COMMERCIAL PRODUCTION OF LAC
Lac cultivation is a complicated process. Proper care of the host plants, the propagation process and the collection of lac are the prominent steps in the cultivation of lac. The following are the process involved in the cultivation of lac:
- Selection of site and the host plants
- Harvesting of lac
Selection of site and the host plants
The selection of suitable host plants is of primary importance in lac cultivation as the quality and yield of the lac is directly proportional to the host plant number. The host plants include Babul, Pipal, Palas, Kusum, Khair etc. So, the site for the cultivation should have more and more numbers of the host plants.
The host plants must be quick growing, have low sap density, able to withstand heavy infestation of the lac insects. Of all the plants stated above, the lac from the host plant Kusum (Schleichera trijuga) attracts highest price in the market. Then comes the host plants like Palas (Butea frondosa), Ber (Zizyphus jujuba), sirrus (Albizzia lebbak)
The time of pruning also plays a prominent role in lac production. During pruning, proper care of the host plant is needed so that the host plants do not loose health, nutrition and also produce better quality and quantity of lac.
Pruning is generally done 6-12 months before inoculation of lac insect. The normal time of pruning is January-February if inoculation is to be done in June-July and pruning time is April-May is inoculation is to be done in October-November. The following points must be taken care of during pruning:
- Avoid excessive pruning. This helps in maintaining general health and strength of the tree.
- Cut only old branches of the host plant. Branches more than two inches of diameter must not be cut.
- Allow good shape of the tree to allow plenty of room for the growth of new shoots.
- Cut thin branches close to the trunk from which they arise.
- Remove dead and diseased branches
- Cut the split or broken branches below the split or break
- Avoid indiscriminate cutting of the lac bearing branches.
Inoculation is the first step in the cultivation of the lac insect. It is the process whereby the young ones get associated properly with the host plants. Inoculation can be done in two ways namely, natural inoculation or artificial inoculation.
Natural inoculation takes place in normal routine and it is very simple process where the swarmed larvae infect and suck out the sap from the same host plant again. On the other hand in artificial inoculation the twigs bearing the insect larvae which are about to swarm are cut. These cut pieces are tied to fresh trees so that the larvae swarm out to the new host plant. Artificial inoculation is generally considered to check all possible drawbacks of natural inoculation.
Swarming is the important phase of the lac insect. At the time of swarming, the upper surface has yellow spot on the anal region. At this stage, the muscles contract and insect gets detached from the place of attachment. This leaves a hollow cavity which is later filled with resin. The exact time of swarming can be learned by experience.
Harvesting of lac
The process of collecting ready lac from host tree is known as harvesting. Harvesting can be of following two types:
Immature harvesting: Harvesting of the lac even before swarming is called immature harvesting. The lac thus obtained is called as Ari lac. This process has few drawbacks as the insects may be destroyed during harvesting and this will leave the cultivators in great loss. Ari lac harvesting is recommended only on Palas host plants.
Mature harvesting: Harvesting of the lac after swarming is called mature harvesting. The lac thus collected is called as mature lac.
The largest yield of lac is obtained by harvesting twigs with the females still living. Harvesting can be done twice a year. The twig bearing the lac along with the eggs is called brood lac stick and the lac is called as brood lack or stick lac.
PROCESSING OF LAC
Processing is done, after harvesting of the lac from the host plants. Processing starts with the scraping of the stick lac from the twig. Now this scrapped lac must be cleaned of the impurities like dead lac insects, eggs and coloring matter. After cleaning the lac is finally crushed with the help of hand-operated mortars. This crushed lac is air dried after which it forms pale yellow colored granules. This is called as seed lac.
Seed lac is then soaked in water, washed, dried in sunlight, bleached and heated to melt in on charcoal file in cloth bag. During heating the bag is twisted and the lac is squeezed out of the bag with the impurities left out in the bag. This lac is called as Kirri lac.
Kirri lac is allowed to cool down and solidify around button shaped forms to form button lac or pure lac. This pure lac is stretched into thin sheets called as sheet lac. The sheet lac when dissolved in water produces white or orange colored lac called as shell lac.
The quality of the lac depends on the host plant. Kusumi lac is said to be the best and costly lac while dhak lac is said to be the worst and the cheapest one. The quality and the color of the lac vary depending on the presence of gum and resins in the host plant.
Types of lac
Ari lac- It is immature lac harvested from the host plants
Stick lac- It is matured lac harvested in the form of stick from host plants
Seed lac- It is obtained after removing and washing the lac from the stick
Dust lac- It is obtained after grinding seed lac
Shellac- It is prepared after heating the seed lac and dust lack
Composition of lac
Lac is a complex substance and it also contains sugar, water and other alkaline substances along with large amounts of resins. The percentages of various constituents ate as follows:
Albuminous matter- 5-10%
Mineral matter- 3-7%
Uses of lac
Lac has been used for the welfare of human beings from the great olden days No doubt the development of many synthetic products have made its importance to a little lesser degree, but still it can be included in the list of necessary articles.
- Lac is not soluble in water but is readily soluble in alcohol. This property is used for insulation of electrical connections.
- Lac fuses easily on heating
- It has adhesive property
- When mixed with alcohol it exhibits binding properties
- It is also soluble in weak alkali like ammonia
- It is a bad conductor of heat and thus finds use in electrical appliances
LAC PRODUCTS AND THEIR USES
Lac dye is a mixture of anthroquinoid derivatives. The following are the uses of lac dye:
- It is traditionally used to colour wool and silk. Its colour varies between purple red, brown and orange often depending upon the mordant used.
- It is also used in food and beverages industry for colouring. In recent past, lac dye has been replaced by synthetic dye. But, now-a-days with increasing stress and awareness on use of eco-friendly and safe material, there is a great demand of lac dye as a colouring material.
Lac wax is a mixture of higher alcohols, acids and their esters. It is used in,
- Polishes applied on shoes, floor, automobiles etc.
- Food and confectionary
- Drug tablet finishing
Shellac is a natural gum resin. It is natural, nontoxic, physiologically harmless and edible resin. The following are the important uses of shellac,
- It is used in fruit coatings, e.g. for citrus fruits and apples, parting and glazing agents for sweets, marzipan, chocolate etc. Also used as binder for foodstuff stamp inks, e.g. for cheese and eggs.
- It is used as binder for mascara, nail varnish additive conditioning shampoo, film forming agent for hair spray, micro-encapsulation for perfumes.
- It is used for enteric coatings for tablets and as odour barrier
- It is used in manufacturing of photographic material, lithographic ink and for stiffening felt and hat material.
- It is utilized in preparation of gramophone records.
- Jewellers and goldsmiths use lac as a filling material in the hollows in ornaments.
- It is also used in preparation of toys, buttons, pottery and artificial leather.
- It is also used commonly as sealing wax.
- With increasing environmental awareness of consumers, this natural and renewable raw material is being used in the development of new products like,
- Leather: Seasoning, Leather care products
- Printing inks: As binder for flexographic printing inks for non-toxic printing of food packaging
- Wood treatment: Primers, polishes, matt finishes
- Textiles: As stiffeners
- Electrical: Insulation, capping, lamination
- Abrasives: Binder for grinding wheels
- Others: Binder for inks and water colours, Micro-encapsulation for dyes
Bleached shellac is non-toxic, physiologically harmless (edible), and is widely used in the food industries, food packaging and allied industries. Apart from the above, bleached shellac is also used for its qualities i.e. binding, adhesive, hardening, gloss, odourless, fast drying, and extending shelf life (in absence of refrigeration ) etc. Clear and transparent or very light coloured alcoholic or water - alkali solutions can be obtained from bleached shellac. Bleached shellac is widely used in the following industry:
- Paints (as primer for plastic parts and plastic film)
- Aluminium industry (as primer for Aluminium and Aluminium foils)
- Flexographic printing inks
- Pharmaceuticals (for coating of pills, tables and gel caps and coating for controlled release preparation)
- Confectionery (in coating of confections, chewing gums, marzipan chocolates, nutties, jelly- and coffee-beans etc)
- Binder for food marking and stamping inks and Binder for egg coating
- Barrier coating for processed food, vegetables, fruits and dry flowers
- Textiles (used as textile auxiliaries and felt hat stiffening agents)
- Cosmetics (used in hair spray, hair and lacquers, hair shampoos, and binder for mascara)
- Wood finishing (as binder for wood coatings and wood stains and as filler/sealer for porous surfaces and cracks)
- Antique frames for paintings and Wood polish (French polish)
- Fireworks and pyrotechnics ( as binder for fireworks, matches etc and used in coating of magnesia
- Electrically as binder for lamp cements
- Electronically it is binder for insulation materials, serves as additive to moulding compounds. Mass coating for print-plates and is adhesive for si-cells.
- Grinding wheels (it is binder for additive of grinding wheels)
- Plastic (it is primer for plastic parts and films)
- Rubber (it is additive to natural rubber)
- Leather (in leather auxiliaries)
Dewaxed bleached shellac
Dewaxed white shellac is used in the same way as any other grade of shellac. The major difference between this shellac and the others is that it is a bit harder, shines a bit brighter, is completely free from wax. Bleached lac has super characteristics and qualities i.e. adhesive, binding, hardening, gloss, odourless. It has good film forming properties, a high gloss and excellent adhesion to various substrates including the human hair. It is non-toxic and physiologically harmless. Good solution can be obtained in ethanol and lower alcohols. It can also be dissolved in water by adding an alkali like Ammonia. It is compatible with many other resins, raw materials and additives used in cosmetics, pharmaceuticals and food formulations. It is used in,
- Coating of fruits and vegetables
- Coating in tablets & capsules
- Coating in confectionary
- Coating in aluminium foil, paper
- Coating in cosmetic industry
- In cosmetics, it is used in hair sprays (pump sprays or aerosol sprays, hair setting lotions, hair shampoos, mascara, eyeliners, nail polishes, lipsticks, micro encapsulation by coacervation of fragrances and perfume oils.
- In food, it is used for coating of confections, chewing gum, candles, cakes, eggs, citrus fruits and apples, and printing inks for eggs and cheese.
Aleuritic Acid (Shellac Aleuritic Powder)
Aleuritic Acid (9, 10, 16-trihydroxypalmitic acid), obtained from shellac by saponification, is a unique acid containing three hydroxyl groups of which two are of adjacent carbon atoms. Aleuritic Acid is white powder or granule. It is moderately soluble in hot water or lower alcohols (viz. methyl alcohol, ethyl alcohol, and isopropyl alcohol) and crystallizes out on cooling the solution. It is soluble in the lower alcohols such as methyl, ethyl and isopropyl alcohols. Technical grade Aleuritic Acid (purity 99%) a slight yellow and almost odourless solid. The uses are,
- There is a continuous growing demand of Aleuritic acid in the fields of perfumery and pharmaceuticals due to it being an excellent starting material for the synthesis of civetone, ambrettolide, isoambrettolide etc, which have the musk like odour. Civetone is obtained from Shellac Aleuritic Acid.
- It is used for manufacturing of perfumes and is very much in demand with perfume manufacturing companies in France, Italy, Germany, USA etc.
- Synthesis of Glucose monoaleuritate (a non-toxic non-hemolytic water-soluble compound) in medicine as an isocaloric substitute for dietary tripalmitin.
- Preparation of plastics with good adhesive properties by the condensation of Aleuritic acid with pithalic andydride and glycerin, rosin etc.
- Aleuritic acid esters used in the preparation of lacquers, plastics and fibres.
- Explain the steps incolved in the commercial cultivation of lac.
- What is pruning? What are the points to be taken care of while pruning?
- Write about the harvesting of the lac. Also mention types of harvesting.
- What are different types of lac. Define each of them..
- Write the composition of lac.
- Enumerate the uses of Lac.
- Write the used of shellac.
- Enumerate the uses of Bleached shellac.
- What are the uses of dewaxed bleached shellac.
- Differentiate between the uses of lac dye and lac wax.
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