Shellac is a natural, non-toxic resin secreted on the barks of trees by the female lac insect (Kerria lacca). Raw shellac can be collected, processed and sold as dry flakes, which can then be dissolved in a solvent to make liquid shellac. Shellac comes in many colors and its color is influenced by the sap of the tree the lac insect is living on, as well as the time of harvest. Raw, unprocessed shellac is normally orange to brown in color.
Raw shellac is a mixture of many molecules and can be separated into three main components: (1) hard resin; (2) soft resin; and (3) wax. Raw shellac can be processed to remove the wax and can also be bleached. Traditional bleaching techniques fail to produce shellac that is truly colorless or more de-colored, and a significant amount of color remains. Some manufacturers market their bleached shellac as “white”, but a closer examination of their product reveals that it is in fact pale yellow and not purely white. The presence of this residual color in the shellac resin is unsuitable for a number of applications in which clear and colorless or more de-colored shellac is desired, or the presence of residual color would be aesthetically or cosmetically unappealing.
One industry which would welcome colorless shellac or a more de-colored product is the dental industry. Dental decay affects the majority of the population and poses a serious and sometimes expensive problem, particularly for young children. A shellac-based dental coating product would be welcomed, yet the presence of residual color in the shellac resin renders such a product cosmetically unappealing for certain cultures where, for example, whiter teeth is considered attractive. Furthermore, more durable shellac-based dental coating products, which can withstand regular abuse such as eating, drinking and brushing, would also be desirable.
Another industry which would welcome colorless shellac or a more de-colored product is the food and drug industry. Shellac is edible and it is used as a glazing agent on pills and candies in the form of pharmaceutical glaze (or confectioner's glaze). Shellac is also suitable as a food coating, and has been used to replace the natural wax of apples, which is removed during the cleaning process. A colorless or a more de-colored shellac product may be more aesthetically appealing. Other industries would also welcome colorless or more de-colored shellac products. For example, shellac is an odor and stain blocker and can be used as a primer for a variety of surfaces to provide, for example, a barrier against water. Shellac is also used in nail varnishes and nail polishes, and colorless or more de-colored shellac may be desirable in such products.
The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.