Priming floor for tile over tile

[aflemi]

Tiling over 30-40 year old ceramic tiles stuck hard to solid floor bed. Was planning to roughen, clean with sugarsoap, prime with sbr then tile over. No ufh.
Tile Giant salesman recommended just cleaning then use Mapei ecoprim, excellent adhesive properties for this job.
Sounds good to me, anyone have an opinion to the contrary?

 

[peteablard]

Never used it myself but have heard good reports on here about ecoprim

 

[Gazzer]

Ecoprim or ecoprim grip ?

 

[bugs183]

Ecoprim grip is the stuff, it's great.

 

[On one]

Used Ecoprim grip for the first time last year,very easy to apply and when spreading adhesive onto it I was surprised how much confidence I had in it. But if the original tiles are not securely fixed..........