Shellac
Shellac is an amber coloured resin, produced by refining the secretions of the lac insect.1 Lac (Laccifera lacca) are small scale insects which exist naturally in the deciduous forests of Southeast Asia. 1 However, their cultivation on farmed trees is common practice in many countries, including India, Thailand, China, Indonesia and Vietnam.1
How is Shellac Produced?
Farmed host trees are pruned to encourage growth of new shoots, which are rich in sap and will provide food for the lac.2 Once the young shoots are established, the trees are then ‘inoculated’ with lac in a process where branches containing egg laying females, referred to as ‘broodlac’, are put into the prepared trees.3
Female lac lay up to 100 eggs each and these hatch into larvae which break out of the broodlac and settle closely on to the fresh shoots of their host tree.3 Here they use their long proboscis to feed upon the sap within the twigs.4 As they feed, the larvae begin to secrete lac resin, forming a protective cocoon around themselves 3 and it is within this cocoon that they develop into adults.4 As the young lac grow, so do their cocoons and the lac resin coalesces between individuals to form one body, covering the entire swarm.5
The males emerge from within the body of resin to complete their six month lifecycle.4 They walk across the surface of the joined cocoons and fertilise the females within.4 The males die shortly after mating.4
Once the female lac have been fertilised, the trees are then harvested.2 This involves the removal of any occupied twigs or branches with the attached resin.2 A proportion of the new generation of broodlac will be set aside to inoculate more host trees, while the rest will be processed in to shellac.4
The twigs are scraped by hand to remove the layer of encrusted resin.3 At this stage, the raw lac material is known as sticklac.3 The sticklac is ground and sieved to remove any debris before being washed to get rid of the lac dye, a red pigment that comes directly from the insects crushed bodies.1 Lac dye may be discarded in the production of shellac, however if lac dye is the intended primary product then the lac resin is harvested before the males have emerged from their cocoons and the sticklac is dried in the sun to kill the lac beetles.2
Once the sticklac has been washed it is then dried, separated and sieved again, to create a partially refined product known as seedlac.5 Seedlac is further refined through a process of heating and filtering before being stretched to produce large brittle sheets of shellac which are then broken into small flakes.3
Uses of Shellac
Lac dye is primarily used to dye leather, silk and wool,2 however it is also used as a colouring in some foods and soft drinks 1 and as a traditional cosmetic in India.2
Shellac is used in the pharmaceutical industry as a coating for some tablets;6 in household products such as sealing wax, adhesives, polish and varnish;1 in cosmetics such as hairspray,7 perfume and lipstick;6 in food products as a glaze on confectionary, 1 fruit and coffee beans;7 as a binding agent in printing inks and paints;7 and in agriculture, coating urea to produce a slow releasing fertiliser. 1
When used in food, shellac has the food additive E number E904.
Statistics
- Approximately 300,000 lac insects are killed to produce 1kg of lac.5
- Lac is made up of 25% insect debris.3
- Annual production of lac is estimated at 20,000 tonnes globally.1
- India and Thailand are the main producers of lac, together generating 85% of the global yield.1
- India has 181 lac processing centres.8
- The main importers of lac products are Egypt, Germany, Indonesia, Italy and USA.1
References
- Food and Agriculture Organisation of the United Nations. International trade in non-wood forest products: An overview http://www.fao.org/docrep/x5326e/x5326e0c.htm (accessed 28th September 2010)
- Food and Agriculture Organisation of the United Nations. Non-wood forest products 4 http://www.fao.org/docrep/v8879e/V8879e08.htm (accessed 28th September 2010)
- Shellac Export Promotion Council. Frequently asked questions http://www.shellacepc.com/faq.html (accessed 28th September 2010)
- Artisans of the Valley. Shellac http://www.artisansofthevalley.com/ed_shellac.shtml (accessed 28th September 2010)
- Antique Conservation. Shellac http://www.antcons.com.au/Shellac.html (accessed 28th September 2010)
- Shellac Export Promotion Council. History of shellac http://www.shellacepc.com/history.html (accessed 28th September 2010)
- Lexportex (India) PVT. Ltd. Uses of shellac http://www.indianshellac.com/uses.html (accessed 4th October 2010)
- Indian Institute of Natural Resins and Gums. Lac statistics at a glance 2010 http://ilri.ernet.in/~iinrg/Lac%20statistics%202010.pdf (accessed 29th September 2010)