I have customer that wants me to tile out her kitchen, all the plaster work is sound but some of the walls have been painted with emulsion which is not flaking and is in very good condition, will it be ok to treat the emulsioned walls with a coat of Bal APD primer and then tile over as normal, or do I need to remove the paint which will create a lot of work, and then tile onto the plaster surface. Thanks for any help. Moto Slug