Limed hides and skins are called "PELTS" and at this stage are free from hair and plump. The excess flesh from the flesh side is removed on fleshing machines or by hands.

The alkaline chemicals used in the liming process are still present in relatively large amounts in two forms. a)partly as free alkali and b)partly as chemically combined with collagen. Now that their utility is served, they should be removed. Free alkali which is soluble in water is removed partially bywashing the pelts in water. After washing, chemically combined alkali is removed by neutralising it with acids, acid salts, ammonium slats or substances with acidic reaction.

A number of chemicals are available for this prupose. The most commonly used are:

• Acids:
• Hydrochloric acid
• Sulphuric Acid
• Formic Acid
• Acetic Acid
• Lactic Acid
• Boric Acid
• Naphthalene sulphonic acid
• Acid salts:
• Sodium bisulphate
• Sodium bisulphate
• Ammonium Salts:
• Ammonium Chloride
• Ammonium Sulphate

Strong acids like hydrochloric and sulphuric rarely used. They are applied, if at all, in a vert diluted form. In a concentrated form they swell the grain and produce cracky leather. While using these deliming agents the amount applied should be such that the pH of deliming bath does not fall below 5, since acid swelling can occur which produces coarse and cracky grain. Among the acids, formic and lactic acids are generally used for deliming as they are very weak and do not swell the grain of the pelt to any appreciable extent.

Ammonium sulphate and ammonium chloride are most regularly used as deliming agents. Of these two, ammonium sulphate is considered to be better, since in neutralising lime, calcium sulphate formed gives some filling action. When ammonium chloride is used, calcium chloride is formed which has some solvent action on hide protein, making the leather poorer in substance and inferor in quality.