Specialty inks: metallics, fluorescents, glow and UV, minus the mystique

Metallic inks

Metallic inks carry actual metal flake pigment (typically aluminium for silvers, brass alloys for golds) suspended in the vehicle. The shine comes from flakes lying flat and reflecting; that is why metallic ink loves smooth coated stock and a heavy deposit, and why screen printing, with its thick ink film, renders metallics better than a thin offset film (see screen printing explained). It is also why a metallic ink never reaches the mirror finish of a stamped foil, which is a deposited metallised layer rather than flakes in a binder; if the brief says "mirror", the answer is foil, not ink. In the Australian market, water-based screen metallics are available locally: Permaset lists metallic colours in both its textile and paper/board (Permaprint) ranges.

Fluorescent inks

Fluorescent pigments absorb ultraviolet light and re-emit it as visible light, which is why a fluoro orange appears brighter than its surroundings in daylight and lights up under a UV lamp. The trade-offs are well known to anyone who has run them: fluorescent pigments are less lightfast than conventional ones and their brilliance depends on the deposit and the ground, so they perform best over white with a generous film. Permaset's glow colours, for example, are described by the manufacturer as fluorescing under UV, with the range covering yellow through green.

Phosphorescent (true glow-in-the-dark)

Different chemistry from fluorescence: phosphors charge under light and keep emitting after the light goes, which is what safety signage and novelty work want. It exists as a screen ink line locally (Permaset lists a phosphorescent green among its speciality inks). Charge time, brightness and decay are formulation-specific; get them from the maker's data sheet for the actual product quoted, not from a category generalisation.

UV-cured inks and varnishes

"UV" on a quote usually means the curing method, not an effect: inks and varnishes that polymerise instantly under UV lamps instead of drying by absorption and evaporation. Instant cure means printing on non-absorbent substrates, sharper dots, and no spray powder; it is also the chemistry behind spot UV effects. Uncured UV chemistry is a skin sensitiser, which is a handling matter, and cured versus uncured state matters for waste handling too; the governing framework in an Australian shop is WHS law and the product's safety data sheet, per Safe Work Australia's hazardous chemicals code of practice.

The compliance questions that actually come up

• Is there a dedicated Australian printing-ink standard? Not that we can find, and we have looked: the applicable framework is WHS law (SDS, labelling, controls) via the Safe Work Australia model code. Be suspicious of any supplier citing "the Australian ink safety standard" without a document number; ask for the SDS instead.
• Food packaging: ink migration into food is a real compliance surface; low-migration ink systems exist for exactly this, and a packaging job's ink spec should be part of the food-contact conversation with your converter and ink supplier, documented in writing.
• Sustainability claims: "eco" effects inks range from genuinely water-based systems with published ingredient exclusions (the Permaset pages, for instance, state phthalate-free, water-based formulations) to marketing. The test is always the same: is the claim on a published data sheet you can link?