Gilder’s burnish clay or clay bole is an essential part of the traditional water gilding system with gold and silver leaf. Brushed in multiple thin coats over a primed or gesso surface, burnish clay is what allows water gilded gold or silver to be polished to a mirror gloss finish. Selhamin burnish clay is available in dry cone form which needs to be crushed, reconstituted with water into a slurry and screened before being mixed with a prepared adhesive (such as rabbit skin glue). Selhamin clay is also available in a prepared paste in which the preliminary reconstituting has already been done. A loose of rule of thumb formula for using the Selhamin prepared paste is as follows.
Selhamin premixed clay – approx. 60%
Prepared rabbit skin glue solution – approx. 2.5 – 3%
Additional water - approx. 37%
Selhamin burnish clay is available in a range of traditional oxide/earth colors to compliment the various shades or alloys of gold and silver leaf. It should be noted that silver can be affected by minerals in the burnishing clays and the Selhamin blue clays have been especially formulated to avoid this.
Selhamin Burnishing Clays are available in both the dry cone and premixed (wet) forms.