Body Art Glossary

The REACH regulation annex that lists restrictions on the manufacture, placing on the market, and use of certain dangerous substances. Entry 27 restricts nickel in post assemblies (≤0.2 µg/cm²/week) and articles intended to come into direct and prolonged skin contact (≤0.5 µg/cm²/week). Applies to all body jewelry sold in the EU.

An electrochemical process that grows a controlled, thickened TiO₂ oxide layer on the surface of titanium or niobium. The oxide thickness determines the visible colour via thin-film interference. Adds a durable, biocompatible colour layer without pigments, dyes, or coatings.

The systematic measurement of the human body — the clinical discipline underpinning correct jewelry sizing. Includes tissue depth measurement, anatomical site variation, and the 20% heal-room rule. Individual measurement is always required; population averages are planning references only.

The sharpness of the needle tip. Professional-grade piercing needles have an apex radius of ~2.5 μm or less. Substandard needles with larger apex radii (>5 μm) cause more tissue crushing than cutting, increasing trauma and healing complications.

The REACH regulation provision requiring suppliers to inform consumers, within 45 days of request, whether any article they supply contains an SVHC above 0.1% w/w. The consumer does not need to justify the request. The response must include the SVHC name and safe-use information.

The ASTM International specification for wrought Ti-6Al-4V ELI (Extra Low Interstitial) titanium alloy for surgical implant applications. The gold-standard body jewelry material: contains no nickel, forms a self-healing TiO₂ passivation layer.

The ASTM specification for wrought 18Cr-14Ni-2.5Mo stainless steel, vacuum arc remelted (VM = Vacuum Melted). The "LVM" variant has reduced sulphide inclusions and refined grain structure producing lower nickel ion release than standard 316L. Contains 12–14% nickel.

A pressure chamber that uses saturated steam at elevated temperature and pressure to destroy all microbial life, including bacterial endospores. The standard method for sterilizing reusable body art instruments.

Synthetic organic colourants widely used in tattoo inks. Under UV exposure or laser treatment, certain azo dyes can cleave into aromatic amines — some of which are carcinogenic. EU 2020/2081 restricts aromatic amines derived from azo dyes to ≤0.0005%.

A sterilization cycle using a pre-vacuum pump to actively remove air from the chamber and from inside porous materials. Required for wrapped instruments, textile packaging, hollow items, and porous loads — the correct choice for most body art studios using pouched instruments.

A proprietary polypropylene random copolymer (PP-R) developed by Poli International for body jewelry. Biocompatible per ISO 10993, contains zero nickel, flexural modulus ~1,200 MPa, and can be autoclaved. Designed as a flexible, metal-free alternative for initial piercings, MRI-safe retention, and long-term wear.

A standardized preparation of Geobacillus stearothermophilus spores used to verify that an autoclave cycle actually achieved sterilizing conditions. Weekly testing is the minimum professional standard. A negative (no growth) BI confirms kill.

Disease-causing microorganisms present in human blood that can cause disease in humans. The three primary concerns in body art are Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), and Human Immunodeficiency Virus (HIV). HBV can survive on surfaces for ≥7 days.

A tattoo defect where ink spreads beyond the intended line into the subcutaneous fat layer, creating a blurred, hazy appearance. Caused by penetrating too deeply (past the dermis into the hypodermis) or incorrect needle angle. Permanent; laser removal is the only correction.

A diagnostic test that verifies the pre-vacuum pump is effectively removing air from the autoclave chamber. Performed daily on B-cycle autoclaves before any load is processed. Air pockets prevent steam contact and cause sterilization failure.

An ultra-fine tattoo needle configuration using 0.20 mm wire diameter instead of the standard 0.35 mm. Produces finer detail but delivers less ink per puncture, requiring slower hand speed. Named after the insect-pin analogy of extreme thinness.

The liquid component of tattoo ink that suspends pigment particles and delivers them to the dermis. Typically a mixture of water, glycerin, isopropyl alcohol, and witch hazel. The carrier evaporates or is absorbed after implantation, leaving pigment particles trapped in the dermis.

A unique numeric identifier assigned to every chemical substance described in the open scientific literature. Used alongside CI numbers in SDS documentation for tattoo ink compliance verification — different pigments with the same CI can have distinct CAS numbers depending on the specific chemical form.

Tissue damage that occurs when jewelry is too thin relative to the piercing channel width, causing it to slowly cut through tissue like a wire through cheese. The risk threshold is reached when jewelry diameter is smaller than channel width by >0.5 mm.

A color-change strip or marking placed inside each sterilization pouch that visually confirms exposure to sterilizing temperature. Required on every single cycle, inside each pouch. Does not confirm sterility — only a BI does that.

The international standard identifier for pigments and dyes (e.g., CI 74160 = PB15:3). Used on Safety Data Sheets (SDS) and pigment certificates. The regulatory identifier for compliance checking against EU Annex II restricted substances.

A high-strength alloy (~28% Cr, ~6% Mo, balance Co) with excellent passivation and fatigue resistance. However, chromium and cobalt ion release under wear conditions is a concern. PVD coating is required for REACH nickel compliance on fresh piercings.

A measure of a light source's ability to reveal colours accurately compared to natural daylight, on a scale of 0–100. Body art studios require CRI ≥ 90 for accurate pigment colour assessment during tattooing and for correctly identifying tissue colour changes during piercing.

The time required at a given temperature to reduce a microbial population by 90% (one log). For G. stearothermophilus at 121°C, D ≈ 1.5 minutes. Used to calculate total cycle lethality.

The median particle diameter in a pigment distribution — 50% of particles are smaller, 50% larger. For tattoo ink, optimal D50 is in the sub-micron range to ensure suspension stability and predictable dermal distribution.

The appointment to replace initial (longer) jewelry with a shorter, properly fitted piece after swelling has resolved (typically 2–8 weeks depending on site). A long post in a healed piercing creates leverage trauma, gum recession, tooth chipping, and hypertrophic scarring.

The EU agency responsible for implementing REACH, CLP, BPR, and other chemicals legislation. Maintains the Candidate List of SVHCs, the SCIP database, and the Classification and Labelling Inventory. The primary regulatory authority for tattoo ink and body jewelry chemical compliance in the EU.

An electrochemical finishing process that removes a thin layer of metal from the surface, preferentially dissolving microscopic peaks to produce a mirror-smooth surface. MIM body jewelry electropolished from as-sintered Ra <0.8 μm to Ra <0.1 μm — the standard for implant-grade surface finish.

The minimum nickel ion dose required to trigger a visible allergic reaction in an already-sensitized individual. For sensitized individuals, the elicitation threshold can be as low as 0.5 µg/cm²/week — the same as the REACH release limit for piercing jewelry.

The European standard test method for determining nickel release from post assemblies inserted into pierced parts of the human body. Simulates extended skin contact using artificial sweat solution and quantifies nickel ion release via ICP-MS.

The equivalent sterilization time at 121°C, accounting for all temperature variations during a cycle. A standard B-cycle at 134°C delivers F₀ ≈ 15–20 minutes of equivalent lethality.

The metal-powder-and-binder mixture that is injected into the MIM mould. Typical composition: 55–65% metal powder by volume (particle size 5–20 μm), balance thermoplastic binder. The binder is later removed through thermal or solvent debinding before sintering.

The healed tissue channel that forms around a piercing. During healing, epithelial cells migrate inward along the jewelry surface from both entrance and exit, eventually meeting to form a continuous protective lining. This process takes months even after the surface appears healed.

A six-point clinical classification of skin colour and UV response (Type I = pale, always burns, never tans; Type VI = deeply pigmented, never burns). Affects tattoo ink visibility, laser removal safety (melanin competes for laser energy), keloid risk, and pigment selection.

A measure of a material's stiffness when bent — the ratio of stress to strain in flexural deformation, expressed in MPa. BioFlex has a flexural modulus of ~1,200 MPa. Lower values mean more flexibility: BioFlex is approximately 40× more flexible than 316L stainless steel (~193,000 MPa).

The energy delivered per unit area by a laser pulse, measured in J/cm². Higher fluence fragments more pigment but increases risk of thermal damage to surrounding tissue. The therapeutic window balances pigment destruction against skin safety.

Accelerated corrosion that occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte (body fluids). The less noble metal releases ions at an accelerated rate into the healing wound. Never mix metal types in a single piece contacting a fresh piercing.

The American Wire Gauge system used to specify piercing jewelry thickness. Counterintuitively, smaller gauge numbers indicate larger diameters: 18g = 1.0 mm, 14g = 1.6 mm, 00g = ~9.3 mm. Originally a wire-drawing standard; now the universal piercing industry convention.

The reference spore-forming bacterium used for biological indicator testing in steam autoclaves. Its spores are the most heat-resistant relevant to steam sterilization; if they are killed, all other organisms in the load are also dead.

A progressive and irreversible condition caused by prolonged exposure to vibrating tools. In body art, coil tattoo machines transmit vibration directly to the artist's hand. The ISO 5349-1 standard defines an Exposure Action Value (EAV) of 2.5 m/s² and an Exposure Limit Value (ELV) of 5.0 m/s² for an 8-hour shift.

The extra length added to initial piercing jewelry to accommodate post-procedure swelling. The rule: soft tissue sites require 20–30% additional length beyond resting tissue measurement; oral sites require 40–50%; cartilage requires 15–20%.

The first stage of wound healing: blood vessel constriction and platelet aggregation forming a temporary plug, followed by fibrin mesh formation. Begins immediately upon injury and lasts minutes to hours.

A post-sintering process that applies high temperature (900–1,100°C for 316L) and high isostatic argon gas pressure (100–200 MPa) to eliminate residual internal porosity. HIP pushes MIM density above 99.2% of theoretical — approaching aerospace structural quality.

A raised scar that stays within the original wound boundary, caused by excess collagen production during healing. Common on piercings subject to mechanical irritation (movement, pressure). Usually resolves with removal of the irritation source; distinguished from keloid by its self-limiting nature.

The analytical technique that provides a batch-specific elemental composition certificate for metal jewelry. The only acceptable proof of actual material composition. Generic declarations without a batch-specific ICP-MS certificate have no regulatory validity.

A material specification (not a marketing term) referencing ASTM or ISO standards for materials proven safe for permanent implant in the human body. ASTM F136 titanium and ASTM F138 316LVM are implant-grade. "Surgical steel" without a specification number is not.

The second stage of wound healing: increased blood flow, immune cell recruitment, and debris clearance. Normal duration for a fresh piercing is 3–5 days. Extended inflammation beyond 7–10 days may indicate infection, material sensitivity, or mechanical irritation.

The international standard series for biological evaluation of medical devices. ISO 10993-1 covers general evaluation and testing, ISO 10993-5 covers cytotoxicity, ISO 10993-10 covers sensitization and irritation, ISO 10993-12 covers sample preparation. Biocompatible body jewelry materials should meet the relevant parts of this standard.

An overgrowth of scar tissue that extends beyond the original wound boundary. Genetically linked; more common in Fitzpatrick skin types IV–VI and certain anatomical sites (chest, shoulders, earlobes). Distinguished from a hypertrophic scar which stays within wound boundaries.

A clinical scoring system used to estimate the number of laser sessions required to remove a tattoo. Scores six variables: Fitzpatrick skin type, tattoo location, ink colours, ink density, scarring/tissue change, and layering (cover-up or not). Higher scores predict more sessions needed.

A manufacturing process combining plastic injection moulding's shape-making capability with powder metallurgy's material flexibility. Metal powder is mixed with a polymer binder to form "feedstock," injected into a mould, then the binder is removed and the part sintered to near-full density. Applied to body jewelry by Poli International in the 2014 Sanford-Poli trials.

The gradual movement of a piercing from its original placement, caused by uneven pressure distribution, incorrect angle, or insufficient tissue depth. Distinguished from rejection: migration may stabilize; rejection continues until jewelry is expelled.

A sterilization cycle that uses gravity displacement (steam pushes air out from the bottom). Only suitable for naked solid instruments with no packaging and no hollow lumens. Common in cheap tabletop units but insufficient for professional studio use.

A solid-state laser using neodymium-doped yttrium aluminium garnet crystal, operating at 1064 nm (near-infrared). The 1064 nm wavelength is the primary tool for black and dark tattoo ink removal because it penetrates deeply and is well-absorbed by carbon-based pigments while sparing melanin. Frequency-doubled 532 nm targets red and orange pigments.

The graduated point profile of a piercing or tattoo needle that controls how the needle enters tissue. Long tapers (lower taper angle) reduce insertion force and tissue trauma. Short tapers concentrate force at the tip, producing a larger entry wound for the same gauge.

The rate at which nickel ions leach from a metal object into a surrounding fluid (simulating body fluids), measured in µg/cm²/week. The EU REACH Annex XVII Entry 27 limit for body jewelry in pierced skin is ≤ 0.5 µg/cm²/week, tested to EN 1811.

The process by which repeated or prolonged exposure to nickel ions triggers an immune system response, creating memory T-cells specific to nickel. Once sensitized, even very low nickel exposure can trigger an allergic reaction (allergic contact dermatitis). Affects an estimated 10–20% of the general population, higher in pierced individuals.

A pure elemental metal (Nb, atomic number 41) that forms a Nb₂O₅ passive layer comparable in stability to TiO₂. Contains no nickel. Naturally anodisable to a wide range of colours. Minimum purity 99.9% for body jewelry. An implant-grade choice often overlooked.

A class of organic compounds, some carcinogenic, that can be present as impurities in carbon black tattoo pigments. The EU 2020/2081 regulation limits benzo[a]pyrene to ≤0.00005% (0.5 ppm) and the sum of 8 named PAHs to ≤0.0005% (5 ppm) in tattoo inks.

The spontaneous formation of a thin, stable oxide layer at a metal surface that acts as a physical barrier between the substrate and body fluids. Titanium forms TiO₂ (reforms in milliseconds after damage); steel forms Cr₂O₃. This layer is what makes implant-grade metals biocompatible.

A diagnostic procedure where small amounts of potential allergens (including nickel) are applied to the skin under occlusive patches for 48–96 hours to determine whether a contact allergy exists. The standard protocol for confirming nickel allergy before selecting body jewelry materials.

The process by which immune cells (macrophages) engulf and attempt to digest foreign particles, including tattoo pigment. Pigment particles below ~0.1 μm can be cleared via the lymphatic system; larger particles remain trapped in dermal macrophages, which is what makes a tattoo permanent.

A newer generation of tattoo removal laser with pulse durations in the picosecond range (10⁻¹² seconds), approximately 1,000× shorter than Q-switched nanosecond pulses. Produces more efficient pigment fragmentation via photoacoustic (shockwave) rather than photothermal effect, potentially requiring fewer sessions.

A copper phthalocyanine blue pigment banned in tattoo inks and permanent make-up under EU 2020/2081. Present as a component in many blue, green, and purple mixtures. Previously the most common blue in professional tattoo inks.

A chlorinated copper phthalocyanine green pigment banned under EU 2020/2081. Present in many green and teal formulations. Banned alongside PB15:3 because phthalocyanine pigments cannot meet the purity requirements of the regulation.

The third stage of wound healing: new tissue formation including collagen synthesis, angiogenesis (new blood vessel growth), and epithelial cell migration. For piercings, this is when the fistula begins to form. Surface epidermal closure typically occurs within 2–4 weeks for most soft-tissue sites.

A fully fluorinated polymer with the lowest coefficient of friction of any solid (~0.05–0.10) and exceptional chemical inertness. USP Class VI biocompatible. Used in body jewelry for its self-lubricating surface and complete resistance to body-fluid absorption. Autoclavable.

A laser that delivers energy in extremely short, high-power pulses (nanosecond range, ~5–20 ns) by storing energy in the laser cavity and releasing it in a single rapid burst. The short pulse duration allows pigment particles to heat and fragment before heat spreads to surrounding tissue.

The progressive expulsion of jewelry by the body as it treats the object as a foreign body. The immune system slowly pushes the jewelry toward the skin surface until it exits. Surface piercings are highest risk; adequate tissue depth and correct angle are the primary prevention.

The final and longest stage of wound healing: collagen fibers reorganize and strengthen. For a piercing, the fistula wall matures and strengthens over 6–24 months depending on site. Cartilage piercings may require 12+ months for full maturation.

A "specific" sterilization cycle designed for particular load types defined by the manufacturer, typically solid, unwrapped instruments only. Cannot reliably sterilize porous or hollow items. Not appropriate for pouched jewelry.

The EU database for Substances of Concern In articles as such or in complex objects (Products), maintained by ECHA. From January 2021, any product placed on the EU market containing an SVHC above 0.1% w/w must be notified to SCIP. Applies to body jewelry, tattoo inks, and studio consumables.

A standardized document providing information on the properties, hazards, safe handling, and regulatory status of a chemical substance or mixture. Required for professional-use products including tattoo inks and sterilization chemicals. Section 3 lists hazardous ingredients with CAS numbers — the bridge between pigment formulations and the REACH SVHC Candidate List.

A puncture-resistant, leak-proof, labeled container for disposal of used needles, blades, and other sharp items. Must meet applicable regulatory standards (e.g., OSHA, EU Directive 2010/32/EU). "Never recap by hand" is a universal rule; single-handed scoop method only when recap is necessary.

A scale measuring the resistance of a material to indentation. Medical-grade silicone for body jewelry typically has Shore A hardness of 30–70. Lower values are softer and more flexible but less durable; higher values hold shape better under pressure.

The process of heating compacted metal powder below its melting point so that particles bond at their contact points through atomic diffusion. In MIM, sintering at ~1,300–1,380°C in a hydrogen atmosphere achieves 96–99% density and produces ~15–20% linear shrinkage from the as-moulded dimensions.

The probability that a single item remains non-sterile after a sterilization cycle. SAL 10⁻⁶ means at most one survivor per million items processed — the required standard for instruments that penetrate skin.

The arithmetic average deviation of a surface from its mean line, measured in micrometres (μm). Ra ≤ 0.4 μm is recommended for initial piercing jewelry contact surfaces. Rougher surfaces provide anchoring sites for bacterial biofilm and concentrate stress at asperities, accelerating corrosion.

A chemical substance identified under EU REACH as having serious and often irreversible effects on human health or the environment (carcinogenic, mutagenic, reprotoxic, persistent/bioaccumulative/toxic, or endocrine disrupting). If a product contains an SVHC above 0.1% w/w, suppliers must provide safety information to consumers within 45 days of request (Article 33).

A smooth, graduated rod used to gradually stretch a piercing channel to accommodate larger-gauge jewelry. Also refers to the angle profile of piercing needles (see needle taper). The standard taper range for body piercing is 18g through 00g.

The ceramic oxide layer that forms on titanium surfaces. On implant-grade titanium, this layer is ~2–7 nm thick naturally and self-heals within milliseconds of mechanical damage. Anodization thickens it to 30–300 nm to produce interference colours.

A cleaning method using high-frequency sound waves in an enzymatic detergent bath to remove debris from joints, threads, and internal surfaces that manual scrubbing cannot reach. The preferred pre-cleaning method before autoclaving.