Tiling onto MDF

[Dave]

Hi. I'm building a fire surround using fire resist MDF. I know I can't tile direct onto the MDF, so I 'primed' it first with contact adhesive, let it dry for 2 days and then set the tiles. I'm using universal adhesive/grout (not good I know) and 6x3 wall tiles. Trouble is that I've tried twice to tile the surround and each time it looks like the adhesive has not set. I left the tiles for 4 days before trying to lift them but the adhesive is still 'wet' and easy to scrape off. Do I have to wait longer for the adhesive to set? Would a coating of PVA over the contact adhesive before tiling help? Cheers Brad

[John Stumbles]

I think you've said it: using ordinary water based adhesive (let alone crappy adhesive/grout!) is the problem: with the backing being impermeable due to your contact adhesive and the tiles themselves being impermeable due to being glazed the water has to dry out of the adhesive via the grout lines between the tiles which (a) will take ages (b) will give practically no adhesion as the tile adhesive won't bond to the contact adhesive.

[Tabby]

Silcone would stick them to mdf, but with no hard support the tiles would break very easily. I've no idae what will stick to dried contact adhesive, sounds like you've done yourself a mischief there. I wouldnt have used mdf either.

NT

[The Natural Philosopher]

there was your 1st mistake

That was the second..

And that was the third.

and 6x3 wall tiles.

It doesn't set, it dries out. That's what is crap about universal..

I left the tiles for 4 days before trying to

Best bet is to get GOOD adhesive that DOES set..recommend evostik waterproof, and leave it several days.

Then grout with BAL.

[Dave]

Many thanks for all the help. I've only just done the tiling and YES, evostik waterproof, i.e. Evostik ' Tile A Wall' waterproof adhesive DOES indeed stick wall tiles to MDF (and as stated in their tech specs). I landed up grinding the contact adhesive off with a Flap Disk and tiling direct to MDF. Brad