Fat and alkali are the two primary raw materials needed to manufacture soap. Depending on the intended application of the soap, sodium hydroxide or potassium hydroxide is generally used as an alkali.
If potassium hydroxide is used, it produces a more water-soluble product than its sodium-based counterpart, and is thus often called “soft soap”.
In the early days, raw animal fat (tallow) obtained from slaughterhouses was used directly, but modern-day soap manufacturing processes mostly involve the use of processed fat. In this way, many impurities are eliminated.
Many vegetable fats like palm oil, olive oil, coconut oil etc. are also being used in soap manufacturing.
To enrich the colour and texture of the soap, additives are often used. Similarly, to supplant the foul odour generated through the manufacturing of soap, perfumes and fragrances are added to the soap mixture.