Thinning
Description
Thinning reduces bulk using thinning shears or texturizing scissors. Learn tooth counts, thinning rates, placement, and how to avoid common thinning mistakes.
Thinning (セニング)
Quick look
- What it is: Reducing bulk and density using toothed scissors (thinning shears or blending shears)
- Also called: Sening (セニング) in Japanese salon terminology
- Key requirement: Choosing the right tooth count for the desired cut rate
- Tool: Thinning shears with specific tooth profiles
Why it matters
Thinning is the primary method for removing bulk without changing shape. A well-executed thinning pass takes out interior weight while preserving the outline. Done poorly, it creates holes, shelf lines, and that dreaded “moth-eaten” look. The difference comes down to tooth count, tooth design, and placement.
The tooth count directly controls how much hair gets cut per close. Here’s the general breakdown:
| Tooth count | Cut rate | Best for |
|---|---|---|
| 38 to 46 teeth | 5 to 15% | Subtle blending, fine hair, finishing |
| 30 to 35 teeth | 15 to 25% | General bulk removal, medium density |
| 10 to 15 teeth | 40 to 70% | Aggressive weight removal, very thick hair, chunking |
These ranges vary by manufacturer. A 30-tooth shear from one maker may cut differently than a 30-tooth from another because of differences in tooth spacing, tooth width, and whether the teeth are flat or curved.
Recommended scissors
| Feature | Recommendation |
|---|---|
| Type | Thinning shears (one toothed blade, one straight blade) or blending shears (both blades toothed) |
| Tooth count | Match to your most common need (see table above) |
| Tooth profile | See tooth tip profiles for V-shaped vs. U-shaped vs. flat options |
| Size | 5.5 to 6.5 inch |
Technique notes
Placement is where most mistakes happen. Never thin the hairline, the part line, or the top surface layer. These areas reveal thinning marks immediately. Work in the interior of sections, roughly 2 to 4 inches from the root for mid-length hair.
Close the shears once per section, then release. Don’t “chatter” (rapidly opening and closing) in the same spot. Each closure removes a percentage of hair from that exact location. Multiple closures stack and create gaps.
For fine or damaged hair, use high tooth counts (38+) that remove minimal hair per pass. You can always make another pass. For coarse, dense hair, lower tooth counts work faster and produce more visible texture.
Japanese thinning technique often involves “sening” (セニング) in specific geometric patterns across the head. The pattern controls where weight lives in the finished shape. This systematic approach produces more predictable results than random thinning.
Related links
| Tooth Tip Profiles | Texturizing | Scissor Sizes | Point Cut |
Related guide: Tool Mastery: Thinning Cut Rates
Sources
- KAMIU (kamiu.jp) thinning shear selection and technique guides
- Joewell Scissors tooth design technical documentation
- Hikari Scissors professional education materials on sening technique
Frequently Asked Questions
Higher tooth counts remove less hair per close, lower tooth counts remove more. 38 to 46 teeth produces 5 to 15% removal for subtle blending on fine hair and finishing work; 30 to 35 teeth produces 15 to 25% for general bulk removal; 10 to 15 teeth produces 40 to 70% for aggressive weight removal on very thick hair or for deliberate chunking. These ranges vary by manufacturer because tooth spacing and width differ, so two 30-tooth shears from different brands can cut differently.
Never thin the hairline, the part line, or the top surface layer — those areas reveal thinning marks immediately and cannot be fixed without growing out the cut. Work in the interior of sections, roughly 2 to 4 inches from the root for mid-length hair. Close the shears once per section, then release — do not chatter (rapidly opening and closing) in the same spot, because each closure stacks a percentage of hair removal and multiple closures in one place create visible gaps.
Japanese thinning technique (セニング, sening) involves working in specific geometric patterns across the head rather than placing thinning randomly. The pattern controls where weight lives in the finished shape, producing more predictable results than freehand thinning. Pair the pattern with the right tooth count: high counts (38+) on fine or damaged hair to remove minimal hair per pass, lower counts for coarse dense hair where you need to work faster and can tolerate more visible texture.