Painting matt emulsion over silk CAN be an issue at times, but not always. I’m all over decorating forums, and even professional decorators are split in their opinions, many of whom have never experienced problems.
However, some of us have. In this blog, I’m going to talk you through the possible pitfalls, the process you should take, and the solution to any problem that may crop up.
Why Painting Over Silk can be a Problem
I’ll give you the science behind it. Silk emulsion is very flexible, and matt is generally quite brittle. When you paint over old silk with any type of water-based paint, you’re essentially rehydrating it. The silk then expands and only contracts after your topcoat has dried. The silk can handle the expansion and contraction quite well because of its flexibility, but an emulsion such as matt cannot.
So, as the silk contracts, the matt cracks with the strain of the movement. This cracking is called “crazing”. I have painted matt over silk many times and only experience this issue every now and again.
How to Prevent Problems When Painting Matt Over Silk
There are certain things you can do to minimise the chances of crazing. The first thing you can do is choose a topcoat with some flexibility. Avoid using cheap contract matt or retail, as this type of paint does not contain much binder so dries extremely brittle!! Use a good quality vinyl matt emulsion instead. Avoid Dulux too!! It may just be the luck of the draw, but every time matt paint has crazed on one of my jobs I’ve been using Dulux Trade.
Another thing you should avoid is sanding your silk before painting over it. This contradicts the advice you will get from some other decorators because we’re hardwired to sand everything to prevent problems, but trust me, I’m right. If you sand walls painted with silk, there is more chance of the water from your new paint soaking into it and the silk expanding.
The other thing you can do is use a barrier coat. This is quite a simple idea; you coat the silk with a flexible paint which acts as a waterproof barrier between your matt and your silk. You could use mid-sheen emulsion, eggshell, Zinsser Gardz or Peel Stop. You can buy Peel Stop online by clicking here. Whatever you go for, you will need to give it long enough between applying the barrier coat, and your matt paint. Preferably overnight, or longer if the room is cold.
How to Fix Problems Which Arise After Painting Matt Emulsion Over Silk
OK, so you’ve painted your matt paint over silk and now you’ve got mud cracking and crazing all over your walls. Don’t panic!!! There is a simple solution!! The first thing you should do is sand all your wall space. This will not get rid of the imperfections all together, but it will make it easier to cover.
The next thing you should do is apply two full coats of Zinsser Peelstop. This will do a couple of things. Firstly, it will cover minor imperfections such as cracks. The other thing it will do is act as a barrier coat between what is on the wall at the moment, and the paint you’re about to apply. Again, leave overnight for everything to dry before re-painting.
Is matt or silk better for walls?
If after reading this blog you’re still considering painting your walls or ceilings with silk, don’t! I think just about any Decorator will advise you to avoid silk at all costs. Not only does it cause problems further down the line when you come to paint over it, but the finish is never very good.
Silk shows defects such as flashing and picture framing. It also highlights imperfections on plaster. Besides which, a “deep matt finish” is much more desirable.
The only reason you might be tempted to go for silk paint over matt emulsion is for durability reasons. Silk is waterproof and wipeable, whereas vinyl matt is not. You could go for a durable matt emulsion instead, which gives you the best of both worlds. Or acrylic eggshell is a step up in durability again and doesn’t give you the same issues you get with silk.
Can you paint over silk emulsion without sanding?
Yes! If you are painting matt over silk, then I’d advise doing it without sanding. Sanding will only cause more issues. Providing the silk is dry and you’re using a quality product to paint it with, you should be fine.
Why is my silk paint Emulsion bubbling?
Nightmare!! If your silk paint is bubbling, then it’s because it is expanding and coming away from the surface underneath. It usually sorts itself out, but if not, you may need to remove all the silk with a wallpaper seamer before you can decorate.
What to do if your silk paint starts peeling?
If your silk paint starts to peel from your walls or ceiling, then the only real fix is to remove all the silk. Even if you did manage to paint over the existing silk and it holds, you will probably encounter the same problem when you come to redecorate further down the line.
This issue is normally due to an incorrect primer being used, or painting over chalky matt emulsion. It’s a problem with adhesion. You can strip silk from plaster using a wallpaper steamer. Click here to see online prices.
Can I change a matt-painted surface back to a silk finish if I change my mind?
Painting silk over matt emulsion is only ever an issue if you’re painting over cheap contract matt, in which case you might have adhesion issues. However, I don’t know why you’d ever want to. Silk emulsion looks horrid and can cause issues.
If you prefer a little bit of sheen on your walls or ceilings, then opt for acrylic eggshell instead.
OK, I hope the above blog has helped you to understand the issues with painting matt emulsion over silk. The important thing to remember is not to panic if you do experience a problem. Just know there is often a simple solution.
The greatest bit of advice I can give you is not to rush anything. Leave every coat of paint as long as possible before applying the next. Providing you do that and follow the other steps above, you should be fine. Click here to learn more about Zinsser Peel Stop.
Painting Matt Emulsion Over Silk – by Mike Cupit
What do Other Decorators Think About Painting Matt Over Silk?
From my experience, painting over silk risks crazing. This cost me 2 days on a job once, so now pre-empt it and treat all silk same and a coat of Gardz after basic prep.
Light sand and get the matt on. I’ve never had any problems
99% of the time you won’t have any problems. The trick to painting matt over silk is to avoid sanding the silk before you start. If you do get any problems after your first coat of matt, just sand everything down and coat with Zinsser Peel Stop.
You don’t need to overcomplicate anything. There’s always a simple answer.
Whatever you do, don’t sand it down!!! Put a coat of contract matt on the silk first.
In 31 years, I’ve never keyed or primed silk emulsion. I’ve always just used decent Matt and never had a problem.
Apply a mist coat, then two full coats of matt emulsion. It’s easy peasy. Don’t sand the silk or you’ll have issues with it bubbling. Let each coat dry fully
If you do have a problem with crazing when painting matt over silk, it’s dead easy to sort out.
Sand, apply a coat of Zinsser Gardz, paint, filler, sand, touch any filler up and then final coat. See too many people post about problems on the Decorators Forum UK. I always use Zinsser Gardz now.
If sanding, only very lightly or it’ll come off in sheets and create more work. I normally just give the silk a coat of Zinnser Guardz to be on the safe side, then at least the Matt has something to bond to.
Every time I’ve painted matt over silk, I’ve had some sort of problem regardless of prep. Sometimes the bubbles go, sometimes they don’t.
Now I normally have to Zinsser BIN or undercoat / barrier coat. I often now I’ll get the BIN tinted in the wall colour and use that for the first coat.
I hate silk with passion. Sometimes when painting over it, it can start to peel you need to scrap it back to bare plaster.
Anyway, giving a quick coat of acrylic primer undercoat straight into a bit rubbed silk is helpful. All repairs/filling after the coat of acrylic undercoat.
I have not had any problems after sanding, dusting off, and using a durable matt straight on top of the silk.
Speaking from my point which is mainly a time saving speed approach to get a solid white over any silk.
First give the silk a light sand.
Then graffiti spray (yes) any bare plaster bits to avoid the silk edges bubbling up.
Light coat of matt (adhesion coat).
Solid thicker coats from there on.