Matt Cracking and Crazing Over Silk – the Cause

Updated May 10, 2023 | Posted Aug 28, 2018 | Professional insight, Tool Insight | 12 comments

Matt cracking and crazing over silk emulsion is common problem that gets brought up on Decorators Forum UK. So much so I thought I would write an article about it to help fellow decorators should they encounter the issue.

 

What Causes Matt to Crack and Craze?

 

The cause of this is down to the substrate being a ‘reactive’ surface. Now by this I mean that when it gets wet it can soften and expand. It isn’t just silk that it happens with, it happens with surfaces that have old paste residue, thick PVA, or even cleaning products.

The cause of a matt paint cracking and crazing over silk or a similar surface is; as the matt paint is applied over the top, it softens the silk causing it to expand, then the matt dries on the surface first, then the silk underneath dries and contracts causing it to pull the matt apart (crazing). Like the pictures underneath. This doesn’t happen EVERY time you paint matt over silk, so if it hasn’t happened to you then you are one of the lucky ones, but it all depends on how reactive the substrate is. This could be down to quality/how thick the silk is as to how much it expands.

If something you have painted has done this, there are a few solutions to prevent or solve the problem. I personally use Zinsser Peel stop. (click here to see online prices). It is specifically designed amongst other things to seal cracking & Crazing (see pic below). I never use this as a prevention, but only for a cure.

This is because crazing over silk doesn’t always happen, so I take my chances to prevent unnecessary extra work. There are a few other suggestions that pop up on the forum to resolve this like ‘Use soft sheen as first coat’ or ‘oil undercoat’ but I see this as a more costly resolution. However, uing a barrier coat is a solution. You’re simply blocking moisture from coming into contact with the silk, thus preventing it from expanding.

While spending months scrolling the internet researching this problem, I decided to carry out an experiment myself on 3 different jobs painting matt over silk.

I’d read somewhere that rubbing down the silk could cause it to be more reactive, so on each job I rubbed 1 wall down before coating the first coat of matt. On each job the 1 wall I rubbed down crazed and the others were fine apart from one, but was nowhere near as bad as the one wall I rubbed down. So personally I’d suggest if you are painting over silk, get the first coat of matt on it first then rub it down, as it clearly softens the silk more by doing so. Click here to see online prices.

Matt Cracking and Crazing Over Silk – A decorator

What do Other Professional Decorators Think?

I have never used peel stop, but there is a similar product made by Zinsser called Gardz. I apply a quick coat of it on the silk walls before I paint over it with any matt product. The only issue is, you’ve got to wait 3 hours before you can paint over it or it’ll craze anyway. I think I’ll give the Zinsser Peelstop a go on my next job.

Andy Marks - matt cracking and crazing over silk

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Thought I was going “crazy” yesterday or whenever it was when everyone was saying that it was perfectly fine to go over silk with matt. I suppose most of the time you probably can get away with it without having any issues, but I’ve slipped up a couple of times now.

I think Zinsser gardz is probably your best way forward. You can use it to prime silk before applying matt, or you can use it after the matt has already crazed. It seems to get into all the little cracks and fills them, as well as becoming a barrier between additional coats and the silk.

Mike Cupit

If you seal the crazing with the Gardz or peel stop after it has happened, you won’t need to fill any of the cracks. All you need to do is apply topcoats of emulsion. Just make sure you give it enough time to dry properly. I think recoat is 2 hours, but I’d give it at least half a day to settle down.

Owen Tierney

Some great advice in this blog. The issue of matt crazing over silk or wallpaper adhesive isn’t one you come across very often, but when you do, you need to know how to deal with it. You should always try to apply thin coats of paint when going over silk. Then if it does start to craze, just apply one big coat of Zinsser Gardz or Peelstop and you’re good to go

Mike Gregory

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Matt cracking and crazing over silk can be a nightmare at times. I went for years as a decorator without it happening, but it’s happened three times in the last six months. Zinsser Peel Stop has worked as a fix, but it’s still a faff.

Now I coat the walls with Zinsser Bullseye before I start now. It acts as a barrier coat to protect the silk from expanding.

Tom Comp

Updated May 10, 2023 | Posted Aug 28, 2018 | 12 comments

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12 Comments

  1. Wayne Salvage

    Very useful and helpful information. Have not had a problem like this yet, but good to know a remedy if i do. I don’t know everything so it’s good to find out these things. Thanks for the information

    Reply
  2. Jit Snibler

    Great help thanks for the advice

    Reply
    • Liz

      I have painted Matt emulation over vinyl silk which has not adhered evenly, what can I do now

      Reply
  3. kim stockwell

    Hi, what about silk on top of matt, do you get the same problem ?

    cheers kim

    Reply
    • Mike Cupit

      You should be ok to paint silk on top of vinyl matt

      Reply
      • kim stockwell

        Thanks Mike.

        Reply
  4. caroline oliver

    Matt over silk wiped walls pain has nIve pained my kitchen i think hubby used silk years ago he cant remember !! Any way 2 coats dried but it wipes of with a wet cloth, should i prime coat the wall and repaint after its dried ?

    Reply
  5. Nadia Azad

    I sanded down my silk wall then cleaned them down I have painted Matt on top but because of panels on the wall it looks like I missed some areas with have slight cracks wat can I do and can I repaint over with silk

    Reply
  6. Kieran Maguire

    Hi

    I’m a DIYer and found your page whilst desperately searching the internet.

    I’m decorating our new house (1960s) and one of the bedrooms has been painted really sloppily with silk paint, underneath this last layer is a layer of white matt.

    I’ve been trying to sand down the lumps/bumps/paint marks to get a nice smooth blemish free wall, fill in any holes.
    Sand it all smooth and then paint on top with matt paint of dif colours (it’s a 6yr old daughters bedroom).

    It’s my first experience of silk paint and it’s proved a nightmare so far.

    In the past it takes me minimal time to sand the walls flat, fill in any blemishes, then sand those too. So I have immaculate Kendal mint cake smoothness to paint on.

    The silk paint seems to be stretching, peeling (leaving ugly ridge marks) and the feel of it is horrible afterwards. The time taken is 3 days so far.

    I’ve tried sanding with various grits, washing the walls with sugar soap, letting dry & sanding again, all I get is wierd rubber lumps on my sander I have to pull off, stretchy plasticy split level looking areas of a max size of 4cm getting through the silk paint top layer and mess.

    Have also tried a heat gun just now in sheer desperation on a small patch, and that’s also not worked.

    Can anyone help, I’m so desperate.

    What had always been a fairly quick job of preparing the walls before painting is taking days, with bubbles of the top layer of silk paint no bigger than4cm coming/peeling off in patches sporadically- It’s like cling film has been glued over the walls & is coming off in tiny tiny bits, not sanding smooth, stretching like bubble gum.

    Painting over the walls in this room isn’t an option, it’s lumpy bumpy, marked all over, and raised paint/brush strokes are visible from 10 meters away. So needs filling in parts, all sanding smooth first before painting

    Thanks for your help

    Reply
    • Mike Cupit

      I’d be tempted to just line the walls if it was me. Sounds like an absolute nightmare

      Reply
      • Kieran

        Update
        I’ve got a steamer and it’s working, albeit slowly.

        It’s alittle like peeling sunburnt skin. Sometimes you get big bits and other times it doesn’t want to give it up.

        I think it’s been painted inconsistently from the beginning from looking at it. The first watered down paint seems patchily done, then it’s had a top up of matt white. Then a purple silk? Then a magnolia silk? All slapped on by the look of it so its gone lumpy bumpy and complete with tiny lumps too.

        Be great once steamed off I can sand it, fill up the gaps, sand again, do a watered down first coat, then likely a few matt coats and should be done to an immaculate finish (hopefully).

        Epic painting job. Not sure if it’s abit OTT but I’m an amateur and hoping done once, done well, won’t need doin again till sometime down the line.

        Reply
  7. Keith Mays

    Hi
    I need to paint matt over silk on 1 wall.
    I still have some Zinsser peel stop from a previous job.
    If I give the wall a quick sand then paint peel stop on the silk, then apply the matt will that stop the cracking?
    I’m guessing peel stop and gardz do the same thing?

    Reply

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