9.1 Haircutting Procedures for Different Hair Types

Haircutting is only 3% of the PSI National Cosmetology Theory exam, but the underlying principles-texture analysis, elevation, and line design-connect directly to the much larger domains of hair analysis and client consultation. On the theory exam, expect questions that ask you to match a cutting approach to a described hair type rather than to perform a physical technique. Understanding why a cutter changes elevation or cutting method for different textures is more testable than memorizing a single "correct" haircut.

Why Hair Type Changes the Cutting Approach

Every head of hair has a natural growth pattern and curl pattern that determines how it falls once released from tension. A cutter who ignores natural texture and cuts every head the same way will produce a line that looks correct while wet or under tension, but distorts once the hair dries and springs back into its natural shape. This is the single most tested concept in haircutting theory: wet or stretched length is not the same as finished, dry length, and the gap between the two grows as curl pattern gets tighter.

Straight Hair

Straight hair has little to no shrinkage between wet and dry states, so a line cut wet will fall almost exactly where it was cut once dry. This makes straight hair the most forgiving texture to read, but also the least forgiving of cutting error, because every line, notch, or uneven section is fully visible with no curl to camouflage it.

• Elevation control is critical. Because there is no shrinkage to compensate for a mistake, elevation angle (0°, 45°, 90°, etc.) must be held consistently across each section to avoid visible steps in the perimeter.
• Cross-checking is essential. After cutting on one parting pattern (e.g., horizontal), the cutter re-checks by parting in the opposite direction (e.g., vertical) to catch any unevenness the first pattern missed.
• Reflects light and movement. Because strands lie flat against each other, straight hair shows shine and single-length blunt lines especially clearly, so blunt cuts and heavy, one-length perimeters are popular finished looks.

Wavy Hair

Wavy hair sits between straight and curly on the texture spectrum and is often the least predictable of the four categories because the wave pattern can vary in size and consistency across a single head-tighter near the nape, looser at the crown, for example.

• Cut wet, verify dry. Wavy hair is commonly cut wet to establish an accurate baseline, but because waves compress somewhat as they dry and fall into their pattern, the cutter should check the shape again after the hair air-dries or is dried with minimal tension.
• Watch for inconsistent shrinkage. Since wave pattern often changes across the head, a line that looks even immediately after a wet cut can appear uneven once each section springs back by a different amount.
• Layering supports movement. Because wavy hair has natural volume and movement, layers are frequently used to work with the pattern instead of against it, allowing the wave to show through rather than being weighed down by heavy, blunt lengths.

Curly Hair

Curly hair has a well-defined, consistent curl pattern (commonly described using loose to tight ringlet or spiral categories) and shrinks noticeably-often 20% to more than 50% of stretched length-once it dries and the curl fully forms.

• Dry cutting is common. Many licensed cutters cut curly hair dry, or cut wet and allow it to fully dry before final detailing, specifically because shrinkage makes wet length an unreliable guide to the finished result.
• Reduced elevation and tension. Pulling curly hair to full tension while cutting can result in lengths that look correct while stretched but become dramatically shorter than intended once the curl relaxes back to its natural state.
• Cut curl by curl, not just section by section. Because individual curls in the same section can have different diameters, some cutters shape hair by evaluating individual curls or small curl clusters to keep the overall silhouette balanced.

Overly Curly (Tightly Coiled) Hair

Overly curly, tightly coiled hair (sometimes categorized as the tightest curl patterns) has the most shrinkage of any texture and requires the most conservative approach to avoid cutting the hair shorter than the client intended.

• Greatest shrinkage risk. Shrinkage in tightly coiled hair can exceed 50% to 75% of stretched length, meaning even a small amount of tension during cutting can translate into a dramatically shorter dry result.
• Fragility and structure. Tightly coiled strands have more twists and turns along the hair shaft, which means the cuticle is more exposed at each bend, making the hair more prone to breakage from excessive tension, aggressive combing, or repeated over-cutting of the same area.
• Blunt, low-manipulation cutting reduces damage. Because each strand's cuticle is already under mechanical stress from its own coil pattern, minimizing additional tension and handling during the cut helps preserve hair strength and definition.
• Client communication is essential. Because shrinkage is so significant, cutters must clearly communicate expected dry length before cutting so the client understands how the visible wet or stretched length relates to the finished, dry look.

Elevation, Angle, and Line Design

Regardless of texture, three cutting variables determine the shape produced:

• 0° elevation produces a blunt, one-length result with maximum weight retained at the perimeter-often used for straight hair styles designed to show a heavy, solid edge.
• 45° elevation produces graduated shapes with moderate weight removal, a common transition angle for wavy or layered looks.
• 90° elevation or higher removes the most weight and is typically used to build layers or add movement, which is often desirable on curlier textures to reduce bulk and support curl definition rather than weight that pulls the curl pattern down.

Consultation Before Cutting

A thorough consultation precedes every cut and should confirm: natural texture and curl pattern, current condition and porosity, growth pattern (including cowlicks or whorls), desired maintenance level, and how the client typically wears and dries their hair day to day. A style that looks correct in the chair but requires styling tools the client does not use at home will not satisfy the client once they leave the salon-so matching the cut to the client's real-world routine is as much a professional and legal-consultation responsibility as it is a technical one.

Wet vs. Dry Cutting Decisions

On the theory exam, questions in this section typically describe a client's hair type and either ask which cutting consideration applies (e.g., "why would a cutter avoid cutting a tightly coiled client's hair to full tension") or ask the candidate to identify which technique-wet or dry cutting, high or low elevation-matches a described outcome. Focus on the underlying reasoning (shrinkage, tension, and visibility of error) rather than memorizing exact percentages, since the core relationship between texture and technique is what is being tested.