Blown Plaster

by Paul Coulson
(East London )

Hi Paul

I've found your guide to plastering very useful but despite the excellent advice we have run into a spot of bother.

Whilst painting the freshly plastered wall (left it to dry out for a good couple of weeks) parts of the plaster started to pull off. Having done a bit of research I've found out the term to be 'blown plaster'. I've read up on the Internet and various sources suggest taking off the blown plaster and re skimming the whole wall. My question is how do I stop the same from happening again? Research seems to suggest that the problem was a result of the plaster not attaching/bonding to the wall and that an application of PVA should remedy this. Is that correct?

Thanks
Paul

Hi Paul

Yes, that should do the trick! It may not have adhered properly in the first place in which case a physical key is needed. So therefore either apply plaster when PVA is tacky or if it may dry before you get to apply plaster then the addition of sand in the PVA mix will provide a gritty rough surface for plaster to stick to.

If it was a roughish surface then very high suction can risk the bond. PVA seals the surface and will ensure slower suction.Damping down with water can also control and slow down the suction.

Paul