Shellac is a resin secreted by the female lac bug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes, which are dissolved in denatured alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. Shellac functions as a tough all-natural primer, sanding sealant, tannin-blocker, odor-blocker, stain, and high-gloss varnish. Shellac is often the only historically appropriate finish for early 20th-century hardwood floors, and wooden wall and ceiling paneling. From the time it replaced oil and wax finishes in the 19th century, shellac was the dominant wood finish in the western world until it was replaced by nitrocellulose lacquer in the 1920s and 1930s. Shellac was used from mid-19th century to produce small moulded goods like picture frames, boxes, toilet articles, jewelry, inkwells and even dentures. Although advancement in plastics have rendered shellac obsolete as a moulding compound, it remains popular for a number of other uses. In dental technology, it is still occasionally used in the production of custom impression trays and (partial) denture production. Shellac is used by many cyclists as a protective and decorative coating for their handlebar tape. Shellac is used as a hard-drying adhesive for tubular cycle tires, particularly for track racing. Orange shellac is also the preferred adhesive for reattaching ink sacs when restoring vintage fountain pens. It has always been the preferred hot-melt adhesive for fixing leather saxophone pads into their metal key-cups. Shellac is used as a binder in India ink. Shellac is edible and it is used as a glazing agent on pills and candies in the form of pharmaceutical glaze. 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.