Shellac & Lac Based Products

Serving-with-shellac

History of Shellac | From Lac to Shellac | Properties of Shellac | Applications of Shellac 

HISTORY OF SHELLAC

Atharva Veda, wisdom of ancient truth-seers of India, is estimated to be several  thousand years old. It clearly says that both lac aswell as lac dye served as effective & valuable medicine.

The Veda reports that an extract of lac made with water, which contains mainly lac dye or laccaic acid, was widely used on open wounds for quick healing and tissue regeneration. Use of lac in joining up of broken bones was also common.

The Veda finally indicates a slurry of lac paste in water (which would mainly contain lac dye) mixed with ghee (butter oil) and milk which was commonly partaken orally by sick or wounded persons to get back health.

The manuscript indicates that lac dye is not only safe enough to be used on open   wounds but was also to be taken orally quite often to recoup health and vigour.

The Atharva Veda bears the title ‘Laksha’ and gives a brief account of lac, the lac insect, the medicinal use of lac and a prayer chum addressed to the female lac insect personified as a beautiful young maiden. It is interesting to note that even in those early days, a fairly accurate knowledge of the biology of lac insect was available.

“Tzu K’wang (Lac) is red like Sue Kie (Dragon’s  blood) but differs in that itexudes  from the leaves of a tree, and is generated through insects. Lac is the produce of Nan-Fan (Indo-China). It is dark-red-brown in colour, with the texture resembling an ore, hence the name “dark-red-brown ore’. It is also collected attached to branches, and called ‘red-brown twig’. One writer says that the lac tree grows in Chen La Kuo (the country of genuine wax) or Cambodia, where it is locally called Le-Ka or Lo-Ka. He also reports that ants carry soil up to the extremity of branches and build there a nest on trees. This soil, carried by ants, wetted by rain and dew, hardens and becomes lac.

Another writer, however, says that when mist, dew and rain moisten the branches, lac is formed by a tiny insect, like an ant or a louse which creeps on the branches of trees, like the insect which produces Chinese wax on the Wintergreen tree. Hence the tree is artificially propagated from cuttings.  At present, lac is used in South West China for making rouge. It is also ground up and used for dyeing silk scarlet red; such a cloth is called Yi C’hi C’hih Hsu, literally, ‘ant-gum red cloth’. A granular lac is left as a waste product and is utilised by jade workers”. -  (Chinese Herbal, Li Shih-Chen. 1582 A.D.)


Stick lacMost people have no idea of what Shellac is or where it comes from. Shellac is a natural, organic resin that comes from an insect, Laccifer Lacca, that is about the size of an apple seed. This bug alights on certain trees indigenous to India and Thailand and during its reproductive cycle feeds on the sap that it sucks from the twigs of these trees. The bug secretes an amber coloured resinous substance that is called ‘lac’, a word that comes from the Sanskrit word ‘lakh’ which means one hundred thousand. The resin forms cocoon around the insect which serves to incubate the eggs she lays. This cocoon is the raw material from the Shellac and is called ‘sticklac’, because it contains resin, parts of the twig and bug remains. The stick lac is washed and then refined either chemically or by hand, to produce the raw material available for sale.

The original cultivation of Shellac is for the resin, or rather, for the dye that gives the resin its characteristic colour. The use of the lac dye can be traced back to 250 AD when it was mentioned by Claudius Aelianus, a Roman writer on natural history. The lac dyes were removed by the initial washing of the shellac resin in large kettles, which is also the fast step in the preparing the resin. This dye remained a valuable commodity until the need – 1800′s, when Perkins an English Chemist synthesized the first chemical ‘Aniline’ dyes which killed the natural dye industry. Fortunately the use of the resin had been firmly established, so the loss of the use of the dye had little impact on shellac trade. The fast use of shellac as a protective coating appears as early as 1590 in a work by an English writer who was sent to India to observe the country and its people.

Commenting on a  procedure for applying  lac  to  wood  still  on  the lathe  he writes “they take a piece of the lac of what colour they will, and as they turn it when commeth to his fashion they spread the lac upon the whole piece of wood which  presently, with the head of the turning (melteth the waxe) so that it enter into the crests and cleaveth unto it, about the thickness of a mans nail : then they burnish it (over) with a broad straw or dry rushes so (cunningly) that all the wood is covered with all, and its hineth like glass, most pleasant to behold, and continueth as long as the wood being well looked unto. In this sort they covered all kinds of household stuffe in India”.
*From Shellac; its production, manufacture, chemistry, analyses, commerce and uses.”  - London, Sir I Pitman & Sons, Ltd.

The use of the Shellac as a furniture finish never caught on in the west until the early 1800′s and it eventually replaced wax and oil finishes. It remained the most widely used finish for wood until the 1920′s and 30′s when it was replaced by nitrocellulose lacquer.


Historical Vignettes
  • Verse 5 of the 5th volume of the ancient Hindu scriptures, the Atharva Veda (1500 – 1200 BC) is titled Laksha and gives a brief account of the lac insect and the medicinal properties of lac
  • In the same source, mention is made of a decoction, lakshadi tail, or ‘lac oil’, said to be effective in curing chronic fevers and rheumatism.
  • Perhaps one of the most infamous references to lac is of the lakshagriha (house of lac), in the ancient Indian epic, the Mahabharata (1300 BC). An inflammable mansion, cunningly constructed for the Kaurava brothers at Vanrvrataby the architect Purochak; it had the sole purpose of vanquishing their adversaries, the Pandava siblingsby burning them down, when the latter retired to the house after celebrations. The highly inflammable and mouldable property of lac was utilized in this particular instance!! (The conspiracy failed, as the Pandava brothers were forewarned about the plot).
  • Panini (550 B.C) mentioned the medicinal properties of lac in his book, the Ashtdhyayi.
  • It is known from Herodotus that the explorer, Scylax, was sent by the Persian king, Darius I (in about 515 BC), to explore the course of the Indus River. In his writings, the Periplus, Scylax was the first western explorer to describe ancient India, wherein, mention was made of lakhos chromatinos or lac dye.
  • The ancient Vinaya Pitaka texts of Buddhism contain details about the method of extraction and application of lac dye. In fact, lac dye was treasured much more than lac resin, in ancient times.
  • Pliny’s Natural History (77 AD) refers to electrone (ber) trees, which decked the Hypobus (Ganges) river in the Indian sub – continent.
  • The Wu Lu, written by the Chinese historian, Chang Po (320 AD) stated that in northern China (Chiu-Chen), there was a district called I-Fung, where “ants” crawled upon trees to produce lac (Ch’i).
  • An 8th century AD specimen of lac (Shi-Ko) is still preserved in the Shoso-In (Imperial Warehouse) at Nara, Japan.
  • In 1563, the Portuguese traveller, Garcia de Orta, described the uses of lac resin and lac dye in India.
  • The Ain-i-Akbari of Abu Fazal (1590) gives detailed procedures for the use of lac varnishes on door screens of public buildings during the Mughal rule in India
  • It is said that the Mughal emperor, Akbar, had a sweetmeat box exquisitely lacquered with lac and set with jewels, which he would keep with himself, while holding court. It had two chambers: one holding ordinary sweetmeats and the other, poisoned ones. The accused would be asked to choose from either one, and thus decide his own fate.
  • Linschoten, another Portuguese traveler (1596) reported lac cultivation in India and Burma.
  • Tavernier recorded in 1676 that lac dye was used for calico printing and lac resin was used for sealing waxes and polishes in India. In the sixteenth century, the use of lac in sealing compositions was introduced in Europe, by Spanish merchants who carried on overseas trade with India. This practically “sealed” the fate of lac resin for the preparation of sealing waxes, for which it is popular even today, although presently, few formulations of sealing wax actually contain the lac resin per se.
  • Father Tachard (1709), a Jesuit priest stationed in India, first reported that a kind of “ant” on the branches of certain of certain Indian trees, left behind a secretion, which hardened on exposure to air and sun. However, James Kerr (1781) first described the Indian lac insect scientifically.
  • In 1895, Emil Berliner, a German immigrant to the US, perfected the first shellac moulded gramophone record, which boosted the demand of lac for nearly half a century.These records vastly improved the sound quality, were more durable and could be mass produced, in comparison to the earlier metal cylinders or cardboard ones coated with wax of Edison’s time. Gramophone records became obsolete in the 1980s, first by the advent of the cassette player, followed by CDs and DVDs.
  • The present synthetic polymer and plastics industry developed out of attempts to “synthesise” shellac in the laboratory, to challenge the monopoly of a few countries over the lac trade. Lac, in those days, was invaluable for the manufacture of moulded articles, electrical insulators, gramophone reords etc.
  • In 1872, Prof. Bayer obtained a resinous product, by heating phenol and formaldehyde together. This work was continued by W.H. Stoy (1895). Finally, Prof. L.H.Baekeland reported the synthesis of “bakelite” in 1909, ushering the ‘plastic age’, which continues till the present times.
  • Lac could not be synthesised artificially in the laboratory (even till today), but attempts to produce “synthetic lac” (see above) ultimately produced a wide range of polymers and plastics, which managed to replace lac from many of its traditional uses.

 

Lac Hosts

  • The lac insect belong  to  the category of primitive  insect called coccids.
    Coccids are notorious pests of forest vegetation,  on  woody trees and indoor ornamentals all over the world. However, the lac insect, which is technically a parasite of trees such as Schleichera oleosa (vern: kusum), Zizyphus mauritiana (vern: ber) and Butea monosperma (vern: palas) in India and of the rain tree, Samanea saman in south east Asia e.g. Thailand, cannot be considered a pest, since the economic benefits it produces far exceeds the negligible damage that it may cause to its host trees.
  • Conversely, a lac infestation on the sandalwood tree (Santalum album) is a problem (as in some cases in southern India) and definitely needs to be eradicated. Reports from Thailand indicate that the lac insect became a serious pest of fruit trees of longan and litchi, so much so that the insects had to be controlled by chemical and bio-control methods!! Some lac host trees in other countries are Anona squamosa (Myanmar), Dalbergia hupiana and Protium serratum (Vietnam), Acacia arabica (Pakistan) and Ficus carica (Russia). Amongst the dwarf host plants, Cajanus  cajan appears to be a universally accepted host in India, Vietnam and possibly, China.

Strengths, Weaknesses, Opportunities and Threats 

Lac and its associated products have managed to survive and create a niche market of their own, especially in western countries. Recent reports indicate that export destination for Indian lac is: Indonesia > Germany > USA. The reason behind the success of this forest – based commodity is due to a combination of strengths, which include:

  • Ability to form films on various surfaces 
  • Electrical insulating properties
  • Moulding properties
  • Adhesive & binding properties
  • Flavourless, odourless and edible properties
  • Decorative & protective properties
  • Medicinal properties
  • Inflammable properties
  • Ability to yield useful acids on hydrolysis

The fact remains that such a combination of properties cannot be mimicked by any synthetic substitute. Such inherent strengths ensure that lac can be used in diverse areas: from gun powder to lipsticks, chocolates and medicinal tablets, from perfumes to etch primers, etc. In fact, lac has faced continuous challenges from the synthetic petrochemical – based resins and dyes for over fifty years. In spite of certain basic weaknesses (lack of flexibility, solubility in alcoholic solvents, lack of sufficient water resistance and erratic supply position), it has managed to preserve its existence and also develop newer vistas of application and opportunities, in the face of continuous threats from synthetic substitutes.

 

FROM LAC TO SHELLAC

The life cycle of lac insect generally occur twice a year and insect behaves in two ways depending upon the host tree species that is either Kusum (Kusumi Strains) or hosts other than Kusum Tree(Rangeeni strains).

Lac is not always left on the trees until it matures fully, particularly in case of Baisakhi crops. When it is not mature it (Baisakhi-ari) is cut, living a certain amount on the tree to act as a brood for the next crop. In other crops, Lac is not required for brood purposes and is usually cut before the female insects are fully matured.

The Lac encrustation is separated by knife or broken off with finger from the twigs of host plants and it is known as Sticklac. The Sticklac, after grinding and washing, is called Chowri or Seedlac. The manufactured products prepared from Sticklac after washing and melting, which takes the form of yellow coloured flakes, is called shellac. After melting process, Lac is dropped on a Zinc sheet and allowed to spread out into round discs of about 3″ diameter and 1/4″ thickness is called buttonlac.

Process-of-Lac-Collection


PROPERTIES OF SHELLAC
TABLE IGeneral Physical Properties
TABLE IIMechanical Properties
TABLE IIIThermal Properties
TABLE IVElectrical Properties
TABLE VChemical Constants
TABLE VIPhysical & Chemical Constants

 

APPLICATIONS OF SHELLAC

Pharmaceuticals – Shellac is used to coat enteric pills so that they do not dissolve in the stomach, but in the lower intestine, which alleviates upset stomachs. Its also used as a coating on pills to “time release” medication.

Confectionery – Shellac is used to provide protective candy coatings or glazes on candies like Reese’s Pieces, because of its unique ability to provide a high gloss in relatively thin coatings (like a French Polish). It was used at one time on M&M’s. It is approved by the FDA as a food safe coating when dissolved in pure ethanol (not denatured).

Hats – Shellac is used to stiffen felt used to make hats. It allows the makers to shape the felt into brims, bowl shapes, etc.

Food Coatings – Because of its FDA approval, shellac is used to coat apples and other fruits to make them shinier. 

Electrical – Shellac mixed with marble dust is used by lamp manufacturers to glue the metal base to glass incandescent bulbs.

Other uses for shellac are in the manufacture of grinding wheels (it allows the abrasive particles to break off at the low heat generated by the grinding process, thus exposing new, fresh abrasive particles), leather finishing and painting (shellac pigmented with white titanium dioxide is widely used by painters as a stain sealer, wall board primer, and knot and sap sealer on wood).

Other former uses for shellac are electrical insulators, as a glue (it bonds glass and metal surprisingly well), phonograph records (the old 78′s were a mixture of shellac, fillers and lampblack), hair spray, no-rub floor polishes, and as a finish for bowling alleys (the weight of the ball dropping on the shellac surface did crack the finish).