Plant-Based Colour on Long and Thick Hair: Complete Guide

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Plant-Based Colour on Long and Thick Hair: Complete Guide

Colouring long or thick hair with plant-based powder presents two main challenges that many users underestimate: the quantity of product needed and the uniformity of colour from roots to ends. Both are managed with careful preparation and the right technique.

The Specifics of Long and Thick Hair

Long hair has a longer history than the roots. The ends have undergone more exposure — sun, washing, heat styling — and are often more porous. They can react differently to colour than the roots, which benefit from scalp warmth and a fresher fibre.

Thick hair presents a different challenge: the sheer volume of fibre requires substantially more product and a more systematic application technique to avoid patchy results.

Understanding both factors before you start is the key to a professional-looking result at home.

Calculating Powder Quantity Precisely

Tresse Paris general rule: 1 gram of powder per centimetre of length per centimetre of head circumference, divided by 2. In practice, for standard density:

  • Short bob (15–25 cm): 150–200 g
  • Shoulder length (25–35 cm): 200–280 g
  • Mid-back (35–50 cm): 280–380 g
  • Long (50–65 cm): 380–480 g
  • Very long (>65 cm): 480–600 g

Thick hair: add 25–30% to the above quantities. Curly or coily hair: add a further 15–20% (the apparent volume is deceptive — there is more surface area to cover). The golden rule: always prepare more than you think you need. Excess paste is discarded; a missed area is difficult to correct.

Preparing the Paste for Large Volumes

For large quantities (>200 g), prepare the paste in two batches to maintain a homogeneous temperature throughout the application:

  1. Weigh and divide the powder into two equal portions
  2. Heat water to 70°C (or 68°C for a sensitive scalp)
  3. Prepare the first batch — use the thermometer (critical)
  4. Begin applying the first batch
  5. Prepare the second batch during application (water cools while you work)

Target consistency: thick yoghurt. Too thin = runs onto the forehead and neck. Too thick = does not penetrate the lengths properly and creates uneven coverage.

Application Technique: Section by Section

The section method is essential for even coverage on long hair:

  1. Divide into 4 to 6 sections (two on each side + top) depending on density. The thicker the hair, the smaller the sections.
  2. Start at the roots and grey areas: the least porous zones require the most product and the most processing time — apply there first.
  3. Work down to the lengths: lengths are more porous and absorb colour faster. Treating them after the roots balances colour uptake across the full length.
  4. Saturate each section thoroughly: the plant paste must penetrate the entire section, not just coat the surface. Use the back of the brush to press the paste into each section.
  5. Pin up into a bun under a thermal cap or cling film. Long hair gathered in a spiral retains heat better and ensures more even processing.

Adapted Processing Times

Processing time depends on texture, density and colour goal:

  • Fine to medium hair: 45 minutes to 1 hour
  • Thick hair: 1 hour to 1 hour 30 minutes
  • Very thick or curly hair: 1 hour 30 minutes to 2 hours
  • 2-step method: these times apply to each step separately

On long hair, heat is better retained under the cap — processing time may be slightly reduced compared to short hair exposed to ambient air.

Rinsing: The Critical Step on Long Hair

Rinsing is the most frequently underestimated step, and the one where the most common errors occur on long hair:

  • Minimum 10 to 15 minutes under lukewarm running water — much more than the 3–5 minutes sufficient for short hair.
  • Use a wide-tooth comb under the jet to dislodge paste particles embedded in the lengths and curls.
  • Rinse section by section if the hair is very dense — do not let the lengths tangle under the jet.
  • Water must run completely clear. Slightly coloured water means residues are still present — keep rinsing.
  • Finish with a jet of cool (not cold) water to seal the cuticle and lock in the pigments.

Special Case: Long Curly and Coily Hair

Long curly or coily hair combines the challenges of both hair types. Technical specifics:

  • Prepare the paste slightly more fluid (+8–10% water) so it works into the curls without weighing them down excessively.
  • Apply by gently unravelling each curl to guarantee even coverage — never work on tangled curls.
  • The naturally more open cuticle of curly hair facilitates pigment penetration — results are often more intense and faster to develop.
  • Rinse carefully and redefine curls immediately after rinsing, before the fibre begins to dry.

Strategy for a Uniform Result: Roots vs Ends

On long hair, colour can differ slightly between roots and ends. Ends are often more porous (bleached by sun, dried by heat) and may take colour more intensely. Some adjustments:

  • If your ends always take stronger: apply to the lengths 15–20 minutes after the roots.
  • If your roots consistently take less well: simultaneous application as standard.
  • For a natural-looking result: a slight root-to-end graduation (roots slightly darker) is actually flattering and naturally occurs with untreated hair.

Frequently Asked Questions

Do I need the 2-step method on long hair even if I have few grey hairs?
No. The 2-step method depends on the percentage of grey, not the length. With fewer than 30% grey hairs, the 1-step method is sufficient regardless of length.

Will rinsing plant-based paste from long hair damage it?
No — provided you rinse gently with a wide-tooth comb. Wet hair is more vulnerable to breakage, so avoid rough handling and forced detangling. Work patiently section by section.

How do I stop the paste dripping during processing?
Make the paste slightly thicker (less water), apply a strip of cotton wool along the hairline before pinning up, and use a thermal cap to contain the heat. The paste should be firm enough to stay in place once applied.

Our Recommendation

Long and thick hair colours beautifully with plant-based powder — the technique simply requires more preparation and rigour. Calculate your quantities precisely (more is better than not enough), work in sections, and take the time the rinsing requires. The result — uniform colour from roots to ends, with volume and shine enhanced by plant tannins — is well worth the additional investment of time. Browse the full Tresse Paris range to find the shade best suited to your natural base.

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