Why does the spectral band matter?

A photoinitiator absorbs in a narrow range. If the radiometer band misses it, the dose figure is unrelated to cure.

Is low intensity for longer the same dose?

The dose matches and the cure may not. Surface cure in air depends on peak irradiance, so a weak long exposure can leave a tacky surface.

What dose margin should I run?

Enough to cover lamp decline between checks, usually 20% or more. A line set at bare target is undercured before the next measurement.

My dose is on target but the part is tacky. Why?

Almost certainly oxygen inhibition rather than dose. Higher peak irradiance, nitrogen inerting or a formulation change fixes it; more dose at the same intensity does not.

Finishing calculator

UV Dose Calculator and Cure Margin

Turn a radiometer reading and an exposure time into the dose a part receives. Enter irradiance, exposure, the datasheet target and the cure-zone length.

What this calculator does

Convert irradiance and exposure into delivered UV dose and compare it with the material target.

Formula used

UV dose = irradiance × exposure time
Dose as % of target = delivered dose ÷ target × 100
Exposure needed = target ÷ measured irradiance
Fastest belt speed = cure-zone length ÷ exposure × 60
Dose shortfall = max(target − delivered, 0)

Inputs explained

Measured Irradiance at Part: Radiometer reading at the part, in the target band.
Exposure Time Under UV: Seconds a point on the part spends under UV.
Material Cure-Dose Target: Datasheet dose, in a named spectral band.
Effective Lamp Cure-Zone Length: Useful cure-zone length along the direction of travel.

How to use the result

Best suited to commissioning a line against a datasheet, checking whether an aged lamp still delivers, finding the fastest speed a cure tolerates.
Surface dose only; pigmented or thick films receive less at depth. Does not model oxygen inhibition, which can leave a tacky surface. Not cure verification; gel content or a rub test is evidence.

Common questions

Why does the spectral band matter? A photoinitiator absorbs in a narrow range. If the radiometer band misses it, the dose figure is unrelated to cure.
Is low intensity for longer the same dose? The dose matches and the cure may not. Surface cure in air depends on peak irradiance, so a weak long exposure can leave a tacky surface.
What dose margin should I run? Enough to cover lamp decline between checks, usually 20% or more. A line set at bare target is undercured before the next measurement.
My dose is on target but the part is tacky. Why? Almost certainly oxygen inhibition rather than dose. Higher peak irradiance, nitrogen inerting or a formulation change fixes it; more dose at the same intensity does not.

Related guides

Last reviewed 2026-10-01.