Industry News

Shellac Application Process

Shellac Application Process


The sticklac (raw Shellac) was crushed and washed frequently to remove the bug bodies and a portion of the coloring matter. After drying the washed sticklac, we get the commercial variety of Seedlac. It contains around 3~5% impurity. Seedlac is mostly used for conversion into variety of Shellac including Bleached Shellacc, Dewaxed Shellac and Decolorized Shellac, etc.


There are two methods to extract Shellac flakes. One is hot-filtering method and the other is solvent method. The so called hot-filtering method is using hot-filtering kettle to heat the Seedlac to melting state , then filter the impurities and press the molten Seedlac into flakes. High pressure and temperature are involved in the process, thus the viscosity of the finished Shellac is lowered and the thermal life is shortened. As the name suggests, the solvent method is using suitable solvents (usually industrial alcohol) to dissolve the Seedlac, then filtering or centrifuging it to remove impurities. And then use vacuum distillation to get the dry Seedlac and pressed it into flakes. High pressure and temperature are not applied during the process, so the nature of the Seedlac is remained.


We supplies Seedlac and Shellac flakes in variety of dewaxed Shellac, decolorized Shellac, dewaxed decolorized Shellac (table 1) and bleached Shellac (table 2).

Grade I II I II I II
Color, max 18 2 5 2 3
Matter Insoluble In Hot Alcohol (%), max 0.2 0.4 0.5 0.5 0.2 0.4
Waxiness (%), max 0.2 0.2 5.5 5.5 0.2 0.2
Heat-hardening time (170+-0.5℃), min 2.0 2.0
Softening point (℃) 72
Moisture (%) 2.0 2.0 2.0
Matter Soluble in Water (%) 0.5 0.5 0.5
Ash (%) 0.3 0.3 0.3
Rosin & Orpiment N/A N/A N/A

Table 1.

Grade I II I II
Color, max 1.5 2.0 1.0 2.5
Matter Insoluble In Hot Alcohol (%), max 1.0 2.0 0.1 0.2
Moisture (%), max 3 3 3 3
Waxiness (%), max 5.5 5.5 0.1 0.2
Chlorinity (%), max 2.0 3.0 1.5 2.0
Heat-hardening time(170+-0.5℃), min 60 30 120 90
Ash (%), max 1.0 1.5 0.5 1.0
Matter Soluble in Water (%), max 1.0 1.0 0.5 0.5
Acid (mg/g) 75~90 75~90
Pb (mg/g), max 5
As (mg/g), max 1
Rosin & Orpiment N/A N/A

Table 2.


Wood Finish. Shellac is used as a barrier or primer coat on wood to prevent the bleeding of resin or pigments into the final finish, or to prevent wood stain from blotching. Shellac varnish is simple and convenience for use. With the features of strong force of adhesion, dry rapidly, smoothly coating, full of elasticity, uniform luster, it is widely used in the wooden ware industry. Instead of using methanol lacquer, Shellac varnish is applied more frequently in exclusive furniture in recent years, because the methanol lacquer is toxic to human beings. And Shellac is the central element of the traditional “French polish” method of finishing furniture and fine viols, guitars and pianos.

Fruit Waxing. Shellac is edible and it is used as coating agent for fruit to extend the shelf life, and also used as a glazing agent on pills and candies. Because of its alkaline properties, Shellac-coated pills may be used for a timed enteric or colonic release. It is also used to replace the natural wax of the apple, which is removed during the cleaning process.

Leather Protection. Shellac is used as polish and protective coating agent in the leather industry.

Military Industry. Shellac is used in the military industry mainly as a finishing agent, insulation material and blocker for mixed gunpowder. And it is also used to produce UV –proof and radiation-proof military materials.

Electrical Industry. Shellac is used in producing insulating cardboard and micanite, grinding electrical insulator, and also used in the insulating varnish, bulb, daylight lamp and electric tube cement.

Rubber Industry. Shellac is mainly used as the surface coating and bulking agent of rubber products, so as to enhance the abrasion-resistance, oil-resistance, acid-resistance, waterproof and insulativity. It can slow down the aging rate, extend expire date and improve the physic and mechanical properties like tension stress and tear resistance of rubber as well.

Paper Sizing. Shellac is used to produce insulating paper,dunnage paper. Shellac also used as a decorative and protective finish in coated paper, food wrapper and lampshade paper, etc.

Others. Shellac could be used to produce small molded goods like picture frames, boxes, toilet articles, jewelry, inkwells and even dentures. It is used by many cyclists as a protective and decorative coating for their handlebar tape. Shellac is used as a hard-drying adhesive for tubular cycle tires, particularly for track racing. Sheets of Braille were coated with Shellac to help protect them from wear due to being read by hand. And Shellac is used as a binder in India ink. It was historically used as a protective coating on paintings. It is an odor and stain blocker, and can provides an excellent barrier against water vapor penetration. Shellac-based primers are an effective sealant to control odors associated with fire damage. Shellac finds a use in pyrotechnic compositions as a low-temperature fuel, where it allows the creation of pure ‘greens’ and ‘blues’, colors difficult to achieve with other fuel mixes in fireworks formulae.