Discussion in 'Tilers' Talk' started by J.T. Builders Ltd, Dec 9, 2007.
Do alot of tiling do you?
Cyril, hope you aint * talking about me there.
[Edited by: admin9]
I would turn the question round to you, MPR my friend, and ask you on what basis and on what evidence you assert that PVA should be banned from tiling.
Correct me if I am wrong, but I am unaware of any published evidence which demonstrates that PVA (diluted or otherwise) is anything but a satisfactory sealant on new plaster which has had time to dry thoroughly.
It is understandable that manufacturers should attempt to push their own products, but those who can think outside the box see through their cunning ruses and do not follow the herd blindly ...
murmac my friend. I do not dispute "that PVA (diluted or otherwise)is anything but a satisfactory sealant on new plaster which has had time to dry thoroughly."
Indeed, I have used it on numerous occasions when I have skimmed a wall with plaster. But never for tiling.
When you treat a surface with PVA it partly soaks in and partly sits on the surface of the substrate much in the same way as wallpaper paste.
If PVA gets wet it becomes slightly live again, it doesn't completely return to it's liquid state but it becomes sticky.
When you spread tile adhesive onto the wall, the water in the adhesive makes the PVA live and stops the adhesive from penetrating the substrate and providing a mechanical grip. Basically your tiles, grout and adhesive are being held to the wall by a thin layer of PVA.
Most tile adhesive works by crystallising when it sets (some are slightly different such as epoxy based ones) but generally they all work the same way. Once the adhesive starts to set crystals from and expand into any imperfections in the substrate surface (at a microscopic level) to create a grip. PVA stops this process by creating a barrier between the substrate and the tile adhesive.
Think outside the box mate & do the job properly eh?
thanks for that erudite and informative reply, MPR mate, but I still have a problem seeing why there would be any difference between sealing with BAL sealant (as you recommended earlier ) , and sealing with PVA. The BAL sealant is acrylic based, IIRC, but does it still not do exactly the same as PVA would do ?
I also have a difference of opinion regarding the "stickiness " of PVA when reactivated (so to speak) by water. My take on this would be that the length of "wetness" time ie the time during which the PVA would be exposed, would not be long enough for the PVA to deteriorate. Yes, I am aware that fully cured PVA can in fact degrade slightly when exposed to water, but my belief is that the tile adhesive would set and cure long before this would have any effect on a PVA sealant.
as you can see, I am a huge PVA fan ...
Bottom line for me is what do the adhesive suppliers recommend.
If they say PVA is OK, get it in writing and get on with the job.
It is probably not likley that tiles will fall off if PVA is used, but if you are doing a paid for (ie professional) job and you guarantee the work go with the recommendation of the adhesive supplier every time.
BAL will recommend the primers.
OK costs a few pounds more, but you can have confiidence in the job staying stuck.
> what do you guys do about tiling onto new un-painted
> Paint it?
> just tile onto it?
Shall we not fall out chaps? Lets just carry on doing our own things. Its like asking Angelina Jolie or jennifer Aniston? Utd or City? (ok it's always gonna be jolie and utd in my book but you know what I mean.
Yes, let us agree that in one corner we have a group of professionals and professional adhesive manufacturers suggesting that the right way to seal a wall is with an APD primer.
In the other corner we have two gentlemen from the Screwfix forum and a couple of low end adhesive manufacturers suggesting that watered down PVA is appropriate
Make your own mind up impartial reader of this forum
Around 5 years ago I went to a repair job that 1 of the lads tiled the week before. I had to remove some of the tiles he had put up to take a unit out.
when i took them off I only used slight force and the tile came straight off the wall leaving the plaster intact. I looked at the back of the tile and the adhesive had set to the tile and there was a skin ontop of the adhesive which was the pva.
when i removed all the tiles (leving the skim intact and totally untouched!!) i looked at the plaster and could see a few patches where the pva hadnt come off so i got my nail on it and it came off like thin clear sticky tape!
Since then Ive never used pva again after seeing what can happen 1st hand.
Just use good well know products and do what they recomend on the bag/tubs then if anything goes wrong you can fall back on the manufacturer. Some of the not so well known brands do still reccomend their own brand of pva so take a few mins just to ring them up and double check 1st
Read this thread it should make things clearer...
PVA ? NO!
And yes, I am shouting
As I said earlier in this thread
"NEVER EVER, EVER USE PVA. It should be banned from tiling"
And I'm shouting as well :-0
DO NOT PRIME WITH PVA!
That feels better, nothing like a good shout
"Ettringite failure".... must remember that for when I am faced with dodgy tiling.
" It looks like a bad case of Ettringite failure to me madam " :^O
god that jizzard reall spouts ****. He talks like a jumped up diyer. Probably never even done any tiling
Just for info, I had a concrete bird-bath that soaked up water, and so turned darker when filled. It just sucked up all the water.
The place i got it from told me to use waterproof pva top seal it.
I did. It had a couple of dry summer days to set.
When I refilled it, the water bath turned white and all sticky. When it rained, all areas I had pva'd turned white.
Took frigging ages to get it back to normal.
So. Waterproof pva ? Pffft!(ended up using Thompson's waterseal). Fine. (not that I'm suggesting using that on plaster for tiling)
Mr. Handyandy - really
I see admin has got rid of the handbaggers! Well done admin
you can run but you cant hide jizzer, i'm coming
Put your handbag away and grow up.
This is a mans forum, it's not for ********.
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