I have a Roberts DAB radio with a traditional style case It seems to be
covered in some fake leather or suede effect stuff with a very thin
plastic skin on some powdery cork-like substance.

The plastic is shedding, it's really badly made. I thought I might get
a second hand faulty one on eBay and swap the innards, but they all seem
to have the same problem.

I can fairly easily remove the plastic coating, but how could I seal the
crumbly substrate?

Cheers
--
Clive