- Why are there oil spots on freshly dried clothes?
- Why does ordinary shampoo sometimes clean better?
- What is Soap?
- What is Detergent?
- What is the difference between a Soap and a detergent
The first question is probably about the spots caused by fabric softener, and I’ve come across info about that in your Fabric Care article. That article attributes the spots to the softener sheets, but I first encountered the spots on polyester garments in the days when I used liquid softener in my washer. Re-washing always removed them. See (Q) and (A) below.
As for the last three, shampoo contains our friend sodium lauryl sulfate. The soap/detergent question would be answered by the post that I agreed to send you. A major revision of it is below. (Thanks for bringing that to the top of my “to do” list; I should’ve answered long before now.)
Questions & Answers for Soaps & Detergents
(Q) Why are there oil spots on freshly dried clothes?
(A) Fabric softeners, both liquid and dryer sheets, can leave greasy spots on polyester garments. The spots can be removed by re-washing and drying without the softener. See the article Fabric Care
(Q) Why does ordinary shampoo sometimes clean better?
(A) Shampoos contain detergents which are are especially good cleaners of substances which are proteins. Hair, silk and wool are all proteins. See “Soaps and Detergents” below.
(Q) What is Soap?
(A) Soaps are FATTY ACID SALTS made by a reaction of fats (an animal fat or a vegetable oil) with LYE (sodium hydroxide). SODIUM LAURATE, the sodium salt of lauric acid, is generally considered to be one of the finest soaps.
(Q) What is Detergent?
(A) Detergent is a chemical compound that cleans. In the sense that a SOAP cleans things, it can be considered a detergent. However, chemists generally make a distinction between soaps and detergents, since soaps are salts of carboxylic acids, and detergents are sulfate or sulfonate salts.
SOAPS AND DETERGENTS
DETERGENT
Detergent is a chemical compound that cleans. In the sense that a SOAP cleans things, it can be considered a detergent. However, chemists generally make a distinction between soaps and detergents, since soaps are salts of carboxylic acids, and detergents are sulfate or sulfonate salts.
SOAP
Soaps are FATTY ACID SALTS made by a reaction of fats (an animal fat or a vegetable oil) with LYE (sodium hydroxide). SODIUM LAURATE, the sodium salt of lauric acid, is generally considered to be one of the finest soaps.
HARD WATER (water containing the dissolved salts of calcium, magnesium and/or iron) causes a problem: the dissolved salts combine with soap molecules to produce a water-insoluble scum (“ring-around-the-tub”). A lot of soap is wasted in the formation of this scum, as all of the minerals in the water have to be removed as scum before the soap can do its cleaning work.One solution to this problem is to wash only with distilled water, which contains no salts. This is not usually practical.
DETERGENTS
Our modern technological solution (since the 1940s) to the soap scum problem is to use SYNTHETIC DETERGENTS which don’t precipitate the mineral salts found in hard water. Some of these synthetic detergents are chemically related to soaps, as they are derived from the same fatty acids used to make soaps. SODIUM LAURYL SULFATE (derived from the fatty acid lauric acid by a series of chemical reactions) is such a detergent. It can be found in _many_ common household products. Sodium lauryl sulfate belongs to a class of detergents referred to as “anionic.” These compounds are especially effective at cleaning fabrics that absorb water readily, such as those made of NATURAL FIBERS, such as COTTON, WOOL AND SILK.
ORVUS is a commercial name for sodium lauryl sulfate. It is available at feed stores, which sell it as a shampoo for the manes and tails of show animals. Sodium lauryl sulfate is also packaged as a quilt soap and can be found at suppliers of quilting products.
Sodium lauryl sulfate is a common ingredient of SHAMPOOS, and some persons like to use shampoo for handwashing natural fibers. However, you should be aware that shampoos may contain additional compounds which could cause undesirable results if used for laundering fabric.
Read product labels! In the USA, ingredients are listed on labels in order of decreasing quantities. If you use a shampoo for washing natural fibers, you want to find ingredients that contain the chemical prefix “laur” (from lauric acid). Myristic acid, palmitic acid, and stearic acid are also produced from fats by the action of lye, and are considered excellent soaps. Like lauric acid, they are converted into anionic detergents; therefore, you might also find the forms “myris,” “palm,” and “stear” among the ingredients.
The usual granular laundry detergents are sodium salts of fatty derivatives of aromatic sulfonic acids. They are of the anionic class, with similar cleaning properties to those of sodium lauryl sulfate. Manufacturers have now solved the problems with biodegradability which originally plagued these types of synthetic detergents.
Another class of detergents is referred to as “nonanionic.” These are especially good for cleaning synthetic fabrics, such as polyesters. Most are liquids and produce little foam. You’ll find them (along with anionic detergents) in dishwashing liquids and liquid laundry detergents. The “cationic” detergents, as well as being cleaners, also happen to be effective germicides and are used in antiseptic soaps and mouthwashes. They’re also used in fabric softeners because their positive charges (cations) adhere to many fabrics that normally carry negative electrical charges (anions).
In conclusion, it needs to be emphasized that no one cleaning product is best for everything because of the chemical properties of the fabric being cleaned, and the chemical properties of the detergent.
By: Virginia Caine
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