Historical In the early- and mid-twentieth century, orange shellac was used as a one-product finish (combination stain and varnish-like topcoat) on decorative wood panelling used on walls and ceilings in homes, particularly in the US. In the
American South, use of knotty
pine plank
panelling covered with orange shellac was once as common in new construction as
drywall is today. It was also often used on kitchen cabinets and hardwood floors, prior to the advent of
polyurethane. Until the advent of
vinyl, most
gramophone records were pressed from shellac compounds. From 1921 to 1928, tons of shellac were used to create 260 million records for Europe. Use of shellac for records was common until the 1950s and continued into the 1970s in some non-Western countries, as well as for some children's records. Until recent advances in technology, shellac was the only glue used in the making of
ballet dancers'
pointe shoes, to stiffen the box (toe area) to support the dancer en pointe. Many manufacturers of pointe shoes still use the traditional techniques, and many dancers use shellac to revive a softening pair of shoes. Shellac was historically used as a protective coating on paintings. Sheets of
Braille were coated with shellac to help protect them from
wear due to being read by hand. Shellac was used from the mid-nineteenth century to produce small moulded goods such as
picture frames,
boxes, toilet articles,
jewelry,
inkwells and even
dentures. Advances in
plastics have rendered shellac obsolete as a moulding compound. Shellac (both orange and white varieties) was used both in the field and laboratory to glue and stabilise dinosaur bones until about the mid-1960s. While effective at the time, the long-term negative effects of shellac (being organic in nature) on dinosaur bones and other fossils is debated, and shellac is very rarely used by professional conservators and fossil preparators today. Shellac was used for fixing
inductor,
motor,
generator and
transformer windings. It was applied directly to single-layer windings in an alcohol solution. For multi-layer windings, the whole coil was submerged in shellac solution, then drained and placed in a warm location to allow the alcohol to evaporate. The shellac locked the wire turns in place, provided extra insulation, prevented movement and vibration and reduced buzz and hum. In motors and generators it also helps transfer force generated by magnetic attraction and repulsion from the windings to the rotor or
armature. In more recent times, shellac has been replaced in these applications by synthetic resins such as
polyester resin. Some applications use shellac mixed with other natural or synthetic resins, such as
pine resin or phenol-
formaldehyde resin, of which
Bakelite is the best known, for electrical use. Mixed with other resins,
barium sulfate,
calcium carbonate,
zinc sulfide,
aluminium oxide and/or cuprous carbonate (
malachite), shellac forms a component of heat-cured capping cement used to fasten the caps or bases to the bulbs of electric lamps.
Current uses It is the central element of the traditional "
French polish" method of
finishing furniture, fine
string instruments, and
pianos. Shellac, being edible, is used as a
glazing agent on pills (see
excipient) and sweets, in the form of
pharmaceutical glaze (or, "confectioner's glaze"). Shellac is used as a 'wax' coating on citrus fruit to prolong its shelf/storage life. It is also used as a small portion of the coating that replaces 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. Shellac is an odour and stain blocker and so is often used as the base of "all-purpose" primers. Although its durability against abrasives and many common solvents is not very good, shellac provides an excellent barrier against water vapour penetration. Shellac-based primers are an effective sealant to control odours associated with fire damage. Shellac has traditionally been used as a dye for cotton and, especially, silk cloth in Thailand, particularly in the north-eastern region. It yields a range of warm colours from pale yellow through to dark orange-reds and dark ochre. Naturally dyed silk cloth, including that using shellac, is widely available in the rural northeast, especially in
Ban Khwao District,
Chaiyaphum province. The Thai name for the insect and the substance is "khrang" (Thai: ครั่ง).
Wood finish Wood finishing is one of the most traditional and still popular uses of shellac mixed with solvents or alcohol. This dissolved shellac liquid, applied to a piece of wood, is an evaporative finish: the alcohol of the shellac mixture evaporates, leaving behind a protective film. Shellac as wood finish is natural and non-toxic in its pure form. A finish made of shellac is UV-resistant. For water-resistance and durability, it does not keep up with synthetic finishing products. 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.
Other Shellac is used: • in the tying of artificial flies for trout and salmon, where the shellac was used to seal all trimmed materials at the head of the fly. • in combination with wax for preserving and imparting a shine to
citrusfruits, such as
lemons and
oranges. • in
dental technology, where it is occasionally used in the production of custom impression trays and temporary denture baseplate production. • as a binder in
India ink. • for
bicycles, as a protective and decorative coating for
bicycle handlebar tape, and as a hard-drying adhesive for
tubular tyres, particularly for
track racing. • for re-attaching ink sacs when restoring vintage
fountain pens, the orange variety preferably. • applied as a coating with either a standard or modified Huon-Stuehrer nozzle, can be economically micro-sprayed onto various smooth candies, such as chocolate coated peanuts. Irregularities on the surface of the product being sprayed may result in the formation of unsightly aggregates ("lac-aggs") which precludes the use of this technique on foods such as walnuts or raisins. • for fixing pads to the key-cups of
woodwind instruments. • to stiffen and impart water-resistance to felt hats, as a constituent of
gossamer (or
goss for short), a cheesecloth fabric coated in shellac and
ammonia solution used in the shell of traditional silk
top and riding hats. • for mounting insects, in the form of a gel adhesive mixture composed of 75% ethyl alcohol. • as a binder in the fabrication of
abrasive wheels, imparting flexibility and smoothness not found in vitrified (ceramic bond) wheels. 'Elastic' bonded wheels typically contain
plaster of paris, yielding a stronger bond when mixed with shellac; the mixture of dry plaster powder, abrasive (e.g.
corundum/
aluminium oxide ), and shellac are heated and the mixture pressed in a mould. • in
pyrotechnic compositions as a low-temperature fuel and binder, where the high ratio of hydrogen prevents creation of carbon particles even during low oxygen combustion and produces relatively high temperature combustion. • in
jewellery; shellac is often applied to the top of a 'shellac stick' in order to hold small, complex, objects. By melting the shellac, the jeweller can press the object (such as a stone setting mount) into it. The shellac, once cool, can firmly hold the object, allowing it to be manipulated with tools. • in
watchmaking, due to its low melting temperature (about ), shellac is used in most mechanical movements to adjust and adhere pallet stones to the
pallet fork and secure the roller jewel to the roller table of the
balance wheel. Also for securing small parts to a 'wax chuck' (faceplate) in a watchmakers' lathe. • in the early twentieth century, it was used to protect some military
rifle stocks. • in
Jelly Belly jelly beans, in combination with
beeswax to give them their final buff and polish. • in modern traditional
archery, shellac is one of the
hot-melt glue/resin products used to attach
arrowheads to wooden or bamboo
arrow shafts. • in alcohol solution as
sanding sealer, widely sold to seal sanded surfaces, typically wooden surfaces before a final coat of a more durable finish. Similar to French polish but more dilute. • as a topcoat in
nail polish (although not all
nail polish sold as "shellac" contains shellac, and some
nail polish not labelled in this way does). • in sculpture, to seal
plaster and in conjunction with wax or oil-soaps, to act as a barrier during mold-making processes. • as a dilute solution in the sealing of
harpsichord soundboards, protecting them from dust and buffering humidity changes while maintaining a bare-wood appearance. • as a waterproofing agent for leather (e.g., for the soles of
figure skate boots). • as a way for ballet dancers to harden their
pointe shoes, making them last longer. == Gallery ==