How Laundry Detergent Works…
Soaps and detergents are made from long molecules that contain a head and tail. These molecules are called surfactants; the diagram below represents a surfactant molecule.
The head of the molecule is attracted to water (hydrophilic) and the tail is attracted to grease and dirt (hydrophobic). When the detergent molecules meet grease on clothes, the tails are drawn into the grease but the heads still sit in the water.
The attractive forces between the head groups and the water are so strong that the grease is lifted away from the surface. The blob of grease is now completely surrounded by detergent molecules and is broken into smaller pieces which are washed away by the water. You can find out more about how detergents work here.
The detergent molecules also help to make the washing process more effective by reducing the surface tension of the water. Surface tension is the force which helps a blob of water on a surface hold its shape and not spread out. The surfactant molecules of the detergent break apart these forces and make water behave, well, wetter!
See more here @ Science on Shelves
In short – soap grabs dirt and rinses it away
USE LESS DETERGENT! When you add lots of soap you are at the risk of it not fully rinsing out, in other words attracting more dirt to your clothes.
The Best Laundry Detergent…
Best Over All Laundry Detergent
CR’s take: Kirkland Signature Ultra Clean is about half the price of higher-scoring detergents from Persil and Tide. Kirkland cleaned up nicely in our tests, earning an Excellent rating in removing stains from body oil, one of the chemicals in sweat (think sweaty workout clothes). But Kirkland doesn’t pack the same punch when it comes to blood and grass stains, so consider the types of stains you typically have to contend with. And this is one of the handful of detergents tested that cleans well in hard water. If you are in Bemidji and want to pick some of this up try the Costco in Baxter or St Cloud. (Consumer reports article here)
Best Laundry Detergent for Sensitive Skin
CR’s take: Persil ProClean Power-Liquid for Sensitive Skin is the best of the detergents we tested that are marketed for sensitive skin at tackling grown-up stains like body oil, dirt, and salad dressing, snagging an Excellent rating in that test. But heads up: Detergents that are supposed to be free of dyes and perfumes may still have some scent from the chemicals used to make the formula.
Best All Purpose Laundry Detergent
Park Avenue Laundry’s Take: Dr. Bronner’s Pure-Castile Soap is the most versatile and environmentally friendly soap we have found. A bottle of this in your suitcase is like gold. Use it as a body wash, shampoo, dish and laundry detergent, and more. The link above will take you to their dilution chart for each use. Not only is it versatile, but it is biodegradable. This soap is safe in your washing machine and a water source like a river. In other words, you could bath in a lake with it, and it is safe. It comes in many different scents, including fragrance-free. Give it a chance; you won’t be disappointed.