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Turn over almost any bottle marketed to curly hair and you will find the same two promises: sulfate-free, silicone-free. The idea was popularized by the Curly Girl Method, set out by the stylist Lorraine Massey in the early 2000s, and it has helped a great many people. It has also hardened into a rule that is repeated more often than it is explained.
Neither ingredient is dangerous. Both involve a trade, and it is worth understanding the trade before deciding which side of it you want to be on.
Sulfates
Sulfates are detergents. The two you will see most are sodium lauryl sulfate and sodium laureth sulfate, usually near the top of a shampoo's ingredient list. They are inexpensive, they lather richly and they are extremely good at removing oil.
That last quality is the problem. Curly hair is already short of oil along its length, because sebum from the scalp does not travel easily down a spiral. A strong detergent removes what little is there, and the hair responds with dryness and frizz.
The gentler alternatives
Sulfate-free shampoos clean with milder surfactants. Names to look for include:
- Cocamidopropyl betaine
- Sodium cocoyl isethionate
- Decyl glucoside and coco-glucoside
- Sodium lauroyl methyl isethionate
One caution. "Sulfate-free" is a marketing term, not a guarantee of gentleness. Sodium C14-16 olefin sulfonate, for example, is technically not a sulfate and cleans almost as aggressively as one. That can be useful in a clarifying shampoo and unwelcome in an everyday one.
Do you ever need a sulfate?
Occasionally, perhaps. If you use heavy butters, non-soluble silicones or live with hard water, a stronger wash every few weeks removes what a gentle one leaves behind. Many people manage with a sulfate-free clarifying shampoo instead.
Silicones
Silicones are conditioning agents. They form a thin, smooth film over the hair that adds shine, reduces friction, eases detangling and protects against heat. On a label they usually end in -cone, -conol or -siloxane.
The objection is buildup. Some silicones do not dissolve in water. If you wash only with a gentle shampoo, they can accumulate over weeks, until the hair feels coated, limp and resistant to moisture. Removing them takes a stronger cleanser, which is the cycle the sulfate-free, silicone-free approach is designed to break.
Silicones are not bad for hair. They are incompatible with a routine that never clarifies.
Not all silicones behave alike
| Type | Examples | Behavior |
|---|---|---|
| Non-soluble | Dimethicone, dimethiconol | Long-lasting; builds up without clarifying |
| Self-limiting | Amodimethicone | Clings to damaged areas; resists layering on itself |
| Evaporating | Cyclomethicone, cyclopentasiloxane | Largely evaporates after application |
| Water-soluble | PEG- and PPG- dimethicones, dimethicone copolyol | Rinses out with water or gentle shampoo |
A product containing a water-soluble silicone is, for practical purposes, compatible with a gentle routine.
So what should you do?
There are two coherent approaches. Choose one and be consistent.
Avoid both. Use sulfate-free shampoo and silicone-free conditioners and stylers. Nothing builds up that a gentle wash cannot remove. This suits dry, coily and tightly curled hair particularly well, and it is the simpler system to follow.
Use silicones deliberately. Keep them for where they help most, such as heat protection or a smoothing serum, and clarify every few weeks. This often suits wavy and fine hair, which silicones can smooth without the weight of oils and butters.
What does not work is the combination in between: heavy silicones every day, washed only with a co-wash. That is the routine that produces the dull, coated hair the whole debate started with.
Reading a label quickly
Ingredients are listed in descending order of quantity. The first five or six make up most of the product. A silicone at the bottom of a long list is present in a trace. A sulfate in second place, straight after water, is the main cleanser. Read the top of the list and you will know most of what the bottle is going to do.
For recommendations by curl pattern, see The Best Shampoos for Curly Hair.