Sodium Silicate
Interested in pottery surfaces? Try this sodium silicate pottery technique!
Brushing the surface of a thrown pot with sodium silicate, quick-drying the surface with a heat gun or blowtorch until the surface no longer is tacky, then expanding the form from inside can give a piece of pottery an aura of instant antiquity.
The sodium silicate is a thick liquid salt solution that forms a thin skin that, with applied heat, quickly hardens on the surface, encasing the soft and therefore, still malleable, clay cylinder beneath. Normally used as a deflocculant for casting slips, in this use it is quickly dried to the touch with some heat from a blowtorch. At this point, it is like a candy apple, crunchy on the outside and soft inside.