At what ideal conditions, pickling can be carried out?
The concentration of the pickle bath should not be below 6°Be otherwise will result in irreversible acid swelling of the skin. Excessive salt will result in flat, thin leather, low salt or salt free pickling is possible with non-swelling aromatic sulphonic acid. Temperature and pH value plays very important role in pickling. If the pickling pH value is < 3.2 penetration of chrome tanning agent is quicker however large quantity of basifying agents have to be added. If the pH value is > 3.8 – 4.0 superficial precipitation may occur, especially with unmasked tanning agent, which produce stains and make complete penetration of the tanning more difficult. The ideal temperature range is 20°-30°C. Temperature below 20°C should be avoided because of the risk of low temperature swelling and temperature exceeding 30°C result in damage to the grain. Ideal float of pickle is 75% to 100% brine solution on pelt weight.
