Making Chamois leather through

Making Chamois leather through combination tanning

In India, the highest quality chamois leathers are made through a combination of aldehyde and oil tanning. The resulting leather has all the properties of Chamois  leather. Goat skin is used for this and the process is very fast.

Raw skin:

Salted and salted goat skin is used for this purpose. Skin that has hair loss or has a flawed face is considered for this purpose. Raw skins of medium size and to a large extent are selected for this purpose.

Soking:

The skin is soaked in water for 2 to 6 hours. After this period, the sucking bath is changed 2 to 3 times and the complete shell is washed. Then they are made of porcelain to drain their water.

Lime:

Hair removal is done by applying materials to the skin. The composition of the dough used is:

Concentrated sodium sulfide one part

Hydrated lime 6 parts

– Water 12 parts.

Grinding is done with a brush. Shaved skin is kept shaved overnight. The next morning, after hair removal, the pellets enter the lime bath, which has been used once before. The skin stays in this bath for three days and nights. Every day the skins are weighed and re-entered the bath. On the fourth day, the skins are transferred to a freshly prepared lime bath. This bath has 10% lime and 1-2.5% soda.

The skins are kept in the new bath for 4-5 days. And when the pellets are well swollen and thick, some white lime is added to the bath. The skins are then prepared for calcareous asphalt. If the skin is not asphalted at this stage, it can be rubbed normally.

Crushing:

The finished waxing pellets are taken out of the lime bath and placed in a soft water bath overnight. The next day they are slaughtered. The crushed pellet is washed and weighed 2-3 times.

Lime extraction:

Lime extraction is performed using boric acid or acetic acid in the amount of 1.4-1%. In the drum, the limeing operation is usually completed within an hour. Lime calcification should be controlled by phenolphthalein test.

Scudding:

Lime pellets are squaded.

Tanning:

Scattered pellets enter the drum with 200% water. 3-4% formaldehyde and 1% soda are dissolved in water and added to the rotating drum. The increase of these materials is done in three steps with a time sequence of 30 minutes. The drum rotates with these materials for 4-5 hours to do the tanning. It is then drained and drained after the porcelain vault.

Turning:

If the asphalt has not been done after liming, the dehydrated leathers will be machined, and the forging operation will be performed on both the surface and the surface. Re-weighed, thoroughly washed and dehydrated.

Oily tanning: For emulsion tanning, fish oil is prepared as follows:

– 30% fish oil (based on falsified weight)

– Soda 0.5 percent

– 8% plaster

– 8% water

If needed, 2% hydrated lime or 1% ammonia can be used instead of soda. First, fish oil is mixed with gypsum in a bucket. Soda should be dissolved in warm water and added to a mixture of oil and gypsum. The new mixture is thoroughly stirred to form an emulsion. False and dehydrated pellets are inserted into the drum and the upper half of the emulsion is fed from the funnel to the drum. After twenty minutes of drum rotation, the other half of the emulsion is added. And the drum spins for 10 to 12 hours. The leathers are then drained from the drum.

Drying and oxidation:

The leathers are hung in a closed chamber for 7 to 10 days for oxidation. During this period, the color of the leather should be the same golden yellow.

Wash:

Dried leathers are washed 3-4 times with 1.5% warm soda solution to release unmixed oils. The washing method is as follows: to wash 45 kg of dry leather, 1.3 kg of soda is dissolved in 45 liters of water at 40 ° C and washed for 30 minutes. The water is drained and then the leathers are washed three more times in the same way as in the first series. Then the leathers are washed for half an hour with a solution obtained by dissolving half a kilogram of detergent in 45 liters of water at 40 degrees Celsius.

Finally, it is washed once with cold water. Between washing with soda, if the leathers are squashed, the removal of the combined oils is facilitated. Washed leathers are hung on the table with a dehydrated spatula to dry, the leather should be golden yellow and not gray. After drying, the leathers are soft and clamped and removed. Then both sides are rounded with plaster to be ready for sanding. Both the lash side and the face side are sanded with 280 paper. In this case, the leathers are ready to use. Therefore, they can be cut to any size.

Factors influencing the manufacture of Chamois  leather

1- The oils used in making Chamois  leather can be easily oxidized if they have at least four double bonds.

  1. Oiled leathers should be exposed to air to oxidize the absorbed oil

3- The air in which the leather is hung to dry must be moist. The use of chambers that regulate temperature and humidity is suitable for this purpose. Using air with a high percentage of humidity is suitable for this purpose.

  1. Tanning agents such as acrolein and other bad-smelling aldehydes are released during aeration. Marine oils and their fatty acids can both do the tanning.

The released glycerin has no tanning power.

Use other ingredients for tanning

During World War II, a new method of tanning was used in Germany. In this method, saturated hydrocarbon sulfonyl chloride was used for tanning. This material was made by BASF company and was marketed under the brand name of Amargan. Leathers made with this material are very strong white, have high light stability and are resistant to alkalis and washing. In Amrgan, the sulfochloride radical combines with the skin’s collagen fiber group to produce hydrochloric acid. Therefore, to advance the reaction, a sufficient amount of soda must be used to neutralize the acid produced.

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Chamois leather

Making Chamois leather through combination tanning

Translator: Mr. Ebadollah Yousefzadeh (Eng.)

Leather University Professor

Source:

Theory and practice of leather manufacture .By: K.T .sarkara.by the C.L.S .press .Madras.1991

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