Straight hair (type 1 in the common 1–4 shorthand) has little or no curve along its length. Under the microscope straighter hairs tend to have a rounder cross-section than curly ones.
The American Academy of Dermatology notes that people with straight hair and an oily scalp may want to shampoo every day, and suggests conditioning just the ends of fine or straight hair and letting straight hair dry a little before combing it. A hair-science review adds that leave-in products can make straight hair look oily or dull.
Care priorities
Wash as often as your scalp needs — often more frequently than curly hair.
Keep conditioner and heavier products away from the roots.
Leave-in products can make straight hair look oily or dull, so use them sparingly.
Fine straight hair is easily weighed down: lighter formulas, smaller amounts.
The patterns
1A: Completely straight from root to tip, with no bend.
1B: Straight, with some body or a slight bend at the ends.
1C: Mostly straight, with a hint of wave and more body.
Care basics
Washing
If your scalp gets oily quickly, it's fine to shampoo every day — the American Academy of Dermatology says people with straight hair and an oily scalp may want to.
Conditioning
Concentrate conditioner on the ends to avoid flat, greasy roots, and let hair dry a little before combing.
Styling
Use the lowest heat that works with a heat protectant; keep the dryer moving about 15cm away and straighten only dry hair.
Night-time
Sleep with hair loose or in a loose plait; avoid tight elastics.
Key ingredients: Genamine-si technology; moisturising agents (ingredient list includes niacinamide, castor seed oil and hydrolysed wheat, corn and soy proteins)
Key features: High-velocity airflow (Shark: 0-100 mph in under a second); Scalp Shield Mode that lowers the air temperature for scalp comfort and root drying; Shark says temperature is measured and regulated 1,000 times a second and never exceeds 110°C; settings adjust automatically to each attachment; 240 V. In the box: main unit, Turbo Concentrator, QuickSmooth Brush, FrizzFighter Finishing Tool, Express TouchUp Brush, diffuser (DefrizzFast Diffuser) and storage bag. 2-year guarantee on registration (UK & ROI).
Key features: Brushless motor delivering 75 mph airflow (as stated on the retailer page); 'Aeroprecis' technology (described as a combination of four advanced internal elements); patented etched air-intake grille; internal impeller to reduce air turbulence; contoured precision nozzle; variable power and temperature controls with cool shot; acoustic system for lower noise; 9 ft power cable; UK 3-pin plug; 2-year manufacturer warranty.
Key features: 2000W motor; air speeds up to 120 km/h (Remington figure); 8 heat/speed combinations (per the product page; the booklet describes a heat switch with low/medium/high, a fast/slow speed button and a cool shot button); Thermacare sensor that Remington says regulates air temperature to protect against extreme heat. Attachments: Slim Styling Concentrator, Flyaway Tamer, Gentle Drying Diffuser and Curl Defining Diffuser (magnetic prongs that fit the diffuser bowl). Also has a hang-up loop and comes with a storage bag.
Key features: Flexible teeth that the retailer copy says 'flex and flick' through hair; ergonomically shaped, handle-free body. Described as suitable for all hair types, including fragile, colour-treated or fine hair, hair extensions and weaves.
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