Sick of curls? Dread what summer humidity does to your hair?

You may be a candidate for thermal reconditioning, a hair-straightening process developed in Japan.

While there are different straightening systems--Liscio and Yuko are the most popular--the process works the same way. The hair is washed, coated with chemicals, washed again, blown out, ironed stick-straight, and treated with a neutralizer. The chemicals break down the bonds in hair, leaving it straight and immune to frizz.

The process can take up to eight hours. The results last until your hair grows out, usually six to nine months before a touchup is needed. Prices average $400 to $600.

After actresses such as Julianne Moore and Jennifer Lopez jumped on the straightening bandwagon, many women flocked to salons to have it done.

To read about two different results--why one woman loves her straightened hair, why one would never do it again--see the following pages.

Thermal straightening is tricky to do. "It is probably the hardest thing I've learned to do since I've been a hairdresser," says Dennis Roche of Roche Salon, a 33-year veteran of the hair industry.

If you're considering thermal reconditioning, go for a consultation first. Vincent J, one of the country's leading experts--he's straightened 4,000 heads in the past five years at his Fort Lauderdale salon--suggests asking these questions:

• What training has the stylist had? Vincent J, as he's known, says to look for someone who has taken a seminar on thermal reconditioning and continues to take advanced courses. Stylists trained by Liscio or Yuko seem to be best. The actual training may not be as important as the number of heads a stylist has done. "The longer you do it, the better you get," says Diego Paez of Art & Chemistry in Rockville. Look for someone who's straightened at least 100 heads.

• Ask if assistants will be working on your hair, in what capacity, and how they've been trained. While assistants can save time, problems often arise if assistants without much training are given too much responsibility. Some salons, like the Watergate, do not use assistants.

• Touchups are trickier because stylists need to protect already-straightened hair. "You don't want to overlap new relaxer into the old," Paez says. Find out what steps a stylist takes to protect your hair, and make sure he has done touchups before.

• Know what you're getting. Diana Inlow of Headliners salon in McLean suggests looking at a stylist's before-and-after pictures. Ask what maintenance your hair will require afterward. Liscio and Yuko mean minimal blow-drying daily; other processes might require more care. The new straightening alternative, also called "mini thermal reconditioning" or "curl reducer," is cheaper, takes less time, and gets rid of frizz--but it won't make hair stick-straight.

• Find out the redo policy. Even good salons can leave wavy spots. Many fix a problem area for free, but some charge. Paez says that thermal-reconditioning companies guarantee only that 80 to 100 percent of hair will be straightened--some hair doesn't straighten as well. Virgin hair, or hair that has never been permed or color-processed, is often more resistant.

• Mention other treatments you've had. Your stylist should ask if your hair has relaxers or color in it, and you should tell him about any process done within the past four years. Protectants can be put on the hair prior to the procedure to avoid damage. If your hair is unhealthy or has been extensively colored or treated, or if the process isn't done correctly, hair loss and breakage can occur.

Giving It to You Straight

These salons were rec-ommended for thermal straightening by Vincent J, by readers, and on message boards such as lamasbeauty.com/talk/salon. Prices we quote for thermal reconditioning are starting figures. You may pay more if your hair is longer or curlier.

Aqua Hair and Skin Care, 1513 Wisconsin Ave., NW; 202-337-3477. Starts at $650, straightening alternative at $175.

Art & Chemistry, 5224 Nicholson La., Rockville; 301-468-6900. Starts at $500, alternative at $250.

David's Beautiful People, 12121 Rockville Pike, Rockville; 301-881-2540; davidsbeautifulpeople.com. Starts at $500.

Eclips Salon, 44110 Ashburn Village Plaza, Ashburn, 703-858-7555; 6661 Old Dominion Dr., McLean, 703-821-0022; eclipshair.com. Starts at $550.

Headliners, 6744 Old McLean Village Dr., McLean; 703-356-1100. Starts at $450, alternative at $150.

O Salon, 1079 Wisconsin Ave., NW; 202-338-9100; osalon.com. Starts at $650, alternative at $185.

Piaf Salon, 1023 15th St., NW; 202-783-3334; piafsalon.net. Starts at $400.

Roche Salon, 3050 K St., NW; 202-775-0775; rochesalon.com. Starts at $500, alternative at $250.

Watergate Salon, 2532 Virginia Ave., NW; 202-333-3488; watergatesalon.com. Starts at $700.

Many straight-hair addicts head to Florida or New York to go to salons that specialize in thermal reconditioning. A round-trip train ticket to New York and straightening at Hayato, one of the top thermal-reconditioning salons in the country, comes to $490--versus $700 at the Watergate Salon in Washington.

These are salons worth trying outside of Washington:

Gil Ferrer, 21 E. 74th St.; 212-535-3543; gilferrersalon.com. Starts at $500.

Hayato, 125 E. 23rd St.; 212-673-7373; hayato-ny.com. Starts at $200.

Hidy Hair, 34 W. 32nd St., 212-279-9393; 2033 Lemoine Ave., Fort Lee, NJ, 201-242-9099; hidyhair.com. Starts at $500.

John Frieda, 797 Madison Ave., 212-879-1000; 30 E. 76th St., 212-327-3400; johnfrieda.com. Starts at $600, alternative about $350.

Vincent J Salon, 3301 NE 33rd St., Fort Lauderdale; 954-566-6601; vincentj.com. Starts at $600, alternative at $300.