Information For Ingrid

By Nathan Schiff, Ph.D.
Associate Editor - Institutional, FABRICARE

Dear Dr. Schiff:
I am in charge of ordering supplies for our nursing home. I have enjoyed
your articles in Fabricare, and hope you can help me. My problem is that
soap salesmen talk over my head. They use words like surfactants,
saponification, alkaline builders, polymers, brighteners and sours in
talking about their products. I want to buy the best products, but I don’t
understand what these things mean.
Can you help me?

Ingrid S.

Dear Ingrid,

Before I get into specifics, I would like to mention one very important matter you should take into account in choosing a soap supplier. This is technical support. You should ask the salesman if the company has a chemist on staff who can provide help when problems arise. The technical support which a supplier can provide is very important. Resource people who understand your specific needs can keep you out of trouble and make your laundry function efficiently.

Surfactants
The word surfactant is an abbreviation for surface-active agent. If you gently place a stainless steel razor blade on the surface of a tub of water, it will float. Water has an invisible but relatively strong surface. Add a few drops of a surfactant, such as soap, to the water, and the floating blade sinks. The surfactant reduces the surface tension of the water to a point where it can no longer support the weight of the blade.

What does this have to do with detergency? To be completely effective, a laundry detergent must lower this surface tension so that it can come into contact with the soil on the fabric, like the razor blade sinking in the water. So the job of a surfactant is to lower the surface tension of the water in order to increase the penetration of chemicals into fabrics. Surfactants also perform the job of dissolving some oil-based food stains. They do this by breaking them into smaller fragments. This makes it easier for the particles of the stain to remain suspended in water and to react rapidly with other chemicals in the detergent.

Saponification -An Ancient Discovery
The early Egyptians are credited with discovering what we call "saponification". They discovered that melted animal fat which had ashes from a fire mixed into it could be used to remove soil from clothes. This crude soap (saponification) produced cleaner linens with less effort than water alone. The ashes converted insoluble oily stains into water-soluble residues, which could easily be rinsed away.

Alkaline Builders
When someone speaks of an alkaline builder, it is a chemical which performs much the same function as the ashes in the fat did in ancient times. It is added to detergents to increase the efficiency of the surfactant (the chemical which reduces the surfac tension of the water). Builders perform several functions including breaking up soil into fragments small enough to remain suspended in water so they are not deposited back onto fabrics. They also help to soften hard water and prevent corrosion in the metal parts of washers. They may be listed on a label as silicates or carbonates. Phosphates, which are allowed only in some areas, are also builders.

Polymers
It is the job of polymers to prevent the transfer of dye from one fabric to another. Polymers capture loose dye and hold it in suspension in the water. These dyes bond strongly with polymers and are thus kept from transferring onto fabrics in the wash load.

Brighteners - Also Called Optional Brighteners
Natural fibers such as cotton, linen and wool tend to turn yellowish with age. This is an irreversible biological process which can be covered up by the use of optical brighteners. They reflect blue light, reducing the perception of yellowing and giving an illusion of brightness to the garment.

Sours
When a load has been thoroughly rinsed, a small amount of residual alkalinity remains on the fabrics. This often results in giving fabrics a harsh feel. If not neutralized it may also cause skin irritation. To prevent this, an acidic rinse is used to neutralize the alkalinity. Before today’s sophisticated hair care products were available, women often used vinegar (a mild acid) as a final rinse after shampooing. Just as sour gives a better feeling to fabrics, the vinegar made hair feel silkier. Your soap salesman may refer to this process as souring down.

In Conclusion
Ingrid, I have just scratched the surface of what goes on in that laundry department of yours. But I hope I have given you help in dealing with salesmen who use strange words. In future articles I will explain hard water and how to deal with it, and give you a more complete explanation of alkalinity. I will also tell you about some of the other chemicals which help make modern detergents the remarkable products they are.

Class dismissed, until next article.