While using a petroleum product to “base,” to protect the scalp from a relaxer seems old-school, Carmine Minardi, co-owner of the Minardi Salon in New York City and the Beauty Focus seminars, says that the procedure does have a purpose in modern chemical services.

“When you’re using sodium hydroxide relaxers, basing allows you to keep the relaxer on the hair for as long as needed without causing chemical burns or irritation to the surrounding skin or scalp,” he says.

Minardi, who has taught classes in contemporary relaxing techniques for the past 15 years, says that he uses a petroleum product to shield the hairline, nape and ears of every chemical relaxer client. But whether he chooses to base depends largely on the client’s ethnicity.

For very curly-haired Caucasian clients, Minardi prefers the effectiveness of sodium hydroxide relaxers over the more traditional thioglycolate formulations, and these are the clients for whom he adjusts his technique.

“I've been using sodium hydroxide relaxers off-scalp, about a quarter of an inch away from the skin,” he says. Why? He wants the hair to retain a minute lift at the scalp to prevent it from looking unnaturally flat.

The bonus is that keeping the relaxer off the scalp enables him to avoid burning while allowing maximum development time for the desired results. “This gives me more control, instead of having the scalp dictate when the product must be removed,” he says.

On his African-American clients, Minardi gets closer to the scalp, an eighth of an inch nearer. “These clients may be accustomed to having a relaxer done right to the scalp, for maximum benefit and flatness,” he says. “For them, it is essential that you base each and every part of the scalp.”

Approach basing as meticulously as you do relaxer application, Minardi advises. “Petroleum basing can create problems if it is applied in a sloppy or thick manner,” he says. “You run the risk of some of the protection getting on the hair that needs to be relaxed and the results may be uneven because the relaxer will not alter the protected hair.”

Finally, Minardi recommends doing a close read of relaxer instructions. “A proliferation of ‘non-hydroxide’ relaxers have been introduced over the past several years,” he says, “formulated with much lower levels of alkaline and many without sodium hydroxide. Basing may not be required because the product won’t have the strength to affect the scalp or skin.”

Bottom line: Read the label and do a strand test.

DOWNLOAD: Carmine Minardi's Relaxer Reference Chart.