Formulating Black Enamels with Gilsonite

Gilsonite has a long history in black enamels and “japan” finishes for metal parts.

Basic formulation

• Gilsonite: 15–30% of binder
• Drying oil or alkyd resin
• Solvent (aromatic or aliphatic)
• Driers
• Optional carbon black

Properties achieved

• Hard, glossy black film
• Good chemical resistance
• Fast drying with heat-curing options

Applications

Machinery, agricultural equipment, castings and hardware.

Air-dry vs. baking enamels

• Air-dry enamels use drying oils or alkyds with metal driers. Gilsonite adds hardness and speeds dry-to-touch.
• Baking (stoving) enamels are cured at elevated temperature, producing very hard, chemically resistant films – the classic “black japan” finish.

Example starting formulation (air-dry)

Quality checks

Gloss, hardness, drying time, adhesion and resistance to water and mild chemicals.

See paint grade gilsonite and solvent guide.