Painting Too Soon?

jasgrif11

Hi,

House is plastered about 6 weeks and the painter started last Thursday. It took him and his crew one day to completely spray the whole house (walls and ceilings) with a coat of white paint. It all looked fine until Monday where I noticed a lot of patches on the wall it looks as if some paint has peeled off the wall (when it hasnt) One room especially has layers on the wall, effectively it looks like a jigsaw.

What is the reason behind this? Is it because he painted it too soon. Also whats the best method of fixing it. The plasterer reckons that it was painted too soon and the three affected rooms will need to be sanded down wait for it to dry out and then reapply the paint with some poly bond mixed in.

Has anyone seen this and how did you fix it?

Thanks
J

RKQ

Is it the paint or the plaster?
It sounds like "mapping" to me.

This is where the plaster is overworked by the pPlasterer, as it drys.
It creates a patchy glaze to the plaster when painted, looks like countries on an atlas, so its called mapping.

Hard to remove, sanding will help. But 2nd or 3rd coat of paint hides it.

6 weeks to dry out isn't bad in a normal summer, but its been very wet and damp with very poor drying. They use to recommend not painting for 6 months, but thats rare since the boom. Everyone wants instant perfection.

I'd assume that paint sprayed on wall is quite thin paint. ( I could be wrong) Maybe a few extra coats of paint will solve the problem.

jasgrif11

Thanks for the reply. Yes it looks like mapping. To try and explain it further.... it wasn't noticeable when first applying the spray. Only after it has dried can you see a perfect smooth surface and in areas its as if a patch was taken off the wall but beneath it is also white.

Thanks
J

Wertz

Definitely mapping.
Whilst plaster may not be 100% cured at a deeper level, the first few mm from the surface should be fit to take paint without a problem. If it were dampness I'd be expecting to see staining, flaking and effloressence.
Whilst it is the plasterer that has caused this problem (it's something a lot of them do and never get to see the results of) it's up to the painter to put right, either through additional coats and/or through use of stain blocking coatings. Sanding isn't really going to help here...the problem is in the underlying plaster...sanding will only remove the paint whilst still leaving you with the problem
Mapping can effect a sheened finish as the areas that are "shiny" (through over trowelling and/or the use of morticiser additive) can take longer to dry than the adjacent plaster...this can lead to a noticable difference in the finish on the walls when the whole paint layer dries. There may also be problems with adhesion of coatings to the mapped areas...

Polybond :rolleyes: the plasterer's answer to everything...

Kernel

Did they PVA the walls after they plastered? Found the paint goes on nw plaster a lot easier once you apply a few coats of PVA.