5.2 Blowdrying, Thermal Curling, and Thermal Tool Safety

Why this topic matters

The Hairstyling domain also includes blowdrying procedures, thermal curling procedures, and precautions for use of thermal styling tools (e.g., testing temperature, protecting scalp). These are the heat services most likely to burn a client, so PSI's questions focus on safety as much as technique. Tennessee's master barber curriculum includes haircutting, hairstyling, and hairsetting, and the student kit required after 100 hours includes a blow dryer, a curling iron, vent-type brushes, and styling brushes (Rule 0200-01-.15).

The science: hydrogen bonds

Water and heat break the weak hydrogen bonds between keratin chains. As hair dries or cools in a new shape, those bonds re-form and hold it. That is why a blowout or iron curl is temporary. It lasts until water, sweat, or humidity breaks the hydrogen bonds again. Disulfide bonds, the ones perms and relaxers change, are not affected by normal thermal styling.

Blowdrying

Parts and attachments

Brushes

• Vent brush: fast drying and loose direction.
• Round brush: volume, bend, and smoothness. A smaller barrel gives more curl.
• Paddle or cushion brush: smoothing larger sections.
• Styling or grooming brush: finishing short men's styles.

Technique

1. Towel-blot and comb out the hair, and apply a heat protectant or styling product.
2. Rough-dry to remove excess moisture, directing air down the hair shaft from scalp to ends so the cuticle lies flat.
3. Section the hair and dry each section with a brush. To create volume, lift the base and direct air at the root. To keep the hair flat, dry it in the direction it will be worn.
4. Keep the dryer moving. Holding it in one spot overheats the hair and the scalp.
5. Aim the nozzle away from the scalp and ears. Keep it a few inches from the hair and tilted along the brush.
6. Finish with the cool shot to set the shape, then apply finishing product.

For curly or tightly coiled hair: a diffuser dries curls without breaking up the pattern. Stretching coily hair with a brush and dryer before thermal styling needs gentle tension and moderate heat.

Thermal curling

Thermal irons include the traditional Marcel iron (a stove-heated or electric iron with a rod and a shell) and modern electric curling irons.

Parts

• Rod (prong): the solid round barrel the hair wraps around
• Shell (groove or clamp): the curved half that closes over the hair
• Handles: open and close the shell. In a "click" technique, the barber rolls the iron and opens and closes the shell to move hair smoothly without crimping it.

Base placement and volume

Procedure

1. Start with clean, completely dry hair.
2. Take sections no wider or deeper than the iron can handle.
3. Place a comb between the iron and the scalp to protect the skin.
4. Insert the ends evenly and roll the iron to wind the hair. Keep the ends inside the shell so they do not "fishhook."
5. Hold only long enough to set the curl, then release and let it cool before combing out.

Flat irons and pressing

Flat irons smooth hair between two heated plates. Use small sections, move the iron steadily from base to ends, and do not iron wet hair. Trapped water flashes to steam and damages the cuticle. Pressing combs (thermal straightening) follow the same safety rules, plus extra care near the hairline.

Precautions for thermal tools

PSI names two precautions, testing temperature and protecting the scalp. Here is the full safety list.

Testing temperature

• Test a heated iron on a white tissue or cloth or on a test strand before using it on the client. Scorching, yellowing, or smoke means it is too hot.
• Use lower heat on fine, lightened, gray, color-treated, or damaged hair. Coarse, resistant hair can take more heat, but still use only what the hair needs.
• Adjustable professional irons let you set the temperature. Start low and raise it only as needed.

Protecting the scalp and skin

• Keep a heat-resistant comb between the iron and the scalp. Do not use a celluloid or flammable comb.
• Shield the ears, forehead, and neck. Warn the client before bringing a hot tool near the face.
• Never rest a hot tool on the client, the cape, or the station surface. Use a heat-resistant stand.

Protecting the hair

• Use a heat protectant.
• Do not thermal-style hair that is chemically weakened, such as over-lightened or just relaxed, unless the manufacturer allows it. The hair can break or melt.
• Keep synthetic hairpieces and extensions away from heat unless they are rated for it.

Tool care and electrical safety

• Clean product buildup off irons when they are cool and unplugged.
• Inspect cords and plugs, keep tools away from water, and unplug them after use (section 3.7).
• Disinfect combs and brushes between clients by cleaning and full immersion. Remove hair from brushes first.

If a burn happens

1. Stop the service and remove the heat source.
2. Cool the burn under cool, not ice-cold, running water for several minutes.
3. Do not apply butter, ointment, or ice. Cover it lightly with a clean, dry dressing.
4. Refer the client to a physician if the burn blisters, is large, or is on the face, and record the incident.

Exam checklist

• Air goes scalp to ends.
• Diffuser for curls, nozzle for focused smoothing.
• Comb between iron and scalp.
• Tissue test for iron temperature.
• Lower heat for fine, lightened, or damaged hair.
• Styles made with heat change hydrogen bonds only.