Soap Versus Detergent

Soap Versus Detergent

As a manufacturer of products to care for clothing, footwear, and outdoor gear, I am frequently asked about the difference between soap and detergent. I’m going to try to keep this as simple and general as possible so that it applies to cleaners from laundry detergents to baby shampoo. You can also look up the Soap and Detergent Association’s online info to see what they have to say. Remember, these folks are marketers for their industry and though their information is accurate, it may not be complete.

The FDA has a definition to distinguish soaps and detergents for the purpose of applying regulations. It gives special treatment to alkali salts of fatty acids. In fact, soap is just a very unspecial form of detergent. 100 years ago there was no such thing as detergent but almost every cleaning aid we had, especially everything called soap, is now under the definition of detergent. When someone says a cleaning product is a “Soap - Not a Detergent” or it is a “Non-Detergent” they are just marketing statements.

A detergent is anything that grabs onto dirt, soil, grease, oil, odor, etc. and holds it well enough to loosen its grip on clothing, skin, hair, house paint, etc. and pull it into the wash water. This gets tricky. If the detergent hooks-up too well it may join the dirt on the fabric or surface and become part of the problem (soap and detergent scum). So our cleaning agent must remain well attached to the water so that as the water rinses away, the detergent goes with it still holding fast to the dirts and soils it has released from the material being cleaned.

That’s how cleaning works whether we call it soap or call it detergent. The difference comes from how we create the cleaner that must love oily dirt on one hand and love water on the other hand. A detergent or soap molecule is different on one end from the other. One end loves dirt and the other loves water.

A modern chemical plant can make any kind of cleaner you want. There are many compounds that are non-polar or uncharged at one end and polar or charged at the other end. The non-polar end will grab the dirt from the surface and the polar end will hang onto the wash water to carry it all away. You can make each molecule exactly the same for a very specific dirt or you can create blends of several different molecules to attack a range of soils. Each of these elegantly engineered molecules is a surfactant (surface active agent) and a blend of surfactants for a specific cleaning task is a modern detergent. The value, effectiveness, safety, efficiency, biodegradability and purity of a proper detergent is a work of art.

Unfortunately, modern marketing is not overly concerned with great cleaning, so they add brighteners, softeners, colors, anti-microbials, fragrances, enzymes, extracts, essential oils, vitamins, milk, tea, oatmeal, etc. The list goes on forever, a long march of “new and improved” products to eager consumers. Manufacturers can produce outstanding detergents but Marketers insist on polluting them all with counterproductive chemical slop.

Is “Soap” the answer? NO, quite the contrary! Most of them are based on the modern surfactant blends, same as the products called detergents. Soaps usually have all the same modern pollutants that you find in detergents and they have the additional problem of not working well in hard water.

There are some “Soaps” that don’t use efficient surfactants. They use fats or oils that have had a charged group of atoms attached by ancient chemistry. If they actually do the cleaning with an alkali salt of fatty acid, they meet the FDA definition of Soap.

The classic form is to boil animal fat and throw in an amount of lye that will supply charged ends for all the oil molecules. You have very little control of this process. It’s more art than science. You are beginning with a mix of different fat/oil molecules and a mix of alkali along with impurities. Time and temperature cause various combinations to occur and each will interact differently with the soils and especially with the calcium and magnesium in the wash water. Such soap doesn’t clean well and often leaves a bigger mess than you started with, particularly in hard water. Now add peppermint, honey, apricot extract and a dozen more sensitizers and you have a toxic mess guaranteed to succeed in a market where products strive to distinguish themselves by the chemical residue they deposit on your hair, skin and clothing.

So how do you choose a cleaner?

For starters, forget about looking for “Soap”. It’s probably not really Soap and would be a poor choice if it was.

What ingredients should we look for and which to avoid? This is a trick question. It’s not what is in the cleaner that causes problems, it’s what fails to rinse off your skin, your hair and your clothes. A properly selected high quality surfactant should do the job efficiently and rinse away completely. A proper blend of two or three compatible surfactants can be the basis of a good cleaner. Rather than name hundreds of possible ingredients that may or may not be synergistic or appropriate, my advice is to find a product that does the best job with the least ingredients in number and amount.

Liquid laundry detergents should do a machine load with one ounce or less. A laundry powder should dissolve to totally clear in cold water in one minute or less and should get the job done with one tablespoon per wash load. If more is required, there are several possibilities and none of them beneficial except to the marketers. They may just water it down so you think you’re getting more for your money. This is a waste of packaging, space, transport, convenience, etc. Maybe they use poorly chosen, incompatible, inappropriate, or ineffective surfactants and need lots more chemical to do the job. Usually they have loaded in so many counterproductive chemicals to “Distinguish” their product that it overwhelms the cleaners so they have to use more. This a recipe for poor rinsability and lots of irritating residue.

And how do you measure performance? Assuming it removes obvious soils and odors, here are a few other things to look for.

If a product leaves UV Brighteners or Fluorescent Whitening Agent, it’s not clean.

If a product leaves an antimicrobial, it’s not clean.

If a product leaves a residue that reduces water repellency, it’s not clean.

If a product increases flammability of 100% Polyester, it’s not clean.

If a product adds to the weight of the fabric, it’s not clean.

If you need to use fabric softener, it’s not clean.

If your hair feels cleaner for a few days each time you switch brands, it’s not clean.
A product should be “Readily” Biodegradable and economical enough so that you can use it for the rest of your life.

If you have very soft water and very little dirt or odor, a soap can do a fair job on common soil. If, however, you have special fabric, soils, odors, skin sensitivities, or high tech features to restore and maintain, only detergents can do the job. The real villain is the residues of fad ingredients that can be added to both soaps and detergents.

You can eliminate all residues and the odor, performance, and irritation issues they cause by selecting Sport-Wash Residue-Free Detergent or Sensi-Clean Irritation-Free Detergent from Atsko/Sno-Seal.

For personal care, choose Sport-Wash Hair & Body Soap or Sensi-Clean Shampoo & Body Gel. The Sport-Wash and Sensi-Clean Brands are the same product marketed to target the diverse demographics and issues that are addressed by eliminating residue.

For more information on HOW TO AVOID UNNECESSARY CHEMICAL EXPOSURE and to see UNIVERSITY TEST DATA on residue free detergents, visit The Illinois Institute of Technology (my Alma Mater) has a class room demonstration of soap making included on their website. You can get a sticky feeling for why soaps have been replaced by detergents here.