Help!: tiles on, now they're off!

[jjcarroll]

Many thanks to doug, brian and paul who helped me with setting out last week. Tiles 40x25 were on the wall, hardibacker board in shower area and skimmed dot and dab everywhere else. Even a fussy old sod like me was happy...until I went to take out the tile spacers and one of the tiles came off the wall. That was it, further investigation revealed that all the tiles (exept those on hardibacker) more or less fell off on their own. What's going on? The adhesive was left on the tiles, looked a bit like putty. Used Sovereign tub, given free with tiles (was there a reason for that?) Perhaps I used too much adhesive? Or do I need to prime the plaster?
Looks like I won't be going out to play on my bike next week as I have to start all over again. Tiles are all cleaned up ready to go again.
Advice please.
1. Do I need to prime plaster?
2. What adhesive do you recommend?
3. How thick should I apply- new plaster but a few high spots, only 2-3 mm?
Many thanks
Jim

[tfs]

you need to prime first matey!

[Scott]

Edit: TFS beat me to it

PRIMER!

I wouldnt use that adhsive on that size tile either its too big for tubbed.

The only good thing about tubbed is you can reuse your tiles and clean them up easily as you have seen

[tfs]

if the wall isnt very flat the cement based addy would be better, ready mixed is not good for building up. With cemenet based you can fill fill low points and then tiles over once dry.

[doug boardley]

Hi Jim, yep you should have used bagged (powder) adhesive on those size tiles. Your plaster will need priming with an acrylic primer, whatever you do, don't let suppliers talk you into using pva either.

[Rich]

Prime (acrylic) and powder adhesive. The max bed thickness for tub adhesive is only 3mm and usually 10mm-12mm with powder.

What size trowel did you use?

[jjcarroll]

Thanks lads for all your advice. Just as well I'm retired and got nothing better to do (so the wife says!). Just bought some Mapei Primer G, is that ok? Have learnt so much just reading posts. I'm the sort who would have PVA'd everything but now I know better. Any recommendations for adhesive?
Thanks
Jim

[tfs]

Primer g will be fine mate

[tfs]

keraflex maxi or p9 both by Mapei (both are slow setting also)

[Daz]

If you have Primer G, which is manufactured by Mapei, then I would suggest that you use Mapei P9 adhesive. It is a standard set so should give you plenty of working time, just don't spread too large an area at a time and don't let the adhesive skin over prior to fixing the tiles.

[tfs]

In addition to what captain slow says, mix the addy regulary once mixed in bucket to keep it all good

[Saltire69]

If using P9, just give it a little mix in the mixing tub now and again. I feel it spreads a bit better doing this.

[Saltire69]

lol tfs beat me to it.

[Dave]

If you used tubbed adhesive and it hasn't bonded to the skimmed areas but has to the hardi then either the skim coat is over polished by trowel or it was slightly dusty and not adhered ... A wipe down with a damp sponge is sufficient for the plaster when using a dispersion adhesive but if the skim is slightly over polished then a stiff hand brush is required to dull it for the adhesive to gain capillary adhesion, do not over prime the walls or the dispersion will not stick..

If you are using cement based adhesive then yes prime to instructions on the bottle as this will then prevent ettringite failure.. Check periodically for coverage on the tiles but as mention above a cement based adhesive will be the one here..

[jjcarroll]

Am using a 6mm trowel, would you suggest bigger?
Again many thanks for all your help. Will have to let the thread go cold for a couple of weeks as I have other commitments and will return to the bathroom with renewed enthusiasm once I have forgotten about this week. I will let you know the outcome and hopefully post pictures of my success story.
Many thanks
Jim

[Dave]

I would use an 8mm..

[Rich]

As above, get yourself an 8mm