Petting is gently stroking the
metalic or clay with your fingertip to get the mica bits to lie in such a
way that they are shinier. I think it convinces them to lie shiney sides up.

Right! known as "mica shift", manipulating the mica catching the light makes
several cool effects possible. You can also pet the matte colored clays tho
just for smoothness----makes sanding or buffing either easier, or not needed at
all.
Sarajane

Sarajane's Polymer Clay Gallery
http://www.polyclay.com