Need help with this wall please

[Beard]

Hi,

I had this wall skimmed going up our stairs. It looks all streaky when looking from below during daylight, but fine when facing straight on or during evening under artificial light.


I'm not sure if the plasterer let the plaster go off too much before polishing or if my painting skills suck The wall feels nice and flat/smooth.

It has had an undercoat and 2 top coats of emulson.

Any ideas how I can fix it?


Thanks


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[TheDec]

It is'nt clear looking at the pic what has gone wrong here yet if the skim as you said was smooth it could very well be an application problem, you could lightly sand back and have another go, when you say undercoat do you mean mist coat.

Dec

 

[xr4x4]

Looks like roller marks to me, did you paint random, or up and down lines.

What paint did you use?

 

[Beard]

The paint was Dulux rich matt. Same as undercoat. Painting was pretty random I guess. Not sure what mist coat is.

 

[TheDec]

Dulux Rich Matt is not intended for use on bare plaster skim and this I believe is the cause of your problem, as a matter of fact I have heard terrible things with regard to this product. I think you should sand back until you have reached uniformity and choose another product.

A mist coat is simply a thinned coat of emulsion applied to the skim in order to form a bonding coat for future applications.

Dec

 

[Beard]

Ok, thank you.

What grade sand paper should I use and should I use a sander or is by hand enough?

Do I need to apply a mist coat once sanded?

Could you also suggest what undercoat and top coat paint I should use.

As you can see, I'm not a big diyer

Thanks

Dave

 

[TheDec]

When you applied you first coat of rich matt did you thin it down with water first.

Dec

 

[Beard]

No, just painted it on.

 

[Richard C]

Personally I’ve no experience of the suitability/quality of DRM as a primer, I only ever use cheap own brand matt white emulsion to mist prime newly plastered walls. Apply ordinary matt white emulsion, thinned 25-30%; I apply 2/3 coats in quick succession as I believe it gives better adhesion but others will advise it makes no difference. Priming new plaster is essential if your paint is going to stick to the wall (& remain stuck) in the long term. Insufficient priming will give poor adhesion & the paint will probably blister & start peeling eventually & if you stick wall paper over it, it will come off in sheets with the paper when you strip it.

If you didn’t mist/prime, it may already be too late; adding new paint over the top will not help & will just make things harder if you need to strip back & start again. If I were you I would put up with what it looks like for at least 3 weeks, let it dry out thoroughly & then do the selotape test for adhesion. Stick a piece of selotape on the wall & immediately peel it off slowly, if the paint peels off with the tape you’re in trouble; The patchiness is probably a result of the plaster sucking the paint dry too quickly.

By the way I’m not a professional Dec but am a plasterer. DO NOT use PVA.

 

[TheDec]

Rich Matt as I have said was not the correct product to be applied over bare skim, it really should have been applied over a plaster sealer and then thinning the system would not really have been required.

The reason I asked if you had thinned your first coat (mist) was to try and establish whether any bond between paint system and skim had been achieved, this now is not the case so your system although appears to be attatched in reality it is only floating.

What you now need to achieve is a way of breaking down this system thus allowing penetration of the next coat of paint. Other than complete removal your only other option would be to sand, if indeed you have to hand an electric sander then feel free to use it, not forgetting eye and mouth protection.

I would lean toward 120 grit paper and really hit this system hard you might find that whilst sanding areas of skim may be revealed, worry not it's far better to remove as much of the product as you can. When this has been achieved I would offer the walls a coat of Dulux Trade Supermatt although the recomended thinning is around 30% water I would tend to increase this by at least another 5 to 10%. See how you get on and post back if you run into any further problems.

Dec

 

[Beard]

Thanks alot for all the help.
This isn't recently painted, I did it a couple of months ago, I just hadnt got round to trying to fix.
I did the celetape test and it came off fine with no paint attached.

I'll give the sanding a go.

Thanks again

 

[Richard C]

This isn't recently painted, I did it a couple of months ago, -- I did the celetape test and it came off fine with no paint attached.

If that worked out OK after a couple of months of drying out then you should be OK; but your lucky, I’d consider that result a bit of a miracle. Perhaps DRM looks crap but has some secret ingredient

 

[Beard]

Didn't notice, but must have been paint on the selotape . I've got a big selotape shape left on the wall

 

[Richard C]

Didn't notice, but must have been paint on the selotape . I've got a big selotape shape left on the wall

 

[Beard]

Just to check as 120 is quite fine, do I need to remove all the paint?
It's a huge wall I wonder if I'm better off just getting it replastered?