Matthew asks for a definition of 'Thin Tosh' for all you non-British
English speaking people.  This is just a common term used in Great
Britain for the thin rubber cloth used in covering playing pneumatics,
i.e., the thinnest rubber cloth used.  I do not know its etymology.

The term Tosh doesn't appear to be used for any other thickness of
rubber cloth and it is sometimes used just on its own, Tosh, to mean
the same thing.

Best wishes from GB,
Nicholas Simons