Matt white washes off

UncleZen

I've painted a wall with Leyland Matt White emulsion. The reason I used this paint was that there is quite a strong colour on the wall and I wanted to lighten it up before the new silk emulsion goes on E.g. like a mist coat (also, I had some spare). To reduce the number of coats required withe the new, more expensive, colour. 
Now, when  I wash/wipe the wall with warm water, the matt  washes away and I can see the original colour underneath. 

Does it matter, if I am going to paint over using silk emulsion?
Should I seal it somehow, using pva or similar?
I've never encountered this before.
Any advice please on how to resolve this? 

neilmcl

Why are wiping down the wall with warm water that you've just painted? Also, what sort of paint was on the wall originally, matt or silk?

UncleZen

Wiping down the wall with warm water and a sponge 24+ hours after the matt paint has dried.
Original paint was vinyl silk.
Done some research since posting, and this is not an uncommon thing. And quite normal with trade matt emulsions (typically used on ceilings in dry rooms)

Doozergirl

The matt won't bond with the silk paint underneath, there's no surprise that it's coming off when you wash it, but more of a surprise that you're washing it at all. 

 If you have a preference for a type of paint, then stick to that one on each wall, don't mix them and expect them to work in harmony.  

I never understand why people use white to attempt to cover a 'stronger' colour.  White is a very strong colour in itself and isn't any easier to cover than anything else.  It isn't like an eraser, it's another colour to cover.  You're increasing the labour required, not reducing it. You're better off just using the appropriate number of coats of the new colour.  

I'm not a decorator, but in more than 20 years of renovating, much of those for a living, I've never seen anyone wash a wall after painting it!  Never put PVA on a wall to be painted either.  It prevents proper adhesion.  

neilmcl

UncleZen said:

Wiping down the wall with warm water and a sponge 24+ hours after the matt paint has dried.
Original paint was vinyl silk.
Done some research since posting, and this is not an uncommon thing. And quite normal with trade matt emulsions (typically used on ceilings in dry rooms)

You can't just paint matt emulsion on to a vinyl silk emulsion finish and expect to adhere. You need to prepare the original surface by either "keying" it by sanding it down, but this will take ages, or you can apply a water based primer such as Zinsser Bullseye 123, although this isn't cheap stuff but really good nonetheless.

UncleZen

I think, if I wash the matt paint off, then sand, then paint with silk emulsion slightly watered first coat, because ill need a few coats to cover the strong colour. should do it?

Doozergirl

No need to water it.  A mist coat is for fresh plaster where it sucks the water from the paint and prevents it from keying properly.  The misting is for a specific potential problem that you didn't have.  

Use the paint neat! 

UncleZen

OK thanks. But I think I'll get some zinsser bullseye123 to primer the wall after removing as much matt as possible just to be on the safe side. 

theonlywayisup

If you wall  is a vinyl silk and your desired finish is a vinyl silk, just paint in vinyl silk, using the colour that you want to achieve, with as many coats as it requires to give you the depth of colour you need.  

No need for white matt or anything else. 

UncleZen

Lesson learned! 
The only reason I used white was to lighten the strong colour underneath. Because recently I painted a brown wall with dulux silk magnolia and it took 5 coats to cover all traces of the brown. This is a similar scenario and I was hoping to do less coats

daveyjp

I did a similar job earlier this year, a darkish purple silk finish to white.

Keyed the silk using an orbital sander, which doesn't take long, it only needs a light going over. Base of trade emulsion, two coats of matt to finish.