Shellac

Shellac (CAS 9000-59-3), also known as lac resin and designated E904, is a natural resinous secretion refined as a film-forming and surface-finishing agent.

Where is Shellac used?

• Food: E904 glazing agent on confectionery and fresh produce
• Pharmaceutical tablets: protective, high-gloss finish that extends shelf life
• Coatings and printing: wood lacquers, ink binders, overprint varnishes
• Leather finishing builds durable, flexible surface films that resist scuffing.
• Paper and packaging: moisture-barrier coating and adhesive component for labels, seals, specialty paper treatments
• Electrical insulation due to dielectric properties.
• Coated pills for timed enteric or colonic release due to resistance to stomach acids.
• Shellac bond (E-bond) in precision grinding wheels, hot-press molded with abrasive grain and cured over several days.

Good to know: Dewaxed bleached shellac is preferred for food and pharmaceutical use. Food-grade material conforms to E904 specifications; pharmaceutical-grade meets USP or BP standards.

Formulation notes

• Coating weight about 25–40 g/m².
• Low-flow shellac in abrasive bonding produces density gradients and incomplete bridging; high-flow grade required for uniform flow.
• Heat refining keeps natural wax (around 5%) and amber color; solvent refining removes wax to 0.2% or lower; bleaching removes color oxidatively.

Typical specification

• Dewaxed shellac produced by solvent refining to reduce wax to 0.2% or lower.
• Lemon #1 flake and high-flow Lemon #1 shellac both have a wax content of 2.5–5%.
• Dewaxed shellac grade DM has a maximum colour of 8 Gardner in 20% ethanol.
• Dewaxed shellac grades have an acid number of 65–80 per DAB 9.
• Dewaxed shellac grades have a maximum wax content of 0.2% per USP XXIII.

Storage, packaging and handling

• Dry flake stored cool and dark keeps for years.

Frequently asked questions about Shellac

What color grades of shellac are available?

Shellac comes in many warm colors ranging from very light yellow ("platina") to very dark brown ("garnet"), with many brown, yellow, orange, and red varieties in between.

What are the solubility characteristics of shellac?

Shellac is soluble in alkaline solutions of ammonia, sodium borate, sodium carbonate, and sodium hydroxide, as well as in various organic solvents.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.