I know ive asked this or something similar before but its been that long i could do with a refresher. A job that should have been finished months ago, will i hope be getting done shortly. I have quite heavy wall tiles which are close to the weight limit recommended for going on to plaster skimmed on to plasterboard. Would i be better tiling direct onto the bare plasterboard, doing it this way means the weight limit has a fair safety margin. I was advised to use "bal APD" as a primer would this be ok painted on to the bare plasterboard. I am going to be using a water based adhesive, i know there is a danger that the adhesive wont totally dry out under large tiles but the tiles are pretty porous. Anyway the speed i tile at should give them plenty of time to dry. The question is though does bal APD only slow down the water absorbtion rate or does it totally stop it. I dont feel confident enough to use the adhesive you mix yourself as i would only get a couple of tiles up before it went off.