Matt Emulsion Cracking and Crazing

Updated Feb 29, 2024 | Posted Aug 27, 2019 | Professional insight, Miscellaneous, Product Advice | 10 comments

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 blog, 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.

 

What is The Cause of Crazing Emulsion?

 

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 such as wallpaper paste. The shiny emulsion is very flexible and as you paint over it, it absorbs some of the moisture from 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 fairly 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.

 

Preventing Cracks When Painting

 

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.

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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.

 

How to Fix Cracked Emulsion

 

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. Ordering online may be an easier way to get your hands on it. Click here to see online prices.

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. It’s an easy fix really. Click here to see Zinsser Peel Stop online.

Matt Emulsion Cracking and Crazing – by Mike Gregory

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.

Mark Robins

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Gardz …. Every time, that stuff is like liquid gold as far as I’m concerned. You only see crazing once in a blue moon, so it isn’t a major problem. It’s handy knowing how to deal with it though.

Andy Stammers - Matt Emulsion Cracking and Crazing

Paint soft sheen on to silk first then matt over the soft sheen. I hate silk!! If your matt emulsion is crazing beacause of wallpaper paste, I often find a coat of Zinsser Gardz is the way forward. To solve crazing, just apply a coat of Zinsser Peel Stop.

Paul Thompson

Happened to me with around 40 kitchens and bathrooms.

Dulux reps came to have a look and took samples of the paint I was using. They said it was nothing to do with them, it cost me around £4,000 to put it right. Hence Dulux can f**k right off they lost a £40,000 a year customer 👊

Karl Okey

Gardz or Peel Stop!! 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’ve 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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Am I the only person who’s had matt emulsion cracking and crazing over cleaning products, or grease? It’s anything that creates a film over the surface you’re painting really. When that film contracts under your paint, it causes crazing. PVA on a surface can cause it too.

You just need to be sensible. Clean all surfaces down before you paint if you think you could have problems. If you do have a problem, just bang a couple of coats of Zinsser Peel Stop on there. Job’s a good ‘un!

Rob James

Don’t worry about preventing matt emulsion cracking and crazing. If it does, just fix it with a thick coat Zinsser Peel Stop. It fills all the cracks, makes a barrier, and prevents any further issues. It’s a quick and simple solution, so no need to panic.

Ross Green

Updated Feb 29, 2024 | Posted Aug 27, 2019 | 10 comments

10 Comments

  1. Tommy

    Bang on, for me these products are a must to have in the van at all times… On my shelf, there is always a tin of B.I.N, gaudz and peelstop. Soon as one is empty i replace that day..

    Reply
  2. Calvin Jones

    I think i might prefer to use a more flexible matt (i.e a durable/scrubbable matt). But a decent primer/sealer would also work. If a customer was set on a particular paint this this approach would seem like the way to go.

    Reply
  3. John

    I have just painted Valspar Matt on top of fresh Crown Matt and the paint has cracked and peeled. The Crown was watered down as I was painting on to new plaster ( the plasterer advised me to water down the paint 70:30). Any ideas please as to why this would have happened? Should I use the peel stop or should I sand back to plaster and start again?
    Any help is greatly appreciated.

    Reply
    • Mike Cupit

      I couldn’t tell you what has caused the issue without seeing the job, but your plasterers advice sounds correct. I would personally give the whole loat a good thich coat of peelstop

      Reply
  4. Sylvia

    I used valspar mixed paint durable mat on top of silk finish. Tiny little porcelain cracks all over. Is this product the only solution. Should my decorator have known this would happen.

    Reply
    • Mike Cupit

      You can’t really blame your decorator because 99 times out of 100 this wouldn’t happen. Personally I’d as your decorator to sand down the emulsion, apply a good coat of peelstop, then another 2 coats of emulsion. I haven’t seen the job, but from what you’re describing, peelstop sounds like the best solution

      Reply
  5. Amy

    I’ve put up a wall doctor white beading effect wallpaper from b&q and emulsioned it this morning with Valspar Trade scrubbable Matt which says it’s a primer and top coat in one. I have just noticed it is starting to peel and crack not everywhere but in various places, so annoying! Do I definitely need to get peel stop or could I sand the cracked bits and use a mid sheen emulsion and leave it as that? Any help would be much appreciated

    Reply
  6. Christina

    I would love some advise please. I had silk paint on both my sons’ room. I was told to sand, sugar soap, rinse off. Then I used primer, a dulux emulsion (to make every thing white) and 2 coats of Johnstone’s vinyl matt emulsion. One son’s room looked great for some months and then crazed. This last week I sanded down all those crazes (it took hours).. today we sugar soap and then rinsed. At this point, we started to notice the crazing again. Not as bad but still there. I was planning on doing a mist coat, and a top coat of the vinyl matt again. but am thinking now should I use the Peel Stop and concede defeat. My son’s room is a very warm room and am worried it could still all craze again. Advise would be most welcomed please.

    Reply
    • Mike Cupit

      I’m not sure who you’re taking advice from, but it’s wrong. Sanding the silk prior to painting will make the issue of crazing more likely. Then the “primer
      ” just needed to be something flexible enough to cope with the expanding and contracting of the sile, then act as a barrier coat. People use guardz or soft sheen. The thing to do now would be to apply a full coat of peel stop, allow everything to dry off properly, then emulsion as normal

      Reply
  7. David Stainthorpe

    Hi there, after removing wallpaper from bedroom, the walls needed several lumps and bumps sanding from them. The walls were covered with emulsion / vinyl emulsion and I’ve broken through to bare plaster in places and scuffed the sheen on the paint where I haven’t. Could you advise me on what to primer the walls with before re-papering (lining paper then finish paper ). Many thanks.

    Reply

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