Shellac

From Academic Kids

Shellac is a secretion of the lac insect Coccus lacca, found in the forests of Assam and Thailand. Freed from wood it is called "seedlac."

Shellac is a natural polymer and is chemically similar to synthetic polymers, thus considered a natural plastic. It can be molded by heat and pressure methods, so it is classified as thermoplastic.

Missing image
Porta_retrato_shellac_NOVA_FOTO_b.jpg
A 19th century picture frame made of shellac.

It was used from mid-19th century on to produce small goods like picture frames, boxes, toilet articles, jewellery, inkwells and even dental plates.

It is soluble in alkaline solutions such as ammonia, sodium borate, sodium carbonate, and sodium hydroxide, and also in various organic solvents.

When dissolved in acetone or alcohol, shellac yields a varnish of superior gloss and hardness and is available in numerous grades. It is used in the traditional "French polish" method of finishing furniture. Orange shellac is bleached with sodium hypochlorite solution to form white shellac. Because it is compatible with most other finishes, shellac is also 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. Lightly tinted shellac preparations are also sold as paint primer.

As it is edible, shellac was used as a coating on pills or candies such as M&Ms.

Shellac was also used in the production of gramophone records until ca. 1950. See gramophone record for details.

It is now considered obsolete as a moulding compound, having very few applications.

See also:

sk:šelak nl:schellak

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