Mist coat - chalky finish

18 Apr 2013
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United Kingdom
I used Leyland Contract Matt to mist coat 1 room (many more rooms to do).

The instructions say 9 parts paint 1 part water. Infact I did 8 parts paint 2 parts water as I was cocnerned 9 to 1 was too thick.

The paint is dry and is a chalky finish - t when I touch it I get residue on my fingers and concern is that any further paint will not stick.

I phoned Leyland and got 2 conflicting answers

1 - the stuff is meant to be chalky but if you want to paint over it with vinyl matt you need to wait 2 months for it to dry (????)

2 - vinyl paint over it is fine but acrylic is not without further prep

I then went to the Crown trade centre where they said that I should not get a chalky finish.

For the moment I have bought a tub of Crown paint which says to water down 6 parts paint 4 parts water - I will try that out this week.

I am hoping a more watery paint will lead to less chalkiness.

I mist coated once years ago using normal emulsion and i had no chalkiness so I am wondering whether I should have just avoided contract matt.

My question - is the chalky paint going to be a problem? The room that I did is the bathroom and I was intending to use durable paint which I believe is acryllic - the guy at Leyland said that if using acyrllic then I would need a primer over the chalky stuff.

Crown shop suggested lightly sanding down the chalky paint before overcoating.
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Contract matt is chalky to some extent but shouldn't really be coming off on your fingertips just by touching it - it should need some real pressure or a wet rag to do so. I'm assuming you applied it to bare plaster because your title says 'Mist coat', but you don't actually mention that in your post. If you have applied it to an already existing vinyl, that may explain the excessive chalkiness or it could be a possibility that you have applied the paint too thickly.

You should be able to apply vinyl emulsion or acrylic on top of contract matt without any adhesion issues - in the trade it is the way we do it all the time. The only problem you could have is if the contract paint is faulty. If you feel unsure, wipe the walls down with a dry cloth to remove any chalky residue before using your finish coats. If using a trade paint, diluting with around 5% water is always a good idea to ease application.

I think the reason they have told you to wait two months is because, in some circumstances, contract matt is applied to walls that have been rendered and skimmed before they have fully dried out. This is acceptable procedure because contract matt allows any excess moisture to continue to dry out, whereas vinyl doesn't, but you do need to allow plenty of time for the walls to dry out before applying any vinyl, if this is the case.

Out of interest, what Crown paint do you have that says to dilute it 6:4 with water, as it is unusual for manufacturers to recommend such a high dilution ratio, even though it is often done by many people for mist coating?

The walls are all new plaster (plasterboarded and skimmed - not rendered) - they have had 3-4 weeks to dry and I am happy they are dry as they are all a uniform light pink colour.

I think maybe I did roll it on too thick - will a dmap cloth remvoe all the chalkiness or do I need to sand?

The paint I bought from the Crown centre was one of their brands but with a different name http://www.crowndecoratorcentre.co.uk/product/macpherson-contract-matt/

It does say 60/40 - and the staff said the decorators they talk to do will even do 40/60 or 50/50.
I should add I am aware of all the different opinions onlien of whether to do 20% 30 40 50 or even 60% mix for the mist coat.

Also about whether to do 1 or 2 coats.

I will aim to do 1 coat at 60/40 or maybe 50/50.
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Skimmed plasterboard is usually fine to paint after a week, or sometimes less, so I think you are fine there.

Personally, I would just use a roughish dry cloth to remove as much as possible and then apply your next coat, or a light sand would also be fine providing you still wipe off all the dust. I wouldn't use a wet cloth because you may end up with a patchy surface.

I haven't used Macpherson's paints for a fair few years (they were always decent enough products when I did but that may have changed now) but I wouldn't dilute more than 25-30% at most, although if they recommend more, it shouldn't cause a problem.
I ptu some Macphersons on last night at 50/50 - inital view is that although it is chalky it is not anywhere near as bad- I would say it is more 'dusty'.

Could be down to the fact that it is watered down more - or the fact that I put the Leyland on too thick - overall I am more content that I will be able to paint over the Macpherson products without major problems.

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