Acronym and details:    excretion of tropical beetle mixed with fillers such as cotton flock, powdered slate, wood flour

Group:   thermoplastic or set depending on heat used in manufacture

Developed:   known for thousand of years; used to make products from 1860s to 1940s

Trade names:   Diatite; Florence compound; Peck

Manufacturing process:   compression moulding

Cost:   medium

Colour:   dark brown, blackand occasionally paler dull shades

Transparency:   always opaque

Rigidity:   rigid

Feel:   hard

Smell:   sealing wax

Other:   brittle; capable of reproducing very fine detail

Typical uses:   cases for daguerreotypes and ambrotypes (early forms ofphotographs on glass); dressing table sets; 78 rpm records until 1948; as stiffening for bowler and riding hats; also used as lacquer

Degradation:   relatively stable