Do more blades mean a better shave?

As anyone with a television knows, shaving razors are high-tech. Men’s razors have gone from one blade to six, and they feature vibrating blades, rubber fins to stretch the skin and gooey strips to reduce friction. The money involved in shaving is staggering. According to Forbes, Gillette’s 35 percent profit margin is the highest of any Procter & Gamble brand, and the personal grooming market for men and women combined is worth $14 billion in annual sales.

But a band of contrarians gathering at such websites as Badger and Blade and Reddit.com’s Wicked Edge claim that, for all the change in men’s razors, we’ve made no progress. They say that multi-blade razors — often touted in commercials for their ability to “lift and cut” the hair beneath the skin line — are a major cause of ingrown hairs. They also say that dragging six blades across the face causes more bumps and irritation than a single blade would.

The darling of these shaving contrarians is the double-edged safety razor: a handle attached to a metal guard that exposes just the edge of a simple, two-sided blade. Conspiracy theorists say big companies largely abandoned the model, which dominated men’s shaving throughout the early and mid 20th century, when they realized that making five-cent blades wasn’t a growth industry. Anyone could manufacture them at bargain basement prices. So “big shave” developed a patentable product for which it could command a premium without direct competition.

Let’s take a step back and examine the science of shaving. The first comprehensive academic paper on the topic I could find was published in the Journal of the American Medical Association in 1937, when two Pittsburgh scientists, Lester Hollander and Elbridge Casselman, conducted a delightful set of experiments. The researchers found, for example, that freshly cut hairs grow very quickly at first, before slowing to a rate of just under half an inch per month. Hairs seldom grow perpendicular to the face, but rather at an angle of 31 to 59 degrees. This can bedevil those seeking a close shave, because the hairs don’t stand up for cutting.

Hollander and Casselman noted that hair is composed largely of keratin, a substance that absorbs water easily, softening it and making it easier to cut through. The scientists weighted shafts of hair and submerged them in water, measuring how long it took for the hair to reach its maximum stretch. If warm, soapy water is used, it takes 2½ to three minutes to fully hydrate and soften a facial hair.

Shaving removes almost as much skin, by volume, as hair, according to the study. The scraping away of the outer layer of skin likely accounts for much of the discomfort of shaving, with the scientists arguing that stiffer shaving lather and shaving no more than once every two days ameliorated the effect.

All of Hollander and Casselman’s experiments were based on the safety razor, which was most Americans’ weapon of choice in the 1930s. Disposable cartridge razors didn’t become popular until the 1970s. By that time, shaving was big business, and almost all of the research on razors and hair removal was produced or funded by the industry itself.

Today, Gillette boasts a sophisticated shaving laboratory in Reading, England. The company tests its products on thousands of men, both in the lab and in the men’s homes. Testing periods run from six weeks to several months. The company’s researchers present study subjects with dozens of questions about comfort, irritation, safety and ergonomics. They have tools to measure skin hydration and imaging devices to detect tiny nicks and cuts. And what do they think about the arguments against multi-blade shavers?

“We have seen no circumstantial evidence that multi-blade razors lead to ingrown hairs,” says Kristina Vanoosthuyze, a research and development scientist for Gillette.

Advocates of the safety razor claim that it takes a week or more to learn how much force to use with the old-school device and the appropriate shaving angle, so I asked Vanoosthuyze if it’s possible that single-blade razors could be superior, if you take the time to learn the proper technique.

“Categorically, no,” she said. “Every time we add a blade, the comfort of the shave has improved.”

Vanoosthuyze offers several other tips from the Gillette labs.

Ÿ Part of the challenge for a razor is remaining flat against the skin, a decidedly non-flat surface. Dead skin and leftover trauma from prior shaves can create uneven pressure and expose some areas to excessive force from the razor. Scrubbing away as much of the dead skin and grime as possible prior to shaving is a good idea whatever kind of razor you use. (Hollander and Casselman made similar findings way back in 1937.)

Ÿ Ingrown hairs, which are painful, unsightly and can get infected, often occur when neck hairs emerge at acute angles and then re-enter the skin. In other cases, the hair gets trapped in extra skin around the follicle. If ingrown hairs are a problem, Gillette’s studies show that using a facial scrub can free trapped hairs, exposing them to the razor. (A 1979 study found that electric razors that leave hair slightly longer produce fewer ingrown hairs than manual razors.)

Vanoosthuyze says Gillette’s studies also show that, contrary to popular belief, men find shaving more comfortable and suffer from fewer ingrown hairs when they shave every day, rather than taking a day or two off between shaving sessions. Gillette’s claims that more shaving is better contradicts the conclusions of Hollander and Casselman, and it also plays into conspiracy theories of the pro-safety-razor crowd.

Gillette may have brought some of these doubts on itself. “Gillette has historically not done well with publishing research,” says Vanoosthuyze. She argues, however, that since Procter & Gamble acquired Gillette in 2005, the company has been more aggressive about disseminating its findings in peer-reviewed journals and presenting at dermatology conferences. (There have been some stumbles. Earlier this year, a study involving post-shave moisturizers by an independent researcher hired by Proctor and Gamble included several paragraphs taken verbatim from an earlier publication attributed to Proctor and Gamble scientists.)

In the end, the debate over which is the best shaving device may come down to the tremendous variations in the way men wield their razors.

“Some people shave in 30 seconds; others take 25 minutes,” says Vanoosthuyze. “Some use 700 strokes, some 30 strokes. Some people apply 50 grams of force, others 1.5 to two kilos of force per razor stroke.”

This may simply be an area in which you have to do your own research.