i have brought some wall tiles measuring 40cm x 25cm
can i use ready mixed adhesive or do i need a cement based one?

cement based.

what is the max size tile for ready mix adhesive?
also can i mix the cement based adhesive by hand?

hi. defo floor tile addy..fast set. just make sure the surface is sound..ie fresh skimming..is it able to take the weight of the tile. you should get a solid job,but a bit more work mixing addy,which will be worth while for a better job in the long run.wall tile addy..even non slip just does not do it on large format tiles . hope this helps mate.

Use a single part flexible powder mix adhesive, as rapid set will go off too quickly as the humidity is getting higher now, mix it with an electric drill / whisk ( paddle mixer ) clean off any excess of the tiles / substrate prior to it drying as cement based adhesive is tough to clean off if left. hope it helps Zahmed

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Natural stone specialists mosaic, porcelain and ceramics

humidity high!!. i know its warm but fu@k me. Get a grip. NO ADDY WILL GET ON THE TILE.....WE ARE CAREFULL

The bloke hasn't got a clue about what tile adhesive to use, do you really think he would be quick enough to use rapid set lol

judging from the comments i take it there are two diff types of cement adhesive: flexible & rapid set
i ask can i mix it by hand as i dont have a paddle & i need to do this job tommorow or the day after!
do you think mixing it by hand will be ok?
someone previously mentioned cement based adhesive is needed for tiles over 200mm x 400mm, as mine are only 50mm over that i thought maybe i can get away with the ready made stuff which would be easier for me

Once you get to a tile size of 300X300 it is right on the border line. I personally do that size and above with cement based.

I have 400X250 to do this week and they will be on cement based.

You get cement based adhesive which is rapid setting and flexible or non flexible. Slow (normal) setting and flexible or non flexible. cement based for mosaic use, large format tile use, stone use etc etc etc. That is why it would be best for you to ask in store.

You can mix by hand, if you wish.

Definitely a cement based adhesive. The bond strength is far superior and you will find it easier to trowel onto the wall. As ROC says, get it from a tile shop along with the free advice, not a DIY store. I would use Mapei Keraflex with a minimum 8mm notch trowel. BAL Single Part Flexible is another quality alternative. Once mixed, a bag of this slow set adhesive has a pot life the best part of the day. Dont try a rapid set, it will go off too quick for you. You can mix by hand but make sure its well mixed. If you're tiling onto gypsum, ie plaster or plasterboard, you should prime the walls first with Mapei Primer G or BAL APD. NOT pva.