- Leather hides: These are wet salted hides of certain ruminants, sourced from Bhuj, Bhavnagar, Rajkot, Ahmedabad and Chennai.
- Okhai baavad: It is the locally available species of Acacia Arabica with yellow flowers; indigenous tanning materials are obtained from this tree.
- Liming mixture: Sodium sulphide, slaked lime and water are used as liming mixture; they help in complete removal of hairs and produce changes in skin collagen, the skin collagen swells and results in more open structure of leather.
- Deliming solution: Ammonium sulphide, ammonium chloride, water constitute the deliming solution. This makes leather structure to become more open, the remaining impurities is also removed through deliming.
- Castor oil: Castor oil is derived from Castor seeds, it can be colorless or pale yellow with very mild odor or taste. It is considered best for leather treatment; it elevates the longevity of leather products.
- Dori: To impart strength in leather joints, double twisted cotton twine is used for sewing usually waxed after being dipped into the wax previously.
- Leather ribbons: Very thin and narrow leather threads, either obtained as by-products from leather cutting or intentionally cut, are used in various decorative patterns; these are also used to form braids, borders, straps etc.
- Chikni maati: It is local name for the mud from the pond beds or river banks which is used as adhesive. This is thinner than dendrite. It does not harden the edges like dendrite solution and makes the leather, easier to be sewn.
- Chemical dyes: These are chemically derived dyes. After the application on leather, the solvent either evaporates or gets absorbed and the color penetrates into the leather exuding the desired color.
- Embroidery threads: Zari(gold/silver plastic), Torni(cotton ply yarn), Fhumka(pompoms) are the major embroidery threads.
- Mirror: Mirrors are utilized for detailed inlay work, for decorative purposes small pieces of mirrors are inlaid in certain products. For the products such as hand mirrors or wall hanging mirrors, comparatively large pieces of mirror are inlaid between two layers of leather.
Leather making has raised serious environmental issues, from the use of harmful chemicals and pesticides to the problem concerning disposal of organic wastes at tanneries. The leather industry is also gradually polluting underground water of several regions across the country. The chromium compounds, sulphides, ammonium salts involved in tanning process are known to be responsible to land, water, air pollution. 20 to 40 tonne of water is wasted for one tone of leather production in tanneries.
Even traditional Charma Karya process involves wastes that can substantially harm the environment, as the leather sourced is more or less derived through chemical processes. But artisans are now drifting towards the artificial alternatives to leather, like Rexine. Rexine is environmentally friendly and feels like leather. The process of embroidery and punch work, more or less remains the same.
Tools & Technology
- Kol: Tool made from buffalo horn which is used as a container to pour water into the skin bag while processing leather
- Krapli: A marking knife with a narrow, slightly convex blade and a small handle. These blades are sharpened on both sides. The craftsmen use it to mark lines by pressing it onto the leather.
- Kagaj na farmo: Paper templates which are standardized sizes for the different leather objects.
- Karpa: A scraper which has a semicircular iron blade. The edge is straight and only slightly sharpened. The blade is fixed in a cylindrical wooden handle. This is used to treat the surface of the leather.
- Rapi: A scraping knife with a long trapezoid blade in a straight edge leading to a wooden handle. It is sharpened on both sides to a keen edge. The rapi is used to both cut and scrape off leather.
- Moti aur nanhi arhi: Large and small awls which consist of iron pins fixed to a cylindrical wooden handle. Its point is hammered flat and the edge is sharpened to a slightly convex shape. These are used to pierce the holes in the seams. There are 4-5 types of arhis depending on the thickness of the leather and the threads or doras in use.
- Sui: Common needle with a large eye threaded with a string.
- Punches: Used to make holes and patterns on the leather articles. They come in various shapes like stars, diamonds, squares, rectangles, circles, flowers etc.
- Rampi: This is similar to the scraping tool except that the blade is not sharpened so as to not cut the leather.
- Hathodi: Hammer with a short wooden handle.
- Mogri: Iron beetle which is a tapering cylinder with a broad head made of cast iron, used to treat leather and pound seams.
- Dhoka: Simple wooden cylinder with a flattened end. This wooden beetle is used to pound leather and used as a support while doing embroidery.
- Salari: Stone slab of fine crystalline sandstone used as a base or support.
- Kalbut: A stretching last in the shape of the shoe in the standard sizes. It is made from carved baval wood.
- Cutter or blade: Used to cut threads while doing embroidery.
- Wooden stick: A tool used for embroidery and also used while making torni.
The tanning process prevents putrefaction and imparts durability to the leather. It also makes it firm, supple and impervious. The people who convert raw hide into leather are known as 'chamars' in Indian society. The process of vegetable tanning done by the chamars is as follows:
Cleaning and drying
The fresh hides are first washed in plain water. The inner side of the hide is plastered with mud or salt and spread out flat. It is also sometimes held by pegs to prevent contraction. This is then dried and scraped with a blunt instrument to remove dirt particles. It is again spread flat to remove the creases and folds.
The liming process makes the hides swell to make it porous and permeable for the tanning solution. The hide is sprinkled with milk extracts of 'aankda na phool' and with a solution of water and salt. This is done once or twice in a day, for a period of 14 days. A goat hair brush is used to spread this solution on the hide or it is done by hand. This is then folded and immersed into a pit containing the mixture. The skin is usually taken out every day, aired for an hour and immersed again.
Removal of hair
After liming, the water is wrung out and the hide is spread on a smooth surfaced stone. The liming makes the hair fall off easily. The hairs are scraped off using a blunt knife. Hide is then soaked for 2-3 hours. The adherent flesh and fat on the inner side is then scraped clean with a sharp knife. This step takes one whole day. After this, the hide is then put in clean running water and the lime is washed away.
Treading is done for 3-5 hours a day, while rubbing with hand is done 4-5 times. After 2-4 days, the hide is taken out and the moisture is squeezed out or it is pressed in a draining table. The hide is again soaked in a fresh and stronger solution of tannin mixture for 2-3 days. This process is repeated 5-6 times.
Infiltration process / bag process
The hides are sown together to resemble the masak or the leather water bag. The tannin liquor is then poured into this bag, which is suspended on bamboo bars. This facilitates proper impregnation of the hide with tannin. The process is repeated several times after which it is done with the bag turned inside out. The hide is occasionally beaten to test if the tanning is complete. If it produces a hard sound, it indicates the process is complete but if the sound is soft then the tanning is unsatisfactory.
The leather bag is opened out and stretched for partially drying. It is then rolled up and trampled for some time before it is unrolled. This makes the leather compact, soft and supple.
The outer side of the leather is scraped, rubbed and scoured with a knife. This process helps in removal of creases and the marks of the folds.
Polishing and Graining
The leather is now dressed with oil, mostly vegetable oil. They apply it over the leather using a smooth edged instrument or a glass bottle.
Coloring and varnishing
The village cobblers use primitive methods of coloring leather. The ingredients used in the tanning mixture like pods and barks of the acacia plant impart a particular color to the leather. This is usually imperfect and non-glossy. Usage of synthetic dyes makes the dye penetrate into the leather with the dye solvent evaporated or absorbed. Some leathers are further processed by application of upper coat finish. The top coat attaches itself to the surface with elevating the durability of leather. The pigmented finish might be taken into account, containing various colors, resins, lacquers, oils or waxes.
The Mojadi is prepared in three different layers and then assembled together. The layers are stuck with the Maati until stitched, using leather. First the top cover is embroidered and stitched with the sole and then the top of the sole is stitched for finishing. Embroidery is done with various silver and colored threads based on guidelines made with the Rapi. Water is applied to relax the holes while embroidering. Two separate pieces of embroidery is done- one for the top of the shoe/Varolo and the other for the inner sole. The sizes are molded using the Kalbuts. Tornis or Fhumkas are attached for embellishment.
The craftsmen procure the raw materials as per the size of the mirrors. The leather is cut into required shapes and these pieces are then punched as per the design. The designs vary from artisan to artisan. Clothes of various colors are made into strips and stitched to the leather piece. A cardboard piece is then cut by the craftsman according to the shape of the leather piece with backing cloth. Cardboard piece is then glued together with the leather piece so that the mirror is sandwiched between them. Torni is stitched finally to give the structural strength and mirror is cleaned with kerosene