When you're slathering on your sunscreen this summer, don't forget to protect your ringlets.

Unlike skin, hair will not become red and painful when it becomes overexposed to the sun so it's more difficult to measure UV protection in hair. But UV exposure can sap the hair of strength and elasticity and cause photo-oxidation, which triggers discoloration and fading in both natural and color-treated hair. According to a study by the Rene Furterer Research Center, after just three days of sun exposure, the scale-like cells that cover each individual hair shaft begin to pull off, making the hair dry, dull and brittle.

"Hair does not get sunburned," says Stephanie Sprankle, manager of education and development for Redken. "But it will fade. If you put a couch in front of a window, the side against the window becomes really faded. It's the same with the hair. You don't want to spend all that money coloring your hair and have it wash away."

A growing awareness of the sun's damaging rays along with technological advances in the hair-care industry have led to a boom in the number of summer hair products this year -- products with names like Sun Bandana, Swim Cap, Sun Veil and Canopy. These products are designed to protect the hair during summertime activities like swimming and sunning, as they moisturize and repair parched locks.

In addition to products specifically designed for use in the summer conditions, such as Hamadi's Shea Spray, a growing number of companies are adding UV protection to their products. Color-treated hair, especially, been treated to a robust selection of UV-protectant products: Paul Mitchell Color Protect Locking Spray, Aveda Color Conserve Sun Protector and Pureology UV Colour Defense.

Summer Hair Care Tips

- Always protect hair when in the sun. - Use a UV protection product, a hat or scarf. - Reapply UV protection throughout the day. - Wear a swim cap. - Use a deep conditioner once a week. - Wet hair before going into a pool. - Rinse hair well after swimming. - Limit shampooing to once or twice a week.

Unlike skin products, hair products typically are not rated on their sun protection factor (SPF). But the UV filters in hair products protect against the same things as skin products -- UVA and UVB rays, Volpi says Jennifer Volpi, senior manager of marketing for Biolage. Rene Furterer has created a KPF (keratin protection factor) protection measurement rating for its Sun products, the first hair protection rating system. L'Anza Swim & Sun line uses the HPF (hair protection factor) measurement system for its products.

Hair can be best protected from UV damage by treating it with a leave-in product that contains UV filters such as ethylhexyl methoxycinnamate (EHMC), methoxydibenz-oylmethane (BM-DBM) or Parsol SLX.

"I love to spend time in the sun, but I see first hand the damaging effects of the sun on hair," says stylist Frederic Fekkai. "That's why I expanded my Summer Hair collection to help keep hair looking healthy and luxurious all summer long.

Fekkai recently expanded his summer hair line to include five sun-safe formulas designed to protect, hydrate and replenish the hair. They contain ingredients such as Solarshield technology, humectants, sunflower seed extract and moringa seed extract to condition and protect the hair from UV damage, pollutants and environmental stressors.

Davines recently launched its Su Suncare System for Hair, a shampoo, conditioner, moisturizing mask, moisturizing cream, moisturizing gel, moisturizing oil and hair and body shampoo that protects hair from sun, sea water and chlorine. Ouidad has its Sun Shield Sun, Swim & Sport Leave-in Spray. Philip Kingsley has developed Swim Cap, a leave-in conditioner with UV protection to protect against the sun as well as ingredients to repair damage caused by chlorine, saltwater and wind. Rene Furterer offers Nutritive Sun Oil, Moisturizing Sun Fluid and After-Sun Nourishing Shampoo. The Phytoplage line by Phyto includes protective treatments with UV filters and moisturizing and repair treatments for after sun. And Kerastase offers its Soleil UV Defense Active line of seven products designed to protect, repair and enhance sun exposed hair.

Redken's UV Rescue line -- After Sun Shampoo and Conditioner, Shimmering Defense Daily Care Protective Lotion, Protective Oil and Sun Milk -- is designed for sun-exposed hair and scalp. The products contain an exclusive Interbond Conditioning System and C2Solar Complex to help combat UV damage, dryness and discoloration, with special ingredients to reconstruct the hair's internal structure and soothe and replenish the hair and scalp.

"The line offers more than just UV protection," Sprankle says. "It's used to help fight against environmental issues that could damage the hair."

The Biolage Sunsorials line contains five products: After-Sun Shampoo, Sun Repair Treatment, Protective Hair Oil, Daily UV Hair Mist It and Protective Sun Gel. In addition to UV filters, the products contain ceramides and anti-oxidants to protect against the harmful elements of summer, Volpi says. It originally was developed for beachgoers on Italy's sun-drenched coasts.

They were designed with summer in mind. The line has a fruity pina colada "beachy" scent, Volpi says. And they're all small enough to toss in a beach bag, Volpi says.

"When you use them in combination, it compounds the amount of protection for the hair," Volpi says. "Hair without any product is much more susceptible to damage."

Fairy Tales recently introduced Lemon-Aid Conditioner to remove chlorine green from kids' hair (Also check out their Coco Cabana Leave-in Sun Spray). And many sun lines include shampoos that remove chlorine and salt from the hair without stripping color.

But don't shampoo too often, says Veronique Morrison, director of education for Mizani. And when you do shampoo, make sure the shampoo isn't too alkaline. Mizani's PuripHying Shampoo and BotaniFying Conditioning Shampoo, which remove chlorine, salt and sweat without stripping the hair of its natural moisture.

Moisture is key during the summer, says Morrison. She recommends putting on a product like Mizani Moisturefuse Moisturizing Conditioner and leaving it on while you're out in the sun. It moisturizes while protecting the hair from the elements. Deep conditioning is a must during the summer, especially if you are outdoors a lot.

"The harshest part of summer is the lack of moisture," Morrison says.