Tiling on old black mortar/render

[goooba769]

Right then, I’m changing my bathroom and after removing the old tiles I have patches (not very deep, adhesive would more than cope filling it) down to the old black mortar/render they used to level the walls. Now it seems a bit dusty and was wondering would a coat of BAL be advisable or should I do something else?
Due to width of bathroom I’m not going to be able to skim a new surface so I just need to confirm the best way to prepare the old wall.
Thanks for any tips in advance

 

[gcol]

If you've removed patches of the skim coat, you need to re-skim those areas - tile adhesive doesn't grip too well to bonding coat.

 

[Moz]

as my mate Gcol says you cannot tile too a bad substrate , either reskim or dot an dash board it ....

 

[goooba769]

Would BAL Prime APD enable me to tile onto this render?

 

[gcol]

Nope

 

[goooba769]

cheers

 

[Moz]

as gcol says its not smooth sub