Help.. Trying to cover Polycell Damp Seal patches!

[JadeBrown]

About a year ago we covered over some damp patches with Polycell Damp Seal.. We had no problems at the time, and covered the white patches of the product with Magnolia paint.

However, this week we have painted the room with Wilko's Matt Emulsion in a dark sandy colour, and as soon as we did the first coat all the patches that we had covered with the damp seal showed through, and after the second coat they are even more obvious. The patches are really really obvious and look a lighter colour to the rest of the room, almost as if they are still wet if that makes sense.

Any ideas? I can't find any similar scenarios online.

Thanks in advance

 

[TheDec]

Paint over the areas with a thinned oil based undercoat.

Dec

 

[TheDec]

On reflection here are you sure that the dampness has not returned.

Dec

 

[JadeBrown]

I definitely don't think it is the damp, and in actual fact there weren't any damp patches as such there, there were in the other room, but we used this product on areas that had some bits of mould on, after wiping them down. We probably used the wrong product to be fair!

What do you mean by thinned? Sorry I'm a complete novice!

I'll try and put a picture on..

 

[elrobbo]

with out seeing the defects in person it can be quite hard to advise. another option is to use thinned down oil undercoat and apply to the whole wall. this will give a nice even constant layer of paint for your emulsion to go over the top.

thinned means applying white spirit to the undercoat and mixing it in. this will make the undercoat thinner in consistency and enable more area coverage and faster drying times.

 

[TheDec]

Thin the undercoat with around 5% spirit.

Dec

 

[JadeBrown]

Sorry, how do I post the pictures? I have uploaded two to my album

 

[TheDec]

There is no need whatsoever to cover the entire wall only the patches, just by using your brush feather out the edges of your undercoat. If however you feel that the areas are in anyway raised just lightly sand back the edges.

Dec

 

[TheDec]

I have seen the pics, just follow the advice with regard to the oil based undercoat and it's method of application.

Dec

 

[JadeBrown]

Thank you very much, both of you.. I'll go and buy the products and try this tomorrow. Fingers crossed!

 

[TheDec]

On the provision that the wall or indeed the patches are now dry and there is no further ingress of moisture, you should be fine. If you encounter any more problems then you know where we are.

Dec

 

[elrobbo]

just for future reference stay away from wilko's emulsion. it is worth spending a bit more and getting a decent quality trade emulsion. you will notice the difference.

 

[TheDec]

Trade emulsions are indeed the better choice.

Dec

 

[opps]

The damp seal will cause the paint (in those areas) to dry more slowly.

However I would have expected the finish to have settled after a 2 to 3 days without needing to do anything else. How long since the last coat?

 

[misterhelpful]

As opps says, the paint will dry more slowly when applied over the Damp Seal which will often 'flash' through the first couple of coats of emulsion (especially cheaper brands) so another coat may be necessary to completely hide it.
If you have allowed plenty of time for it to dry and the patches are still visible then Dec's method should solve the problem.