Preparing existing plasterboard and plastered walls for tiling?

[Wh15ky]

I am in the process of preparing my bathroom walls for tiling. I have stripped off the ugly 1970s wood style veneered crap and scrapped of the glue etc. I am in the process of sanding down the walls (to rid any flaky bits) and filling any holes and cracks.
2 walls are plaster on brick and 2 walls are plasterboard, I'd like to know what I use to prime them, same product for plaster and plasterboard? Is Mapei Primer G suitable and do I scratch the surface of the walls before applying?

[Fekin]

It's only really when using cement based adhesives you need to prime the plaster as cement based adhesives react against the compounds in plaster, so on just boards you don't have to prime, but you might as well if your doing other walls that are plastered, as it dries tacky and gives a bit more stick, so to speak.

Any acrylic primer is good, some have their own personal favorites.

[Wh15ky]

Thanks for the advice, would you know if the Mapei Primer G is acrylic, as I have seen that one on the Screwfix website and I will order it from there.

[Fekin]

Yes, I've never used it but it's the same as Bal APD, so yes.

[Dave]

screwfix are expensive for primers...try your tile shops.....prime plaster board as well as plastered walls...it will stop the sticky drying out to quick.............dave...

[Wh15ky]

Thanks very much for the replies folks. Just one last question about priming though! Should you start the tiling fairly soon after priming or is it ok to prime the walls then leave them for say a week or so before getting on with the tiling.

[Fekin]

Nah, prime the morning your going to tile in the afternoon, it normally dries fairly quickly anyway, even if it's still a bit tacky, it gives your adhesive more stick.