PI-WIKI-CHEM-04 · Pigment Science · reviewed 2026-10-27
Ink Chemistry & Pigment Particles
Critical numbers
Optimal Particle Size (D50)100–250 nm
Reliable Macrophage RetentionAbove about 50 nm diameter
Lymphatic Clearance Risk< 50 nm (nano range)
Carrier pH Target6.5–8.0
Viscosity Range (optimal wicking)500–2,000 cP
Lightfastness ReferenceASTM D4303 categories I–II (no tattoo-specific standard) [3]
Sterility Assurance LevelSAL 10⁻⁶ (usually gamma irradiation)
Nickel Limit (Entry 75, Appendix 13)0,0005 % w/w (5 mg/kg) [1]
Benzo[a]pyrene (PAH) Limit< 0.0000005% w/w (0.005 mg/kg); the 0.00005% generic CMR limit is not the benzo[a]pyrene one
Other carcinogenic PAHs (each)0,00005 % w/w (0.5 mg/kg) individually; Entry 75 sets no sum-of-eight limit
Aromatic Amine Limit (azo)0,0005 % w/w (5 mg/kg) each, for the amines named in Appendix 13
Banned: Blue 15:3 (PB15:3)EU Regulation 2020/2081, restricted since 4 Jan 2023 [1]
Do not
- Using inks that contain banned EU 2020/2081 pigments on EU-resident clients
- Treating "vegetable-based" or "organic" marketing claims as safety guarantees
- Diluting ink with tap water
- Ignoring sedimentation as normal
- Ignoring the storage and use-by rules once a bottle is open
- Not verifying CoA/batch documentation
Applicable standards
- European Union — EU Regulation (EU) 2020/2081
- United States — FDA 21 CFR Part 700
- ASEAN & Asia-Pacific — Thailand