Hello all,  Thanks for all the responses.  This is just an interesting
topic.  So far we seem to agree that the Acrylic medium changes the
leather the most.  I will have to try and get some of that silicone
grease, after all, to see the effect.

I have sealed pouches in my personal Duo-Art some ten years ago with
silicone sealer very much thinned down.  It still plays fine but I have
never opened it since to see what has happened to the pouch stiffness.
It repeats fine, though, on soft passages.

Regards,

Bernt Damm
Cape Town