a while back, everyone said porous surfaces should be sealed with pva, but now its a big NO NO! PVA is bad stuff now!
Ive used it for years & years & never had a single problem!

Check this thread out, it might help you...if not continue to use it if you so wish but we don't advise it , along with many tile adhesive manufactures..........

http://www.tilersforums.co.uk/tile-a...s-primers.html

Yes I was suprised as well !


I was always told to unibond everything with a thin coat. But it seems thinking has changed as the thread above explains.

Funny how fashion changes.

Drink-a-pint-a-milk-a-day

Go to work on an egg...

Smoking does you good !!





What a funny world we live in !

i used to use pva all the time and never had a problem with it buti have taken the advice of the more experienced tilers on this forum now i always prime

Never used it.

PVA ,prime bond and seal.
I know quite a few who still use it.I use to.
Funny how things change.

I'd never even heard of using PVA instead of primer until I got onto these forums

I think the main problem is the term "PVA" the meaning of this acronymn is POLY VINYL ACETATE alot of people use the term to describe various products from ardion 90 by ardex to unibond or bondcrete as it is called down here. The latter 2 examples are not poly vinyl acetates and are used with various types of cementuous products with certain applications. They still should not be used as primers as they will only coat a particular surface they won't penertrate it as a true floor or wall primer does.

The 2 key problems in using poly vinyl acetate as a primer are:

1. once applied pva can reabsorb moisture be it from your adhesive or in a wet area causing it to let go of the substrate with a resulting tile failure.

2. Some adhesives may cause a chemical reactions causing the acetate in the "PVA" to form acetic acid. Not a major problem say under ceramic but under any type of stone it could mean trouble.

On this forum techniques and syles will always be changing as new cases of problem tiling occurs. The pros that fequent these pages including myself endeavor to keep up to speed on such topics to form sound opinions which hopefully leads to sound advice and in short I believe we all do that.

I am pleased to here that certain people who use "PVA" have not had any problems and that's fantastic. But sadly there are cases that counter these claims and we have to listen to these as well and give advice based on a worst case senario. For if we recommend a product and it fails we let down our fellow members and lose respect within our industry.

For the moment until further notice I and some of my fellow pros do not recommend the use of "PVA" as a primer because as far as the data and failure rates suggests, it's use would not warrant "BEST PRACTICE" within the tiling industry.

Do yourself and your fellow members a favour and only use the recommended primer for the recommended task.

Cheers Mick

I obviously agree that 'PVA' is not suitable and have never used it for tiling priming. If anyone is in doubt, whichever adhesives you are to use, phone them and ask which type of primer they recommend for their adhesives, this way you are covered in the event of a failure.....Gaz

on most adhesive tubs whether it be bal, nicobond,weber,dunlop etc most of them recommend priming