All About Hair

As a child, the only trouble your glossy mane gave you was when it hung in your eyes. Otherwise, you rarely gave it a second thought. Flash forward a few decades, and you've gone from sizzling to fried, with bed-head that won't quit.

So what happened?

As we age, our hair shafts become thinner with less oil. To find out more about hair care, we asked the pros:

Am I going bald if my comb is clogged with hair?

Fret not. We lose 100 hairs a day.

How much conditioner should I use?

Most of us overdo it. Stick to a nickel-size dab of conditioner for hair that ends above the shoulder and a quarter's worth for longer tresses. Apply conditioner from the ears down to prevent limp locks, says Wayne Herndon, a New York hair stylist for film and television stars.

Why does my hair color go brassy and bland?

Blame the sun, which oxidizes color. You can counter a faded hue with a conditioner that promises to hold or refresh color. Or wear hats and use conditioners that offer ultraviolet protection.

Why isn't my dandruff shampoo working?

Dandruff occurs when a scalp fungus (malassezia, formerly called pityrosporum) causes excess shedding of large, oily flakes, Dr. Polis says. Anti-fungal shampoos usually work well for dandruff from this cause. There are other conditions that can mimic dandruff, though. A different problem, psoriasis, causes smaller, dry flecks. A dry scalp, just like dry skin, needs to be moisturized, experts say. Try massaging a few drops of conditioning oil into the scalp.

How can I straighten curly hair?

Japanese straighteners work well, but you can't go back to curls for months. Your hair will stay straight until new, curly hair grows in. Try instead a quarter-size dab of straightening gel in your hair before blow-drying and finishing with a flat iron, says Mr. Herndon. That's how he tames Sarah Jessica Parker's tresses.

Why is my bodybuilding mousse turning down my hair's volume?

"All volumizers coat the hair shaft to make its circumference bigger," Mr. Herndon says. "The problem is they also make hair heavier." Heavier hair lies flatter on your head. To avoid this problem, don't use mousse every day for a long period.

Any other ingredients I should avoid?

Products with too much alcohol dry out hair. So make sure alcohol is low on a bottle's ingredients list. And keep blow-dryers 6 to 12 inches from your hair, using a cooler setting.