Sticklac, edible, is a hard amorphous natural resin & considered GRAS (Generally Recognized As Safe) by the FDA (Food and Drug Administration). The increasing use of the properties of lac has not been the result of chance. Alkyl esters of shellac in combination with cellulose nitrate and various synthetic resins make excellent resin-plasticizers for lacquers. On heat polymerization, the alkyl esters change into tough, flexible products possessing rubber-like properties. Aleuritic acid esters compounded with cellulose ethers and esters lend themselves excellently for the preparation of lacquers, plastics and fibre. Lac was employed as a dye in cosmetics and as as constituent of medicines for centuries. To-day lac is being used in many industries as a film former, a plastic, an insulator and an adhesive and cement.
Sticklac is used in Electrical equipments because of its excellent dielectric properties, dielectric strength, low thermal conductivity and a low coefficient of expansion. Shellac coatings do not change their electrical properties under UV-radiation.
Because of its acidic properties (resisting stomach acids), shellac-coated pills may be used for a timed enteric or colonic release. Shellac is used as a ‘wax’ coating on citrus fruit to prolong its shelf/storage life. It is also used to replace the natural wax of the apple, which is removed during the cleaning process. When used for this purpose, it has the food additive E number E904.
It is the central element of the traditional method of finishing furniture and fine violas, guitars and pianos. 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. Shellac is an odour and stain blocker and so is often used as the base of “solves all problems” primers. Lac provides an excellent barrier against water vapour penetration. Shellac-based primers are an effective sealant to control odours associated with fire damage.
