Why does colour history matter?

Each colour application adds another layer of pigment to the hair shaft and alters the cuticle. Over time, this creates buildup that makes hair appear darker or muddier at the mid-lengths and ends compared to fresh roots. Understanding colour history helps stylists choose the right approach for consistent, beautiful results.

What is colour buildup?

Colour buildup occurs when permanent colour is repeatedly applied to already-coloured hair. Each application deposits more artificial pigment. Over 6-12+ applications, mid-lengths and ends become noticeably darker and denser than fresh root colour. This creates visible "bands" where old and new colour meet.

How does colour history affect porosity?

Each chemical colour service opens and closes the cuticle, causing cumulative damage. After many services, the cuticle becomes permanently raised in places, increasing porosity. High-porosity hair absorbs colour unevenly and rapidly, often going darker than intended. It also loses colour faster between visits.

How do I deal with heavy colour buildup?

Options include: applying roots-only colour and pulling through ends for the last 5 minutes only; using a colour remover to strip buildup before recolouring; switching to demi-permanent on lengths to reduce further damage; using a porosity equaliser before colour; or doing a full colour correction to even everything out.

CutCalcs

Colour History Calculator — Buildup & Porosity Assessment

Track colour formulation history and calculate colour buildup over visits.

Colour Visits

Total colour services on this hair

Weeks Between Visits

Colour Type

Current Level

1 = black, 10 = lightest blonde

How We Calculate This

This calculator assesses colour buildup and porosity based on the number of colour services, the time period and the type of colour used.

The scoring system

Buildup score = Number of colour visits x Colour type factor

Permanent colour: 1.5x buildup factor per visit
Bleach: 2x buildup factor per visit
Demi-permanent: 0.8x factor
Semi-permanent: 0.5x factor (least buildup)

Frequently Asked Questions

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Last updated: February 2026

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