Background of Study
A soap is a salt of a compound, known as a fatty acid. A soap molecule has a long hydrocarbon chain with a carboxylic acid group on one end, which has ionic bond with metal ion, usually sodium or potassium. The hydrocarbon end is non polar which is highly soluble in non polar substances and the ionic end is soluble in water. The structure of the soap molecule is represented below:
The cleaning action of soaps because of their ability to emulsify or disperse water-insoluble materials and hold them in the suspension of water. This ability is seen from the molecular structure of soaps. When soap is added to water that contains oil or other water-insoluble materials, the soap or detergent molecules surround the oil droplets. The oil is, dissolved in the alkyl groups of the soap molecules while the ionic end allows it to be dissolved in water. As a result, the oil droplets are to be dispersed throughout the water and can be washed away.
A number of things affect the soap-making process and the quality of this soap produced. The characteristics of this soap depend on the quality of oil, and the amounts of the caustic soda and water used to make it. The speed of the reaction between the oil and the caustic soda is influenced by free fatty acid content of the oil, the heat of the components before mixing, and how vigorously the mixing is to be done. Free fatty acid contents, vigorous mixing, and heat, speed up the given soap-making process.
Castile soap: a mild soap originally made in Spain with pure olive oil. Today many “castile” soaps are made with other vegetable oils. Castile is agood cleanser, producing a rich lather.
Cream soaps: soaps containing cold cream materials, and moisturizers. Cream soaps are good for dry and delicate skin
Deodorant soap are soaps to which antibacterial agents have been added to reduce odor-causing bacteria.
Floating soaps: soaps which have air bubbles incorporated have low density. This causes the bar to float.
Hypo-allergenic soaps: Mild formula soaps, low in potent irritants. They generally produce a poor lather.
Milled soaps: these are the most commonly used, mass produced soaps. Milling is referred to the mixing of colour and soap flakes.
Oatmeal soap: A rough textured soap to which oatmeal has been added as a mild abrasive and lather. Good for and normal skin.