John Rumm coughed up some electrons that declared:

Bruce wrote:
Tim S wrote:
Just peeled some more old flooring up in the bungalow. It had been stuck
down with what looks like industrial evo-stick. The flooring cleaved off
with a spade, but there remains a layer a mm or two thick of the rubbery
adhesive.

snip

Has anyone any bad experiences of tiling straight over this sort of
stuff?


Yes, I went over it with a levelling screed, which gave me a smooth and
level surface to tile on to.

A shop fitters trick for killing off the stickyness of surfaces like
this is to sweep some dry levelling compound powder over it. It sets
into all the sticky bits and stabilises them.



Ah. I seem to have already achieved that with plaster dust

It was only the technical bloke from Mapei who said "scrape it off" that
made me think - but then, I suppose he'd have to say that.

The first Mapei bloke was a bit more helpful, in that he said (of sticking
Marmox to concrete with no DPM): "well, we can't guarantee it won't fall of
in 20-30 years due to hyrdostatic pressure - but KeraQuick's your best bet
of all our products". Simple advice with pros and cons - then I can make an
informed decision.

Cheers

Tim