At the present time, two types of fat liquors predominate.
1. The mayonnaise-type fatliquor which is oil in soap, or soap and a protective colloid.
2. Sulfated oil of various types.
a. Animal fat oils
Tallow and stearines, card oil sheep oil neat’s-foot oil wool grease.
b. Vegetable oils
Corn, Cottonseed oil, olive oil, castor oil oiticica palm oil coconut oil, soybean oil, rice bran oil
c. Marine oil
Sperm oil menhaden oil sardine oil red fish code oil herring oil
d. Moellon and degras
e. Oil substitute-German synthetics
f. Mineral oils and sulfonates.
Oils vary in their melting and boiling points interfacial tension against water, polar characteristics, viscosity etc. the cause of these differences is the chemical structure of the various fats and oils. In above figure with the exception of wool grease and sperm oil, the others listed in group a, b and c consists mainly of triglycerides.
a. Castor oil
This is the only commercially imported oil containing major amounts of hydroxyl acid this acid is called recinoleic acid and has one double bond in addition to the hydroxyl group present in the chain the following analysis of a sample of castor oil was reported by Kaufmann and Bornherclt.Analysis of castor oil
Iodine value (Kaufmann) ......85.8
Saponification value ..............294.4
Saturated acids ....................2.4
Oleic acid............................ 7.4
Recinoleic acid.................... 87.0
Linoleic acid......................... 3.1
Physically castor oil is distinguished from other oils by its high specific gravity compared to other oils of comparable iodine value. Unlike other oils, it is miscible with alcohol, but is only slightly soluble in petroleum other at room temperature. This demonstrates it’s highly polar-nature. It is much more viscous than other oil and melting points of its fatty acid (about 3⁰ C ) is lower than that of any other common oil of equivalent unsaturation.
b. Code oil
Code oil, because of its price and its chemical properties is very popular oil used in fatliquoring. The chemical characteristics of code oil vary greatly with the source and method of rendering the oil. Code oil has less saturated acids do not appear to be different from most fishy body oils.
c. Neatsfoot oil
This is a special inedible fat of low melting point rendered from the shin-bones and fact of cattle there are various graded of Neatsfoot oil designated by cold test, the most popular for leather purposes being 20 ⁰ C cold test and 10 ⁰ C cold test.
d. Wool grease
Wool grease, because of the high content of wool wax falls into a class alone. Sheep`s wool contains greasy matter which consists, for the most part, of ester waxes in which the alcohol are a mixture of sterols such cholesterol, iso cholesterol, lanoserol.
e. Moellon
Moellon is a term generally applied to the fish oils which are removed from chamois after the tanning process. There are two distinctly different methods of removal, one being the cold bressing of the skins and the other being the removal by drum washing in the presence of an alkali such as soda ash. The products of these two processes are quite different, the former containing an appreciable quantity of sheep grease. The constituents of Moellon which makes it a valued product in the production of leather are the oxidised and polymerized fish oils.
f. Sperm oil
Sperm oil used in fatliquoring is largely the body oil of the sperm whale. It differs from most other oils since it contains large quantities of esters (waxes) of higher aliphatic alcohols the crude oil contains up to 75 % waxes, the balances being triglycerides. From the standpoint of fatliquoring, this is imported because during sulfation there is some hydrolysis of the waxes resulting in the production of sulfated alcohols. These are powerful emulsifiers, causing a higher degree of penetration of the fatliquor into the leather. 
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