Bjorn,

Is the pcb exposure process sensitive to wavelengths other than those in the UV range?

If so, why not use a standard light source?

If not, I'd find the manufacturer of the blacklight with which you are familiar. Send that manufacturer an email to find the emission spectrum (wavelength vs. power) of the bulb in question. Modify your normal exposure times to account for the power difference between the intended UV source and a blacklight.

Wear sunglasses ;-)

Bruce