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Matt Emulsion Cracking and Crazing

 

Matt emulsion cracking and crazing can be a big problem, and it’s one that comes up regularly on the Decorators Forum UK. In this article I’m going to talk about the main cause, what you can do to prevent the issue and what you can do to fix the problem if it has already happened.

 

The Cause

 

Normally this happens when you’re painting with vinyl or contract matt emulsion over the top of a shinier paint, usually silk, however it can also happen when you are painting over other products. The shiny emulsion is very flexible and as you paint over it, it absorbs some of the moisture out of your newly applied paint and expands. The matt paint you are using is not very flexible and dries first. As your silk dries again, it contracts and pulls the surface of your matt, which causes cracking and crazing.

 

Which Emulsions are more susceptible to Cracking and Crazing?

 

Normally, the only paints which will craze are contract, or vinyl matt emulsions. Retail matt emulsion is very much like a contract matt, which can be particularly bad. This is because these paints do not have much in the way of polymer binder in their formula, and so aren’t very flexible.

Durable matt emulsion (kitchen and bathroom paint) doesn’t normally craze so you are safe when using products of this nature. Or the alternative is to use an eggshell or mid-sheen. The only downside of this is you will not achieve a true matt finish.

 

Prevention

 

All you need is a barrier coat between your shiny old paint and the newer matt emulsion. Something that is flexible enough to withstand the tension and waterproof, so no moisture is allowed to pass through. A product called soft sheen is perfect, but you can also use eggshell emulsion or Zinsser Gaudz. Just don’t rush it, apply your barrier coat then give your wall plenty of time to dry before applying matt.

Another tip is to not sand your shiny wall before you repaint it. If you abrade the surface it is more likely to expand and cause problems.

 

The Cure

 

If the issue has already happened and you’re left with an horrendous looking mess, don’t panic!! There is a wonder product that will sort you right out. Zinsser Peel stop is designed for this type of problem!! You can get it from any Crown Decorating Centre, as well as some other outlets. Make sure you phone ahead to check stock as some stores will need to order it in for you. Online may be an easier way to get your hands on it.

 

Peel Stop does a couple of things. First off it acts as a barrier between your wall which has now cracked and crazed and your new matt paint. It also fills in a lot of those hairline cracks. You may want to give the cracked paint a little sand down, then apply two thick coats of Peel stop. Once you’re done, give it a day to dry out properly, then paint with your matt. If the odd crack does show through, you can always get the Toupret out. Job done

 

Peel Stop is the ideal solution, whether you want to prime your walls before applying matt paint, or you need to fix the issue of crazing.

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What do Other Decorators Think?

 

Peel stop is the only product I use for this. I had to re-dec a full house once which was matt over silk and I learned the hard way how to tackle it. Never sand silk down before you paint over it. As long as you remember not to sand you don’t normally have any issues, but if you do then just bang 1 thick coat of Zinsser Peel Stop over any crazed surface and it fills almost every crack.

Mike Gregory

Gardz …. Every time, that stuff is like liquid gold as far as I’m concerned

Andy Stammers - Matt Emulsion Cracking and Crazing

 Paint soft sheen on to silk first then matt over the soft sheen. I hate silk!!

Paul Thompson

Happened to me with around 40 kitchens and bathrooms

Dulux reps came to have a look took samples of the paint I was using. They said it was nothing to do with them it cost me around £4000 to put it right. Hence Dulux can f**k right off they lost a £40,000 a year customer 👊

Karl Okey

 Gardz!! I just finished a silk Room, gave it a buzz over with my mirka, applied a coat of gardz then 2 coats of white contract matt. No issues what so ever!!

Louis Wells

The cause of Matt paint cracking over silk is because when the matt goes on it softens the silk which makes it expand, the matt paint dries on the surface first, then the silk underneath dries after, which contracts pulling the matt apart making it craze. If something you have painted has done this then give it a coat of peel stop as it acts as a barrier preventing the silk from softening underneath.
I done an experiment on the last 3 jobs doing matt over silk by rubbing 1 wall down but not rubbing the other walls down until after it has had a coat of Matt. The wall that I rubbed down on each job crazed, the others were fine. Therefore if you are painting matt over silk don’t rub it down first, as it clearly softens the silk more by doing so.

Dean Johnstone

I like to apply a barrier coat of soft sheen over something like silk before I use matt emulsion. This stops the moisture from my matt softening the silk and expanding it. The soft sheen itself is flexible enough to deal with it. If you do this, you won’t need to use something like Peel Stop afterwards to fiz the crazing.

Painter Jim - Matt Emulsion Cracking and Crazing

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Matt Emulsion Cracking and Crazing

DISCLOSURE: Some of the links below are affiliate links, meaning, at no additional cost to you, we will earn a small commission if you click through and make a purchase. You can read more about our affiliate relationships in our T&Cs.