Ink chemistry and pigment selection for UK tattoo artists

Tattoo ink isn't one thing. It's a complex chemistry of pigment (the colour particles), carrier (the fluid that suspends them), and additives (preservatives, surfactants, viscosity modifiers). Different pigments behave differently, they age differently, react differently, are restricted differently under UK REACH from 30 December 2025. This guide describes the chemistry at a working-artist level and how it shapes 2025-26 pigment selection.

The basics, what's in a tattoo ink

A typical commercial tattoo ink contains:

Pigment (~10-25% by mass)

The colour particles themselves. Different pigment classes:

Carbon black, the dominant black pigment. Made from bone char, vegetable char, or synthetic processes.
Iron oxides, red, brown, yellow shades. Inorganic, often used in PMU for natural earth tones.
Titanium dioxide, white pigment, also used to lighten other colours. Nano-particle form now on regulatory watch.
Phthalocyanine pigments, green and blue (Pigment Green 7, Pigment Blue 15:3), the colourants most contested in REACH discussion.
Azo dyes, many of the bright reds, oranges, yellows. Some can release aromatic amines (restricted under REACH).
Quinacridone pigments, magentas, deep reds.
Other organic pigments for specific shades.

Carrier (~50-70%)

The fluid that holds pigment in suspension:

Water (the dominant base in modern inks).
Witch hazel, historic ingredient, antimicrobial.
Ethanol or isopropanol, antimicrobial preservative.
Glycerin or propylene glycol, viscosity, suspension.

Additives

Surfactants to keep pigment in suspension.
Preservatives, historically methylisothiazolinone or similar, now scrutinised under REACH for sensitisation risk.
pH stabilisers.

What UK REACH 30 December 2025 actually restricts

The UK REACH restriction decision published 30 December 2025 limits substances of concern. Broadly:

CMR substances (carcinogenic, mutagenic, reproductive toxic), strict low limits.
Skin sensitisers, concentration limits below recognised sensitisation thresholds.
Specific metals: chromium VI, nickel, lead, cadmium, arsenic, mercury, antimony, beryllium, trace-level limits.
Aromatic amines released by certain azo dyes, restricted.
Methanol, concentration limits.
Specific colourants by CAS number: Pigment Blue 15:3 and Pigment Green 7 are in scope at the 0.1% limit, with no special or longer transition and no derogation.

For the GB/NI split under the Windsor Framework, NI tracks EU REACH 2020/2081. The substantive limits are now closely aligned, though governance differs.

See UK REACH for tattoo inks for the full legal picture.

What this means for pigment selection

The practical purchasing reality:

Black inks

Carbon-based blacks are largely unaffected by REACH restrictions.
Quality varies by particle size, dispersion, carrier formulation.
Premium blacks (Sumi, Solid, Eternal Lining Black, Quantum Coal Black, etc.) typically deliver more consistent line work and pack densities.

Red inks

Historically the most allergy-prone colour family. Modern UK reds:

Mostly azo organic pigments, quinacridones and naphthols.
Cinnabar (mercuric sulphide) historically used, now banned.
Some 2026 azo reds still trigger delayed Type IV hypersensitivity in sensitised individuals, see allergic reactions and red flags.
Specific REACH-restricted azo dyes that release aromatic amines are no longer compliant.

Blue and green inks

Phthalocyanine blue 15:3 and green 7, the politically-contested pigments. Defra rejected the proposed derogation, so both are in scope under UK REACH with no special or longer transition window.
Alternatives include other phthalocyanine variants and some inorganic options.
Buy from compliant suppliers with documentation showing the specific pigment is on the permitted list.

Yellow inks

Historic cadmium yellows, banned.
Modern azo organic yellows, many compliant; some are photoallergic in sensitised individuals.
Lightfastness an ongoing issue, yellows fade fastest of most colour families.

White inks

Titanium dioxide, nano-particle form on regulatory watch in the EU; UK position broadly aligned.
Used both as standalone white and as lightener for other colours.
Some healing issues, white can shift toward grey or yellow over time depending on formulation.

Cosmetic / earth-tone PMU pigments

Iron oxide-based in most cases.
Common allergens minimised in modern PMU formulations.
Often loaded for initial bright colour and aged-result tone.

Pigment behaviour over time

Tattoo pigments don't stay where you put them, and they don't stay the same colour. Working knowledge:

Migration / spread (blowout)

Pigment placed too deep migrates into the fat layer and spreads. Caused by:

Too-deep needle insertion.
Excessive pressure or speed.
Specific anatomical areas where skin is thinner.

Not a chemistry issue, a technique issue. But the result is visible and permanent.

Fading

Causes:

UV exposure breaks down most organic pigments over years.
Skin turnover sloughs the upper layers.
Immune-driven pigment dispersion over decades.
Yellow and orange fade fastest; black and dark blue most stable.

Aftercare advice, sunscreen on tattoos, significantly extends colour life.

Pigment shifts

Some pigments shift colour as they age:

Some blacks shift toward green or blue-grey over decades.
Some reds shift toward orange.
SMP pigments can warm or cool over years depending on formulation.

This is partly chemistry (decomposition products), partly physics (UV breakdown), partly biology (immune clearance preferentially of certain particle sizes).

Allergic reactions developing over time

Sensitisation can develop months or years after the original tattoo.
Specific pigment is implicated in many cases, most commonly red.
Trigger can be unrelated exposure (henna dye, hair dye, specific cosmetics) that primes the immune response.
No patch test reliably predicts delayed sensitisation, see allergic reactions and red flags.

COSHH and ink storage

Under the Control of Substances Hazardous to Health Regulations 2002:

COSHH risk assessment for every ink in your kit.
Safety Data Sheets (current, UK/GB CLP format) for each product.
Storage in original labelled bottles, away from heat and light.
Expiry tracking, expired inks shouldn't be used; many manufacturers specify 2-3 year shelf life from manufacture.
Contamination prevention, never recap a bottle with a contaminated tip; use disposable ink caps and discard between clients.

The "do you really know what's in it?" reality

The blunt 2026 working reality:

Manufacturer-supplied SDS is the documentation the law requires you to hold.
Independent verification (lab testing of specific batches) sometimes shows deviation from the SDS, see supplier audit framework.
You as the artist are the immediate point of accountability to the client.
COSHH and reasonable-care discipline require you to take supplier documentation seriously but not blindly.

The InkKiln supplier-audit position (per the research brief D19): spot-check SDS and CoA documentation on 3-5 UK suppliers before publishing ink guides. Operationally, the same principle applies to your own studio, periodically verify what your suppliers tell you against independent sources.

Colour mixing and matching

Many artists mix inks at the workstation for specific shades. Considerations:

Mix at point of use, disposable cap, single-use.
Don't return mixed ink to original bottles.
Record the mix proportions if you're trying to reproduce the colour later.
Use the same manufacturer's lines where possible, different chemistries can react unpredictably.
Test on synthetic skin or scrap first for complex mixes.

What this guide cannot do

Ink chemistry is detailed and supplier-specific. Specific pigment regulatory status changes; check current REACH text.

Information, not advice. For your situation, source from UK REACH-compliant suppliers with current SDS and CoA, maintain a COSHH risk assessment, and verify independently if a specific supplier or product gives you any concern.