Stain removal is a vexing problem for many. There are hundreds of stains, and removing them, no matter how it is done, is a chemical process. Some stains are far easier to remove than others because of the chemical properties of the actual material that causes or creates the stain.
There are two primary categories of stains: organic and inorganic. I'll bet you wish you would have paid attention during your high school chemistry class! Organic stains are ones that are caused by things that appear naturally in our world. Examples of those would be tomato, beet, and grape-juice stains, pet stains, grass or other vegetation stains, etc. Any food stain or natural juice stain would be considered organic. These stains are usually not too tough to remove if you understand the chemistry.
Inorganic stains would be those created by things like permanent markers, paints, wood stains, etc. These stains are often much harder to remove from items because their chemical properties and the things that are associated with the stains are usually very likely to stick tenaciously to things.
If you have ever looked closely at the components of Velcro®, you should quickly understand why it works so well. The small stiff hooks of the one part lock themselves deeply into the fuzzy part. Stains are not much different. If you could look at certain stain molecules, they would resemble briars in that they have needles and sharp aspects that allow them to grab onto other objects that have openings.
Traditional soaps would try to encapsulate these stain molecules and lift them away from the object. But some soaps just can't move these sticky stain molecules.
Traditional chlorine bleach removes stains because it blasts apart the actual stain molecule. Chlorine bleach is a powerful oxidizing chemical that will look for the weak part of a molecule and crack it in two. The trouble is, it is indiscriminate. The chlorine bleach is like a napalm attack. It wipes out everything. It not only attacks the stain molecules, but it goes after any fabric or inorganic dye molecules as well. This is why clothing that is washed regularly in chlorine bleach falls apart over time. It is the same reason why bluejeans fade or get white spots on them if you drip chlorine bleach directly on the fabric.
Oxygen bleach, on the other hand, will remove organic and some inorganic stains, but is almost always fabric and color-safe. It is simply not as destructive as chlorine bleach.
