hello, you seem to be very knowledgeable and in a question about bath or something you said never skim on dry PVA? why is this please as i have had some problems on two jobs before and thought this could be down to my pva /skim timing! could you give me your preferred breakdown of over skimming on to both pva and over artex, thankyou for your time wise one
a question for roughcaster
- Thread starter spreadandlay
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PVA on it's own, when used as an adhesive/bonding agent, is only effective in its wet/tacky state..
If you let PVA on a wall/ceiling etc dry out , it becomes just a dry smooth surface, (similar to a coat of paint), a barrier with no bond for the plaster, and if you plaster etc onto it, it will not adhere, and eventually fall off...... If the PVA does dry too soon, just go over it again with another coat when your ready to plaster.
If you PVA a surface and plaster straight onto it while it is still wet/tacky, "it will bond"......
You can add cement, plaster or even sand to PVA to make a slurry to brush onto a smooth surface to form "a key", which you "would" let dry out first, before plastering etc........
With artex that is sound, knock off the high spots, coat with PVA, and again,while still wet/tacky, plaster straight onto it...........
As an aside,,, there are many people on here with a great deal of knowledge and experience covering all of the trades. Most of us do it for a living every day, and are only too pleased to share our experience and knowledge with those who want some advice, that can maybe help them solve a problem..
Roughcaster.
If you let PVA on a wall/ceiling etc dry out , it becomes just a dry smooth surface, (similar to a coat of paint), a barrier with no bond for the plaster, and if you plaster etc onto it, it will not adhere, and eventually fall off...... If the PVA does dry too soon, just go over it again with another coat when your ready to plaster.
If you PVA a surface and plaster straight onto it while it is still wet/tacky, "it will bond"......
You can add cement, plaster or even sand to PVA to make a slurry to brush onto a smooth surface to form "a key", which you "would" let dry out first, before plastering etc........
With artex that is sound, knock off the high spots, coat with PVA, and again,while still wet/tacky, plaster straight onto it...........
As an aside,,, there are many people on here with a great deal of knowledge and experience covering all of the trades. Most of us do it for a living every day, and are only too pleased to share our experience and knowledge with those who want some advice, that can maybe help them solve a problem..
Roughcaster.
thankyou for your time, i have been plastering for a few years now and always do it as per your method, however i have had a couple of spreads in to help me get through the work on a over skim job and they said it makes no odds to them if its dry or not! needless to say i found out the hard way they were a bit rough round the edges! i have recently started to add a bit of sand to pva before skim as i have found thid to be just as good as bond it stuff.
once again thanks for your time and its always good to be able to read up and compare experiences. one thing i know for def is you know your stuff, it is appreciated.
once again thanks for your time and its always good to be able to read up and compare experiences. one thing i know for def is you know your stuff, it is appreciated.
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Hi SpreadandLay,
Plastering onto dried out PVA is asking for trouble, unless some form of rough material has been added to it, (sand, cement, plaster etc) to help form a key. I plaster onto dried out pva/bonding coat slurry a lot, but dried out PVA on it's own, is often used as a sealer,,,, but "not" for sealing walls/ceilings etc, that are going to be emulsioned. Thank you for your reply above.
Roughcaster.
Plastering onto dried out PVA is asking for trouble, unless some form of rough material has been added to it, (sand, cement, plaster etc) to help form a key. I plaster onto dried out pva/bonding coat slurry a lot, but dried out PVA on it's own, is often used as a sealer,,,, but "not" for sealing walls/ceilings etc, that are going to be emulsioned. Thank you for your reply above.
Roughcaster.
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