Thank you Bill for seeing some potential in all of this. The light meter I bought is $180 new, but I found it on eBay for $40. Not bad, and there are lesser units out there; specifically those aimed at sunburn/skin-cancer prevention.

Loris, certainly working from an integrator isn't empirical, but few people are using these. Instead they're probably using fluorescent bulbs, mercury lamps, the sun, etc, and to use these you must rely on experience, as bulbs age & the wind blows. There's absolutely nothing wrong with that, and obviously it's been working pretty well for the last 160 years.

But the fact that alt.process printers can't say, on average we need X millijoules/cm² of UV to expose this process, seems like a gap in our understanding (and perhaps nothing more). Dependant on the factors you mentioned, certainly there will be wide variability, but wouldn't you like to know the extremes?

I don't disagree with your points at all, I just don't see the point of being so critical. Scientists the world over study the most minute minutia imaginable, and after a while it all adds up to something meaningful.