Why is a strand test necessary?

A strand test determines how the hair will react to a chemical service before applying to the full head. It reveals processing time needed, potential damage, colour result, and curl formation. It is a legal and insurance requirement in many cases and protects both stylist and client from unexpected outcomes or damage.

How do I perform a strand test?

Take a small section of hair (usually from behind the ear or nape), apply the product as you would for the full service, and process for the recommended time. Check at regular intervals. After rinsing and drying, assess the colour result, hair elasticity, and overall condition. Record all findings on the client card.

How long before the appointment should I do a strand test?

A strand test should be done 24-48 hours before the full service. Colour and toner tests need at least 24 hours to check for delayed reactions. Perm and relaxer tests should be done 48 hours before to fully assess curl development, elasticity and potential damage that may not be immediately visible.

What should I look for in strand test results?

Check for: colour accuracy (right shade and tone), hair elasticity (does it stretch and return or snap?), cuticle condition (rough or smooth?), overall texture change, and any adverse reaction (breakage, melting, excessive porosity). If the result is poor, adjust the formula, timing, or recommend against the service.

CutCalcs

Strand Test Calculator — Timing & Safety Planning

Plan strand test timing and record results for chemical service safety.

Service Type

Hair Condition

Previous Treatment

Target Result

How We Calculate This

This calculator estimates strand test processing time and check intervals based on the planned chemical service, hair condition and previous treatment history.

The formula

Test duration = Base time ± Condition adjustment ± Previous treatment adjustment ± Target adjustment

Poor condition hair reduces safe testing time by 10 minutes
Previously bleached hair reduces safe testing time by 8 minutes
Bleach strand tests should be checked every 5 minutes
Allow 24-48 hours between strand test and full service

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always perform a strand test before chemical services.