilute it down according to the directions on the tub. (Used Leyland Contract Matt).

As you can see from the photos the internal walls for the cupboard and the ceiling are fine but the other walls look an absolute mess. Is this a case of poor plastering, and will I need to get the contractors back out to sort it? It’s my son’s room and he has a disability so needs his own space, I was just wanting to paint it first so he had somewhere to go and get peace and quiet when he needs it but this has melted my head.

I’ve read it could be something called mapping and you can use a Zinsser primer over it but it’s not cheap and I don’t think I should be having to fork out more money if it’s a case of shoddy work.

Thanks for any help/advice you can offer!


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Bodge a cheap diy sander on vac and 120grade sand.
Block of wood with 120 grade sandpaper and sand to make smooth.
No need to over sand. Contract emulsion is very chalky.
You need to mix paint well and a cheap way is to put a wooden spoon in a cordless drill.
Looks like the water has not mixed with paint so patchy.
Also if you roll too much then the roller becomes solid and hard Vs staying fluffy.
Try loading roller more and rolling walls less so roller stays full of paint and fluffy.
Contract matt paints are normally inferior paints used for plaster that hasn't completely dried out. They have a very low level of latex/acrylic that enables the water in the plaster to evaporate out into the room.

From your images, I cannot see if the plastering is at fault, or your technique. With respect, I think that you may have rolled the paint and then "overly" aggressively, rolled much of it back off.

If , when you run you hand over the surface you can feel pronounced ridges, then yeah, it is down to the plastering, but even poor plastering should, from a distance, look OK

My advice would be to bin the contract paint, but I understand why you wouldn't want to do that. Perhaps try a full fat coat on one wall, then (slowly, and without applying a lot of pressure) apply another wet on wet coat.

How are you rolling the walls? Using a 9" roller on its own can be really hard work- I alway use a roller with a retractable extension pole. The pole enables me to use the whole of my body weight to distribute the forward pressure but without applying too much pressure.

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