Smoothing (Straightening)
What It Does:
Coats each strand with detanglers and moisturizers, making hair more resistant to humidity and easier to straighten with products and a blow-dryer. Deposits reflective particles to increase shine. "We also load these formulas with fatty alcohols," says Dianna Kenneally, senior scientist at Physique, "so they detangle as you rinse."
What It Doesn't Do:
Actually straighten hair. "Only heat-styling does that," Kenneally says.
What to Look For:
Shine-enhancing dimethicone for luminous results, and humidity-resistant smoothers like cetyl and stearyl alcohols for frizz prevention.
Volumizing (also called thickening or body-building)
What It Does:
Temporarily thickens fine strands with positively charged proteins and polymers that attach to the hair. "It used to be enough to puff up the hair by coating it," says Joanne Crudelle, senior development manager for Unilever. "Now we want to make it fuller without making it feel coated or tacky." The newest formulas also use lightweight moisturizers like panthenol and vitamin E to condition hair without weighing it down.
What It Doesn't Do:
Defy gravity.
What to Look For:
Formulas containing sugars, wheat starch and amino acids to add fullness without stiffness. And polyquaternarium-10 to add texture, make styling easier, and give hair a less slippery feel. If styling residue is making your hair limp, try an alpha hydroxy acid like citric acid, which removes buildup.
Curl-Enhancing
What It Does:
Enhances already existing waves or ringlets by tightening and separating individual strands. Uses moisturizers called humectants to attract water from the air and keep curls springy. "It's like using a mister on your curls," says Lana Hill, technical director for KMS.
What It Doesn't Do:
Create waves in straight hair or ringlets in wavy hair.
What to Look For:
Magnesium and quinoa, which help to tighten the hydrogen bonds in the hair. Also important are the humectants—including glycerin and honey—which draw curl-boosting water from the air.
Repairing (also called moisturizing, restructuring, intensive conditioning)
What It Does:
Uses relatively new magnetic technology to bond positively charged proteins to negatively charged, damaged, porous areas on the hair strand—creating a smoother, silkier surface that makes hair easier to style and brush. The fortified strands are less prone to breakage. "The damaged areas do absorb conditioners," Cannell says. "But after a week or two of regular use, you reach the maximum level of repair."
What It Doesn't Do:
Repair split ends or speed up the growth of broken strands.
What to Look For:
Formulas rich in proteins (such as silk or wheat) and vitamins (especially B and E), which repair rough spots in the strands' surface. Also important are moisturizers that contain fatty alcohols (cetyl, stearyl or ceramides) and oleic acid.
Color-Reviving
What It Does:
Uses conditioners and sunscreens to protect strands and prevent pigment from leaking out of color-treated hair. Adds shine-enhancing particles that boost the apparent intensity of your hue.
What It Doesn't Do:
Add new pigment to your hair or weeks to your dye job.
What to Look For:
UV filters like oxybenzone and conditioners like panthenol and vitamin E that seal the cuticle to keep color from seeping out.
Color-Enhancing
What It Does:
Deposits pigment onto hair to change or enhance existing color (natural or chemically created).
What It Doesn't Do:
Bleach, lighten, or dramatically change color. "It's more of a glazed effect," says Luisa Cerda, a research scientist at Clairol. "Brunettes who use a red shampoo would appear auburn. Blondes would look strawberry blonde."
What to Look For:
Color pigments as one of the first five ingredients.
Scalp Rejuvinating
What It Does:
Prepares your scalp for hair-growth solutions like Rogaine.
What It Doesn't Do:
Grow hair. "Even shampoos that are companions to minoxidol-containing solutions, like Nioxin or Progaine, can't grow hair by themselves," says Amy McMichael, M.D., associate professor of dermatology and director of the hair disorders clinic at Wake Forest University School of Medicine. "But other shampoos may reduce their effectiveness."
What to Look For:
Those containing amino and/or fatty acids help maintain a good pH level so topical solutions can penetrate more deeply into the follicle.
