Aldehyd AG is an auxiliary substance for the tanning industry. It is an aldehyde tanning agent for the retannage of mainly chromium-tanned leather. The product is also designed for individual and combined retanning (aluminium-aldehyde or chrome-aldehyde) of fur leather.
Aldehyd AG is a product of formaldehyde polymerization. It is a colourless to light straw liquid. It is characterized by excellent solubility in hot and cold water. Methanol, ethanol and acetone cause the separation of some of the components from the product. Aldehyd AG is resistant to acids, salts and alkalis used in the leather tanning.
It forms mixtures with chromium, aluminium and aldehydic tannins, dispersing and filling agents and anionic greasing agents. Its advantage is the freezing point below -12 ° C, which facilitates transport and storage of this product.
Aldehyd AG is a product that can be used for tanning on its own. Thermal resistance of leathers tanned with its use is comparable with the level of thermal resistance of leathers tanned with formaldehyde or glutaraldehyde. Compared to formaldehyde tanning, the leather tanned with Aldehyd AG is distinguished by a slightly higher solidity and plumpness. Compared to glutaraldehyde tanning – a more favourable white colour of leather is achieved.
Leathers tanned using Aldehyd AG have the typical advantages of aldehyde tanning, i.e. good resistance to sweat, alkali and laundry detergents. An important feature in the case of chrome tanning is its filling, softening and smoothing effect on leather. Chrome tanned leathers retanned with Aldehyd AG also have better dyeing properties. With its weak equalising properties, the product does not cause excessive brightening of the leather dyed with anionic dyes.
The affinity of Aldehyd AG for the rawhide and the chrome tanned leather increases with higher pH, similar to the affinity of chromium tannins. The best preparation for retanning of chrome tanned leather is the mixture of Aldehyd AG with aluminium salts, ipoglin Al or Cr. The effect of the filling is related to improving the solidity of the retanned leathers.