All deep conditioners are not created equal, stresses Jonathan Torch of the Curly Hair Institute in Canada. There are truly therapeutic deep conditioners, and then there are cosmetic conditioners that leave a silky feel but do nothing to repair or hydrate the hair shaft.
"Simply coating the cuticle will not cure the dehydration properly," Torch says.
Shai of Capella Salon in Studio City, Calif. recommends testing the elasticity of the hair to see if it needs strength or moisture. If the hair snaps easily with the stretch test, he suggests a conditioner that rebuilds the hair with protein, such as Kerastase Vita Ciment Pro Treatment. If the hair has some elasticity, he recommends a more moisturizing deep conditioner.
Many deep conditioners contain large amounts of protein, which can be drying for some curlies, says Jessica McGuinty, creator of the Jessicurl line of products. If that is the case, opt for a deep conditioner with little or no protein, or alternate between a protein deep treatment and a moisturizing deep treatment.
It is best to use a deep conditioner once a week, especially for hair that is chemically treated, colored or relaxed, says Lucie Doughty, editorial director for John Paul Mitchell Systems. For "virgin" hair that is not subjected to heat styling tools regularly, every two weeks may be adequate in the winter.
The most effective application is to apply a generous amount of the deep conditioner to wet or damp hair that has just been cleansed. Concentrate on the ends, which tend to be more fragile and dry, Branch says. In some cases, the conditioner can be left on 5 to 10 minutes while you're in the shower, so the steam helps the conditioner penetrate into the hair.
For more damaged hair, leave it on longer -- 15 minutes or longer.
Most deep treatments are more beneficial when used with heat, McGuinty says. The heat temporarily swells the cuticle and allows the conditioner to better penetrate the hair shaft. For optimal results, pile the hair into a cap and sit under a heated dryer. Or use a micro heat cap.
Skip the heat if your hair has been colored within the last two weeks because it can cause the color to leech out, McGuinty cautions.
If you're strapped for time, Shai recommends putting in the deep conditioner, covering it with a hat and going out for a jog or walk, gardening, cleaning, etc.
"Your body heat will give the conditioner the extra boost it needs to make the hair feel softer and bouncier," he says.
After you rinse the conditioner out, do not use a towel to dry it. The rough texture of the towel will undo some of the benefits of the deep conditioner, roughing up the cuticle and inviting unfriendly frizzies, Shai says.
Christo stresses that deep conditioning treatments must be used on a regular basis.
"Treatments are temporary, just like everything else in life!" he says. "They are an ongoing process."