Acrylic

[quick draw macgraw]

Hi,

I've heard most of you say if in doubt prime it out and i agree but with say bal blue star on kitchen splashback if its acrylic based addy do you not have to prime it in theory? Yeah it wont do any harm but is this just being doubly sure.

Cheers Steve.

[Fekin]

Most probably.

Only time I ever prime is when using cement based adhesives on plaster, and heavy tiles on painted walls after roughing up the surface.

Primings a bit like tanking in showers.
Some people prime most substrats like some would never do a shower without tanking, it all comes down to the tilers choice of doing things.

[Dave]

acrylic adhesive will stick to plaster no probs as long as you brush it down to get any dust of the wall...but if you are going to spend time brushing it down you might as well prime it to make sure it is dust free..also priming stops the addy drying to quick in case you need to make adjustments.........

Bal reccomend wire brushing highly polished plaster and priming.They never used to advise this, but some 15 years ago there was ,alledgedly,a major change in the make up of certain plasters which was causing a reaction with adhesives, and tiles were popping off. The problem with a highly polished surface is that it is compacted dust,and therefore not a stable surface to tile to. I always sand down plastered walls and prime. I am probably on my own in this respect,but i like to play safe. Is Bal on their own on this wire brushing suggestion?

[Dave]

spot on len it is best to sand or wire brush a polished plastered surface to provide a good key for the adhesive...

[NETT Darren]

When adhesive drys it crystalises and the crystals expand out into the inperfections of the walls, when a plaser is polished and dense there isnt the imperfections to latch onto therefore requires a bit roughing up and acrylic primers. If your using a cement adhesive there can be a chemical reaction and a substance called ettringite is formed, this can cause failure between the plaster and the cement, The tiles will become a rather messy mosaic on the floor

beware assuming that the same brand primer as the adhesive will do. For example. BALs APD is the primer for using cement based adhesives, but their Bal Bond primer is,as far as i am aware, not suitable for this purpose.

Originally Posted by len

beware assuming that the same brand primer as the adhesive will do. For example. BALs APD is the primer for using cement based adhesives, but their Bal Bond primer is,as far as i am aware, not suitable for this purpose.

GOT TO MAKE A RETRACTION ON THIS. Spoke to BAL Tech. today. Bal Bond IS suitable as a plaster primer for cement based adhesives, it states so in the first sentence on the back of the bottle.They are aware that they have omitted it from their spec. sheet. APD though still suitable for the job, is now the primer for their WPI tanking and for priming bare floorboards to prevent them from warping as the adhesive sets.

[Dave]

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