Hi Norm
That's interesting.
You use to see this effect on old typewriters too.
It is sometimes called 'Wrinkle' paint or 'Crinkle' paint.

BB will be much better at understanding this than me:-
https://www.autobarn.com.au/vht-wrinkle-finish-black-sp201
http://www.frost.co.uk/how-to-use-vht-wrinkle-finish-paint
http://www.build-threads.com/general-car-stuff/diyhow-to-wrinkle-texture-paint/


Cheers
-----------------
Jack