RIO DE JANEIRO - Electrical tape on private parts. Really?

Welcome to the latest fashion fad in beauty-obsessed Rio de Janeiro, where some women are sun-baking in bikinis made of black tape in search of tan lines so perfect that they practically jump off the skin.

"Here's where you get the white tan lines that make all the women jealous," said Alexandra da Silva Prazeres, tanning with about 20 other women at Erika Bronze salon, one of several using the technique in Rio.

It works like this. First, a piece of gauze is placed over a woman's private parts. Next go the strips of electrical tape to mimic a bikini. Then small pieces of wet paper towels are placed over parts of the tape. Using sticky tape instead of a cloth bikini ensures crisp lines that stay just so.

Holding black electrical tape and scissors, beauty salon owner Erika Martins instructed a woman to stay still while she carefully placed tape between her buttocks where the bikini would have gone. After a few more strips, the young woman was ready to bake, Rio style.

While pulling it off would normally hurt, temperatures close to 100 degrees Fahrenheit (40 Celsius) ensure plenty of sweat and a smooth removal.

"You must have a lot of determination because it's tough," said 36-year-old sunbather Miriam Rodrigues of the heat. "But we can handle it."Martins said she decided to start the salon after years of experimenting with the technique on herself and friends. She said in working-class neighborhoods women often use similar techniques, as they are far from the beaches.

Today, Martins' rooftop fits 30 women and is at full capacity seven days a week, as long as the sun is out. Her Facebook page has 68,000 followers.

Clients must book and pay about $20 in advance to guarantee a spot on one of her terrace lounges.

"My skin doesn't tan easily," said Hellen Marinho, who is of African descent. "I saw her doing a dark skinned girl and I liked it and decided to try."Sunscreen is applied to the exposed skin, followed by a special tanning lotion sold at the salon.

Tanners who don't want sunblock or want to stay out longer than recommended must sign a disclaimer absolving the salon of liability.

Depending on the sun's intensity and the customer's skin color, Martins has them lay belly up for around an hour, and then belly down for the same amount of time.

Dermatologists are more horrified than impressed with the technique, which they say can increase the chance of getting skin cancers, including melanoma. They say that applying sunblock before tanning lotion is useless.

It is "like trying to put out a fire by throwing water on it while at the same time adding fuel," said Dr. Egon Daxbacher, president of the Brazilian Dermatologist Society of Rio de Janeiro.

Despite being sprinkled with water, some tanners feel dizzy or even faint after a rooftop session.

Still, when it's over, women peel off their tape bikinis and marvel.

"We look sexier, it boosts our ego, and it looks prettier," said 22-year-old Milena Carvalho. "It's the Brazilian woman's trademark."