Another Travertine question

[marktiling]

I have 65m2 of Travertine to lay onto wet UFH covered by a latex screed (already laid).
I was going to lay C1 matting onto this, then the tiles.
My question is -
I like using Ardex adhesive and know I need white but any recommendations which is the best for
1) between the screed and the matting
2) between the matting and the Travertine
I have a quote to do and Ardex helpline is shut !

Or can anyone recommend something else they have used - I have searched this forum for quite a while and seem to be getting more confused.
Thanks everyone.

 

[DHTiling]

onto wet UFH covered by a latex screed (already laid).

Can you define latex screed please..?

 

[Daz]

Assuming that the floor screed has been smoothed with a flexible slc, then you have the option of Ardex S16 with E90 additive or, my personal choice, Ardex X7R. Obviously, you can use grey to fix the decoupler then white for the trav.

Alternatively, you could consider Mapei Keraquick (grey & white).

As Dave requested, can you confirm the floor condition / make up first please?