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QuestionWhy is it that I apply two coats of PVA to a ceiling or wall that after a certain time it starts to reject the skim


10 Answers

The correct mix for pva for plastering is 1 part pva to 5 parts water, and really only used to stop the plaster drying too quickly, plastering over silk paint with or without pva can only be as adhering as the paint before, pva doesnt make the plaster stick to the behind of a painted surface!
kind regards
Dave

McLarren property maintenance 14th Mar, 2011

its best to wait until the 1st coat of Pva has dried or put it on the night before and then apply the 2nd coat (depending on the type of wall).you then skim the wall or ceiling when the Pva is sticky (NOT WET) as it will just drag the plaster.hope that's what you meant

Finished Homes 17th Feb, 2011

this some times happen if walls and ceiling are painted with a silk finish so any paint like mid sheen full sheen and vinal silk no matter how many coats of pva you put on it wont make any difference you would have to bond the walls and ceiling first.

SDW Property Maintenance 17th Feb, 2011

you only need to apply a second coat of p.v.a on mid to high suction backgrounds when the plaster will more likely dry faster.on silk paint and shiny surfaces apply one coat and wait till tacky.

Alchemy Plastering 27th Feb, 2011

because it will be like skimming glass ,plaster it when its taky

dpfplastering &screeding 28th Feb, 2011

You dont need to pva plaster board,Only on high suction walls and for over skimming its best to pva day before and 2nd coat just before skimming, let it go tacky before skimming, dont let 2nd coat dry out before skimming.

You shouldnt have any problems, make sure plaster is not out of date, some are, and always use clean water

B J D BUILDING/ROOFING 17th Feb, 2011

Maybe your not applying enough PVA ..? should be mixed 50/50 with water.. so quite thick, should not need two coats, also can depend on how you apply the plaster i suggest a wet mix and always use multi finish

The Hayfield Building Company 17th Feb, 2011

Hello,I can only assume you are trying to apply plaster on to a p.v.a'ed surface that is wet as opposed to tacky. In my experience it is the sealing of surfaces that is most critical,where possible sealant should be applied(really lather it on)the day prior to plastering.If a surface is properly sealed you may not need to put on p.v.a as an adhesive(artexed surfaces for example)...Barry(finbar)

B.P.O'Connor plastering 20th Feb, 2011

never seen that. maybe the pva is bad. or greasy walls,cellings or might even be nicotine. but probarly the pva. as the brand new unibond i had in the back of my van turned into a solid lump in the cold... ive just reread it i think i know what you mean. if its when the skim is drying out and starts to fall of the surface and leaves patches....well you cant plaster wood, smooth concrete, and vynal painted surfaces. you need to scrape the painted surface and apply a splatadash coat for a key and wood needs meshing.

northview property mainenance 17th Feb, 2011

This can happen in victorian houses which have been painted with distempa (im not sure how you spell it!) It happened to me once (never again!) you have to apply PVA let it dry completely, a couple of times to completely seal the ceiling then apply a coat just before skimming, let it dry tacky. I have also added a small amount of PVA to my thistle which didnt do any harm.

NR Building Services 19th Feb, 2011

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