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Handyman in the Home by Hobby
How Shellac Is Manufactured
T^HE shellac of commerce is a resi nous material, produced by anj insect, the only resin known to be of animal oriein. To be more accurate.
it is known as lac, but,- as it is mar keted in the well-known flaky form, it is more commonly known as shellac. Lac is the secretion of the lac insect, scientifically called laccifer lacca. One of the scale insects to be found on the twigs of certain trees in India. The body of the insect contains a dye, which must not be confused with the resinous secretion. It was this dye that was originally sought after, and not the resin. Lac dye is seldom used now, and has lost its commercial importance. The resin is the only product of the insect that is valued. It is interesting to note that the word lakh means 100,000, and has been ap plied to the secretion of the insects on account of such myriads swarming to gether on the trees. References to lac having been used as early as 1596 in the preparation of varnishes for wood have been found. The lac insect begins life as a minute creature about 1-40 in. in length. It is provided with a fine, hair-like tubular proboscis with which to pierce the soft structure of the tree and suck out the vegetable juices. The insect lives on these juices, and, during its life, it secretes the resinous matter. This provides it with a pro tective covering against its many ene mies, both insect and bird. * ? ? THE lac insect achieves its life's ob , ject in the propagation of its kind. After the young emerge from the al ready dead bodies of the female, the secretions that provided them with protection and shelter become the raw material of the lac industry. The industry is important in India, as practically the whole of the world's supply comes from that country. The insect is actually a parasite, and, to prevent the host trees from becom ing extinct, the industry is carefully supervised. Trees are selected and pruned to encourage the growth of young, tender shoots, which are then infected with the young insects. Time for recuperation is given the trees. In some instances they are fertilised to .help them along. When the life cycle of the insect is complete and the young have emerged, the old lac-encrusted twigs are gathered.
The first stage in the process of manufacture is to remove the lac from the twigs, this being done with knives, the product being known as stick-lac. On being crushed in special mills, the stick-lac is converted into seed-lac, which is washed to remove all im purities. The next step is to prepare the seed lac in its various forms for export, namely, shellac, garnet lac, and button lac. Of these three, the most import ant is shellac. It is prepared by melt ing the seed-lac in long, cylindrical cloth containers before a charcoal fire, causing the molten lac to filter through the cloth on to a stone slab. By rolling this mass of lac with an earthenware cylinder, filled with hot water, it is worked into a sheet of
even thickness. The skllleid nature workman, holding two corners with his toes, and gripping the upper edge with hands and teeth, rapidly stretches the thick sheet until it becomes very thin. On cooling, it is broken into the small pieces with which we are familiar. * * * A N estimate has been made that half ?£i- of the shellac used today goes into the manufacture of gramophone records. The preparation of spirit varnishes and polishes absorbs a large proportion of the annual output. French polishing as a trade is entirely dependent on the shellac industry, there being no other product to take its place. Electrical industries use shellac be cause of its high insulating properties. It is also used in the manufacture of munitions on account of its waterproof ing qualities and in the making of first grade sealing waxes. Although french polishing has reached a fine art, it still has some disadvantages. It is quickly marked by heat and water. However, these de fects are being taken into account, and it is expected that in the near future a polish containing a chemical hardener will be introduced. This polish would be used where increased resistance to water and heat is required. For polishing light-colored woods a specially prepared bleached shellac is available to give a clear finish to the work. * * * BOOT POLISH TIDY nr*HE illustration shows a handy little -*- article, easy to make and always useful. It can be made of % in. ply wood, but one of the softwoods, as used for packing cases, would be more suit able. An important point when making boxes of any kind is to work the sides together, and then the ends, to make them exactly the same size. The ends must be right-angular. When all the pieces are of the cor rect size they can be cleaned up with
a smoothing plane and glasspapered in readiness for nailing. Use 1% in. round head nails, about three to an end. If they are nailed on the slant a very serviceable job will result. Punch the nail-heads below the sur face and plastic-wood or putty the holes made. Finish off with glasspaper. A .stain or varnish would be suitable for this box. Some form of grip can be attached if the tidy is to be fitted in a cupboard or shelf. i