PVA mix as a primer/sealer - How long does it take to dry?

Discussion in 'Decorating and Painting' started by taz999, 21 Feb 2005.

  1. taz999

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    Hi.

    I intend to use diluted PVA as a primer/sealer before I emulsion the walls. How long do I have to wait before I apply the 1st emuslion coat after I have applied the PVA mix. An hour, 2 hours, overnight, 24 hours ? The plaster is well dry.

    Will be using 5 parts water to 1 part PVA. By the way wots the difference between a sealer and a primer, if any?

    Any advice would be appreciated.

    Taz
     
  2. breezer

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    would it not depend on:

    ambient room temp

    absobtion rate of plaster

    thickness of plaster.

    try it tomorrow and see how it goes
     
  3. Panjandrum

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    You'll be able to tell by looking at it.
    Like breezer says, it depends on the conditions and how much you put on.
    But if it's inside and warm and ventilated and you start NOW it should be OK by tomorrow night :) :)
     
  4. confidentincompetent

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  5. jbonding

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    i agree with con all the painters on site water the emulsion down for their first coat on fresh plaster.
     
  6. taz999

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    Thanks for your reply guys. Guess I should have provided a bit more info:

    90% of the house has been skimmed over the exiting old plaster/wall. There's small areas which have been plastered over platerboard and other small areas plastered over bonding coat.

    There is heating in the house, but I dont I will have much ventilation this week as I cant find my thermals :p

    I have painted the ceilings in a couple of bedrooms. Here I decided to go for Polycell crack free ceiling paint. Didnt have any cracks up there, but hopefully that paint will ensure I dont have any in the future. However noticed one or two hairline cracks here and there in other parts of the ceiling both upstairs and downstairs. So I will continue to use it throughout the house.

    In the bedrooms I used 50:50 emulsion/water primer. Now, (dont laff people) wasnt sure whether to use the Polycell in the primer mix or some cheap, no-frills emulsion. The latter option would have saved me a few pennies no doubt. Decided to use the Polycell in the mix in the end, on the basis that it would adhere better and do a better job (no cracks in future) to the ordinary emulsion water-downed stuff. Now is this totally flawed logic on my part? Can I get away with using the cheap stuff in the primer?

    Also when applying the above primer, found it going off very quickly on the ceilings. Poss a good thing as I then apply the next coat?

    I just happen to have a large PVA bottle lying aroud that was purchased only recently. Was thinking of using this, also I find mixing this stuff up and working with it less hassle than watering down emulsion. I find it easier to produce a smooth, lump free PVA mix than emulsion.

    Just had a guy wallpaper the bedroom wall. He's a professional decorator and it was he who suggested the PVA option. So now, im confused ! Is the emulsion based primer better than the PVA mix or is it just people's preferences? Are both methods equally valid?

    By the way, I applied a further two coats to the bedroom ceilings after the primer, and they look the dog's dangly bits. :cool:

    Pressure is on. The site manager/project manager/supervisor is hassling me to get the job finished as soon as. And If I dont she's refusing to cook any more meals for me!

    Cheers,

    Taz
     
  7. Panjandrum

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    Taz,
    My preference for PVA comes from experience with an old house (1896) with external rendered walls and some dubious bits of lath and plaster inside.
    Inside and out I like a thin PVA coat on any untreated bits to give a good grip for the paint.
    Externally I wash and brush down then PVA everywhere before painting. It's really quick. Lasts a good 8 years outside - re-painted when the designer says so. Next door, same house, gets re-painted every three because their paint is flaking off.
    That might be the difference between primer and sealer? Primer preps the surface for painting; sealer does that and also stops helps the paint cling on? Or maybe that's just rubbish.
     
  8. confidentincompetent

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    Taz m8 you got me confused now :confused: How do u manage to get a lumpy mix with water/emulsion :?: Has it been in freezer :?:
    I never use pva on bare plaster and been doin it like that for last 30yrs
    and my arm dont arf ache :LOL:
    Use normal emulsion (matt) for primer, finish with crack free if you want but this takes 24hrs between coats to dry if you put it on thick as it says on can. Has to be thick to achieve thick flexible film.
    godd luck.
     
  9. SteveOfKemble

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    WARNING: I recently sealed a bare wall before applying Crown emulsion, as advised to do on the can, but I used PVA, as I have always done. Take the advise of "confidentincompetent" and use dilute emulsion.
    What happened to me was that when using a roller to apply it, it kept forming little bubbles which stayed until it dried. I now have to rub it down again and apply a second coat. When I suggested to Crown that they warn against this, they refused and placed the blame on PVA.
    I have not tried the same with Dulux.
     
  10. francspencer

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    water down matt emulsion 50/50 for 1st coat.
     
  11. Robbie uk

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    DO NOT USE PVA AS A SEALER BEFORE EMULSION !!!!
    Dilute emeulsion is all that is needed.
     
  12. LJW61

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    As Robbie says ..PVA a no-no !
    As for the thinning, I dilute 25-35% water
     
  13. igiveitup

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    I have foolishly gone and used PVA as a sealer on the ceiling, and having major problems getting the emulsion to cover, as it's very patchy. Have sanded it tried again, and just sanded it again.

    Now there are patches of bare plaster, patches of feint white with pink plaster showing through and just one big ugly mess.

    Can anyone please help how to make this good other than lining the newly plastered ceiling?

    Help would be much appreciated
     
  14. LJW61

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    Just paint the whole ceiling with an solvent/oil-based undercoat , thin it slightly and apply with a foam/sponge roller & it will seal itb ready for a few coats of vinyl matt..Buy trade emulsion, not Wickes,B&Q etc.
     
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