Aaron Newman, age 13. of Casper, Wyo., for his question:
WHERE DO WE GET LAC?
Lac is a sticky substance given off by scale insects. They gather by the hundreds of thousands on the twigs and branches of the soapberry and acacia trees of India and Burma. The sticky material these insects secrete is called lac. The shellac that protects furniture and floors is made from lac.
The word lac comes from the Persian word "lak" and the Hindu word "lakh," both of which mean hundred thousand.
Lac insects are tiny and scaly, with wings that fold back along their bodies. They pierce the bark of trees with their long beaks and feed on the sap.
As the insects feed on the sap, they discharge a quantity of lac to protect themselves from their enemies. The female insect lays several hundred eggs before she dies.
The young insects hatch out of the eggs as wormlike larvae. When the larvae grow into insects, they look for new, fresh twigs to feed on. This period of their life cycle is called swarming.
Lac is usually harvested by cutting almost all of the twigs before the larvae mature. Workers leave some larvae to provide future generations of insects.
When the larvae are ready to swarm, the twigs are fastened onto trees where the workers want the insects to feed.
The crude material gathered from the twigs is called stick lac. Workers grind it between stones and wash it in water to remove the coloring matter. In this stage, the substance is called seed lac.
Workers melt seed lac in long, narrow cloth bags and squeeze it through the cloth to filter out impurities. Then they take the warm lack between their teeth, toes and fingers and stretch it into thin sheets. When these sheets cool, they are broken into flakes.
The orange colored shellac we buy in a store is made from the resin flakes obtained from sheets of broken lac and dissolved in alcohol. Lac may also be bleached and sold as white shellac.
Lac often is formed into cakes called button lac.
Shellac may be molded into electric insulators and other articles. It also is used in abrasives, sealing wax and some phonograph records.
Shellac is used much as a varnish is used. When shellac is applied to a surface, the alcohol in the solution evaporates, leaving only a hard, shiny finish.
Natural resins have largely been replaced today by synthetic resins.
Resins in general form a class of vegetable substances that are used in varnishes, medicines and soaps. Natural resins may be divided into three main groups: those that flow from plants as a result of wounds, those extracted from wood by solvents, and fossil resins found with the preserved remains of animals and plants.
In a separate class is the resin we call lac.