UV Curing calculator

UV Ink Cure Speed Calculator

On a UV web press the cure speed is set per ink — heavily pigmented opaques cure slower than spot colors and clear coats cure fastest. This calculator lets a press operator or process engineer back-calculate the press speed in feet per minute that achieves the ink's target dose at the measured irradiance, with a margin sized for film-weight variation. Use it on every makeready instead of relying on the last operator's setpoint.

What this calculator does

  • Solve for the press speed (fpm) at which a UV ink film hits target dose, with a margin for ink film thickness and pigment loading variation.
  • Use it during press makeready and SKU changeover to dial in a starting cure speed instead of running blind off the operator's last memory.
  • Returns a press speed setpoint in ft/min that delivers the ink vendor's target dose at the measured irradiance, with a margin for film-weight variation.

Formula used

  • Press speed (ft/min) = (cure-zone length ÷ 12) ÷ (target dose ÷ measured irradiance) × 60
  • Recommended press speed = press speed ÷ (1 + cure margin)

Inputs explained

  • Ink target dose: From the ink vendor — depends on color, opacity, film weight, and substrate (paper vs film vs metallized).
  • Lamp cure-zone length: Effective UV cure-zone length per cure station, measured with a profiling pass.
  • Cure margin: Headroom for film-weight variation across job; 15–25% typical for process inks, 25–40% for opaque whites.

How to use the result

  • Use on every makeready, after cure station lamp changes, when switching between process color and opaque inks, and when downstream finishing (laminating, foiling) shows poor adhesion that traces to undercure.
  • Single-station math. For multi-cure-station presses (between-station cure), run the calculator per station then take the slowest speed as the press limit. Doesn't model ink chemistry differences across vendors — a switch from one brand of cure-on-film to another may require re-baselining the target dose.

Common questions

  • Why does opaque white cure so much slower? TiO2 in opaque white absorbs and scatters UV strongly, so much less light reaches the bottom of the ink film. Vendors usually quote a target dose 3–5× higher for opaque white than for clear coats. Don't reuse a cure speed across colors — re-run with the right target dose per ink.
  • Calculator wants slower press speed than my supervisor allows — what now? You have a real cure-vs-throughput conflict. Three real moves: increase irradiance (clean lamp, replace if aged), reduce ink film weight (work with the ink rep on a lower-build formulation), or add a second cure station in series. Don't quietly run faster — ink that looks fine often laminates or foils poorly when undercured.
  • How do I know if the ink is actually cured? On press: solvent / MEK rub test (number of double rubs to break the surface), tape test for adhesion, and a cross-hatch on a fresh sample. In the lab: residual photoinitiator measurement or DSC if the ink chemistry is sensitive. If you only have the rub test, do it at every speed change — it's the fastest cure indicator on a press.
  • What about water-based or eb-cure inks? This calc is for UV-cure inks only (free-radical or cationic). Water-based inks cure thermally (oven), and EB cure uses electron beam (different dose math, different spec). Use the appropriate calc for those — UV math doesn't transfer.

Last reviewed 2026-05-12.