Type 1 hair has no curl pattern. The letter says how fine or coarse the strands are and how much body they hold, and that changes the routine more than you would expect.
Short version: 1A is fine and flat, 1B has some body and a bend at the ends, 1C is coarse with frizz at the crown. All three get oily fast, so shampoo goes on the scalp, conditioner goes on the ends, and heat stays on low or medium with a protectant.
Straight hair gets oily faster than any other type, because scalp oil travels down a straight strand with nothing to stop it. Most of the care is about managing that oil without drying out the ends.
1A hair
Very fine, soft and completely flat. It won't hold a curl from an iron for long and looks greasy within a day of washing. Heavy creams, oils and silicone serums pull it flatter still.
What helps: a lightweight volumizing shampoo, conditioner on the ends only, and a root-lift spray or a little mousse at the roots before blow-drying.
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- Keranique Volumizing MousseLightweight mousse for fine, straight or wavy hair that goes flat.Check price
- Pantene Pro-V Sheer Volume ConditionerPantene's volume line. Keep it on the mid-lengths and ends.Check price
1B hair
Still straight, with more body and a slight bend at the ends. It holds a style better than 1A and can take a light leave-in on the lengths without collapsing.
What helps: the same light cleansing, a lightweight leave-in on mid-lengths to ends, and a round brush or large velcro rollers when you want movement.
1C hair
Coarse, thick strands with a visible bend and some frizz, especially at the crown. It resists curling and can look puffy in humidity. It is the type 1 hair most likely to feel dry at the ends while the scalp is oily.
What helps: a smoothing conditioner, a drop of serum or light oil on the ends only, and heat protectant before any blow-dry or iron.
- John Frieda Frizz Ease Extra Strength SerumA few drops on the ends. The brand says it shields from heat and humidity.Check price
Washing
The American Academy of Dermatology says people with straight hair and an oily scalp may want to shampoo every day, and that shampoo belongs on the scalp, not the whole length. The suds that rinse through are enough for the ends. Dry shampoo between washes absorbs oil at the roots but it builds up, so a clarifying wash every week or two keeps the scalp clean.
- Vanicream ShampooMade for sensitive skin. Sold to remove buildup from conditioners and sprays, and to cut flaking and excess oil.Check price
- CeraVe Gentle Hydrating ShampooFor sensitive scalps. No sulfates or fragrance; ceramides, niacinamide and hyaluronic acid.Check price
Conditioner and drying
For fine or straight hair, the AAD's advice is to put conditioner on the ends. Wrap hair in a towel or an old t-shirt to absorb water instead of rubbing, and let it dry a little before you comb it. Wet straight hair stretches and snaps more easily.
- Bondi SPA Microfiber Hair TowelMicrofiber in place of rough cotton. Sold for plopping, less frizz and faster drying.Check price
Heat
Type 1 hair is the most often heat-styled, which is why it so often has dry, split ends while the roots look fine. Use low or medium heat settings and a heat protectant every time. If your ends are already rough, read the high porosity guide: heat damage raises porosity, and the fix is the same.
- CHI 44 Iron Guard Thermal Protection SprayWeightless spray, rated by CHI up to 450°F.Check price
- TRESemmé Keratin Smooth Heat Protection SprayDrugstore heat spray with keratin and marula oil, made for flat irons.Check price
FAQ
What is the difference between 1A, 1B and 1C hair?
Strand thickness and body. 1A is very fine and lies completely flat, 1B has more body and a slight bend at the ends, and 1C is coarse and thick with a visible bend and some frizz at the crown.
How often should you wash straight hair?
As often as the scalp gets oily, which for many people with type 1 hair is every day. The AAD says people with straight hair and an oily scalp may want to shampoo daily, with the shampoo on the scalp rather than the lengths.
Why does straight hair get greasy so fast?
Scalp oil travels down a straight strand with nothing to slow it, so the whole length looks oily sooner than wavy or curly hair would. Heavy creams and oils on the roots make it worse.
How do you get volume in 1A hair?
Keep weight off the roots. Use a lightweight volumizing shampoo, conditioner on the ends only, and a root-lift spray or a little mousse at the roots before blow-drying.
Should straight hair use a heat protectant?
Yes, every time you use a dryer or an iron. The AAD lists excessive heat as a cause of hair damage and advises low or medium settings with a heat protectant.
The letter is only part of it. Two people with 1B hair can have very different porosity and scalp oil. The quiz asks about both and builds a routine from the answers.
Sources: American Academy of Dermatology, Tips for healthy hair. Pattern descriptions follow the Andre Walker system as extended online; see the hair type chart.