Bleaches

Bleaches make white things even whiter. There are chlorine bleaches and all-fabric bleaches. Chlorine bleaches contain 4.25% sodium hypochloride solution (NaOCl). In some bleaches the chlorine hits the fabric all at once and can damange some fabrics if direct contact is made. The active ingredient in chlorine bleaches is the hypochloride ion (ClO2-). These bleaches work because they remove loosely-bound electrons which color fabrics. These loosely-bound electrons can color or dull fabrics because they have the ability to absorb visible light as they move to higher energy levels. The absorption of visible light causes the dulling effect. By immobilizing or removing these electrons, the chlorine bleach makes whites look whiter. Chlorine bleach works well on cotton and linen fabrics.

Another type of bleaching agent is composed of the hydantoin and cyanurate bleaches. These bleaches release chlorine slowly in water. A lower concentration of chlorine is less damaging to the fabric.

A third type of bleaching agent is the oxygen-releasing bleach. Sodium perborate, a builder releases hyrdogen peroxide, which acts as a bleach. Oxygen bleaches aren't active chlorine bleaches but they are better for bleaching synthetic fibres. You need to use more bleach, hotter water and a more alkaline solution with these than with chlorine bleach, but they do work well when used properly.

Borax, also known as sodium pyroborate, Na2B4O7, is often added to oxygen-releasing bleaches because of its ability to clean. Its pH is about 9.5, so it produces an alkaline solution which make the all-fabric bleaches work better.