PHOTO BY DAVID HANSON

So, three years ago, when I first heard on radio about a product--called Clean Shower--that could relieve me of this unpleasant chore, I checked it out immediately. I wasn't disappointed. In my view, Clean Shower and products like it are the best thing to appear on grocery shelves since sliced bread. I stock up when these products are on sale; I clip coupons for them; my bathrooms are never without them.

Shower cleaners come in spray plastic bottles. Drying and cleaning after a shower is as easy as applying a few squirts of the pleasantly scented solution on the still-wet shower walls, shower curtain, and tub. I even use it on bathroom sinks. As long as a shower is reasonably clean to begin with, continuous use of these products will keep the shower clean.

Clean Shower was invented in Jacksonville, Fla., by a chemist named Robert H. Black. According to news accounts in 1997, Black was motivated by a life-changing event: His wife made him clean the shower, and he realized what a nasty job that was. "Being an inventor, I invented my way out of it," he is quoted as saying.

According to U.S. patent 5,910,474, the principal ingredients of Clean Shower are a nonionic surfactant, a chelating agent, and an alcohol. A preferred formulation described in the patent specifies the following composition, in percent by volume: isopropyl alcohol, 4.4; Antarox BL-225 (a mixed ethylene glycol ether  *  * nonionic surfactant), 1.5; Hamp-ene diammonium EDTA (a chelating agent that is a 44% aqueous solution of diammonium ethylenediamine tetraacetate), 1.5; and fragrance, 0.002. The balance is made up with water. The composition is supposed to prevent the buildup of deposits and provide a pleasant sheen on shower surfaces without the need for rinsing, wiping, or scrubbing.

The effect is immediately visible. Soon after a wet surface is sprayed, separate droplets of water coalesce into a sheet and glide down the surface. Within minutes, the sprayed areas are dry.

The surfactant breaks the surface tension of water droplets, flattening them and allowing the water to run down in the form of a sheet. The phenomenon is called sheeting action. Those droplets contain soap scum; oils and debris from the body; and salts of calcium, magnesium, or iron. If allowed to dry on their own, the droplets will leave residues that would build up over time. The chelating agent sequesters the ions of these salts, rendering them soluble. The alcohol helps to dissolve all the ingredients in water and to remove oily human debris.

COMPLETE REMOVAL of residues that could build up is impossible. Some residues will not reach the drain. Those will be trapped in the thin film that is left behind by the sheeting action. At the same time, the thin film also contains a bit of the surfactant and a bit of the chelating agent, which create a barrier against new residues. The next time the shower is used, the water rinses off the film and the residues therein. The shower gets cleaned every time it is used.

Clean Shower originally was produced by Clean Shower LP, Jacksonville, and was introduced to the local market in 1995. A marketing campaign that featured testimonials from disc jockeys and radio personalities, such as the talk-show host Rush Limbaugh, propelled Clean Shower to the national scene in 1998. In November 1999, the product was acquired by Church & Dwight, Princeton, N.J., which now sells Clean Shower under the Arm & Hammer trademark.

For a brief period, Clean Shower was the only product of its kind on supermarket shelves. But success quickly breeds imitation, and by mid-1998, it was competing with other shower cleaners for shelf space--Fresh Shower, Mist Away, and Shower Shine, for example. Annual retail sales of these products in the U.S. have reached $70 million.

Having tried all the brands available in my local supermarket, I know they are different from the original. None smells like Clean Shower. Some leave visible streaks on my shower walls.

Those products have entirely different formulations, says Ray Brown, director of R&D for household deodorizers at Church & Dwight. "There are ways to formulate and get similar results and not infringe on patents."

Clean Shower is about the special combination of a chelating agent and sheeting action that leaves a film with low residue, Brown says. "One competitor may be more concerned with leaving zero residue. So they leave out the chelating agent and base their product on having good sheeting action and nothing else. Another competitor may be working in a different pH range, which we think is not as effective as the pH range we use, but it works. Another one may use a different surfactant."

Ever since I've used Clean Shower and similar products, I have not had to deal with mildew in the shower. The absence of mildew, I thought, was due to rapid drying of surfaces when sprayed with these products.

That's only part of the reason for mildew-free surfaces, according to Brown. "The shower is never really dry," he says. "Tile grout typically holds water long enough for mold and mildew to grow. If you can keep the shower really dry, that will stop the growth of mold and mildew."

In fact, the formulation contains an active ingredient that prevents the growth of mold and mildew. But Church & Dwight cannot advertise that fact until it has completed an Environmental Protection Agency registration of the product as a disinfectant or a microbicide. "We are in the process of doing that," Brown says.

Chemical & Engineering News
Copyright © 2001 American Chemical Society