Terry
Sorry, you are right that "fine" is rather ambiguous.
The point is to try to use Perlite/Vermiculite grains that are smaller
than the Pinguicula leaves you are using to propogate from. Otherwise
you can easily end up with the leaves falling between the grains which
they don't usually like this. If people cannot get such a small grain
size of Perlite or Vermiculite, simply use the smallest you can find and
be a bit more careful on laying out the leaves.
Regards
Paul