Roksol ST4A is an anionic auxiliary agent used in tanning. It is used to lubricate leather, mainly in chrome tanning. The product is a mixture of anionic emulsifiers and aliphatic compounds containing carboxyl groups. Its commercial form is an O/W type emulsion (oil in water), beige to brown in colour, with a tendency to delaminate. Due to the solidification point (below -5°C), the product does not require special storage and transport conditions.
Roksol ST4A is resistant to acids, alkalis and electrolytes. It is characterized by limited ability to mix with tanning salts of chromium and aluminium. The product has the ability to emulsify crude, natural and mineral fats. In addition, it can be mixed with all anionic and non-ionic lubricants. It is also possible to prepare so-called multi-charged compositions with the use of Roksol ST4A and cationic fats, e.g. Roksol ST3K. Its ability to mix with clearly cationic or anionic compounds (syntans, vegetable tanning agents) depends on the conditions and needs to be verified in each case.
The product is resistant to oxidation and sunlight. It has a high softening effect on the chrome tanned leather as well as moderate equalising and hydrophobic properties. Its moderate equalising effect enables obtaining pure and vivid colours when dyeing skins with anionic dyes.