Q1. What are Fatliquors?

Fatliquors basically are lubricants for leather. The final softness, feel and touch of leather are determined by use of different fatliquors.

Technically fatliquors are surface-active softening agents and are used in the last of the wet processes stage of leather manufacture.

Q2. How many types of Fatliquors are prevalent in the market?

Basically speaking there are three categories of fatliquors.

• Natural oil based
• Semi synthetic
• Synthetic

The above three categories are further divided into four types

• Anionic
• Cationic
• Non-ionic
• Amphoteric

Q3. How are fatliquors used to soften leather?

Fatliquors are used in form of emulsions in rotating drums in which chrome, aluminum or vegetable tanned leathers are put. It takes some time for oils in form of emulsions to penetrate the leather, get dispersed and fixed. Some part of the fatliquor is dispersed in neutral form and some part of it is chemically fixed with the leather fibre.

Q4. How are fatliquor emulsions prepared?

Generally fatliquors make oil in water emulsions. To produce such an emulsion fatliquor is added to a minimum of four times it volume of water at about 60°C if possible and added to the drum. Some fatliquors are designed to make water in oil emulsions such as water repellant and cationic fatliquors. In this water is gradually added to the fatliquor to get the emulsion.

Q5. Does higher temperature of water effect the efficiency of fatliquor emulsion?

Yes it could, as some fatliquor contain coupling agents, which are volatile and at higher temperature escape from the system and could reduce the stability of emulsions.

Q6. What other conditions could impair the stability of emulsions?

1. Use of live steam to heat emulsions should be avoided since local superheating could affect the stability of emulsions.
2. Emulsions should not be allowed to stand for a long time and should be used as soon as possible.
3. As far as possible, soft water should be used to make emulsions. Some emulsions are not stable to hard water.

Q7. Is it necessary to use additional emulsifiers to stabilize emulsions?

No, it is not necessary to add emulsifiers as most fatliquors are already stabilized to a reasonable extent. Any additional emulsifier could overstabilise the system resulting in poor exhaustion of the bath.

Q8. If we have to use different fatliquors in one particular process, how do we go about preparing the emulsions?

When different fatliquors are to be used they should be blended thoroughly together first and then added to water to make oil in water emulsion or vice-versa.

Q9. What are the criteria of blending fatliquors?

Basically, it depends on the sort of leather to be manufactured. Care should be taken to balance a ratio of deep penetrating to surface lubricating type in a manner so as to achieve a desired lubrication throughout the cross-section of leather.

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