uv radiation danger zone

I used to use a bank of four 250 watt incondescent uv curing bulbs for printing and my printing times were around 8 or 9 minutes. If I wanted to burn something in or burn edges or dodge something I was usually in for a minute to 4 minutes of personal exposure. It would burn me very quickly so I would wear UV protection glasses and sun block on my face and long sleeve shirts and golves to avoid exposure.

This last year I built myself a uv florescent bank of ten 22 inch bulbs. For printing it is far more powerful and my times are down to 5 to 7 minutes but I don't detect any affect from personal exposure at all. I have done some edge burning and a little dodging without any protection and it seems harmless. I tried an experiment of putting my toes right up to the bulbs and leaving them there for 5 minutes and it seems to have done nothing at all.

Does anyone know what is the health risk of this type uv exposure. I got the bulbs that have high uv output and are not black lights.

thanks
Dennis

Without knowing what the wavelength of the light is, any guess is a shot in the dark. Exactly which model number of bulbs were burning you and what are the model numbers of the bulbs you are using now. UV ranges from approx 370nm down to 190nm. the shorter the wavelength, the worse it is for you.

From your description, I'd guess the newer bulbs put out UV with a much longer wavelength than the previous ones.

UV radiation exists at wavelengths shorted than 190nm, but it is readily absorbed by air.

Always wear eye protection, you don't want cataracts developing in your eyes.

BTW, I assume "eye protection" can be a pair of UV blocking sunglasses ? I also do the odd dodge & burn; it;s kinda nice to see what one's doing

I did find that it took 6 minutes with my feet right up in the bulbs to get a slight burn. That would have burned the holy beegeezus out of me with the incandescent bulbs. I use UV blocking sun glasses and a large enough card for edge burning that I don't have to get my hands in there.

To be absolutely safe, you can get proper goggles from an optics place like edmunds or thorlabs. Won't cost much. It's *really* important to realize that your pupil reflex won't work for UV exposure: it reacts almost entirely to the light that you see, so you can be looking at a light source and thinking, na that's not bright... while it is frying your eyes. You don't want to have cataract surgery prematurely, so...get the right goggles. Don't trust sunglasses. Anyway if you have the right UV goggles then you will have better vision in the visible region which can be helpful.

There is also skin damage to consider- be sure to limit exposure, and a little skin creme wouldn't be a bad idea if you're working around a UV unit frequently.

Another thing that I'll mention on this topic, which probably is irrelevant for you and most UV users here, but some of these UV units can create a fair amount of ozone and it is important to use them in a well-ventilated area. I use a D2 lamp in the lab and that is a really big concern. I say this because some of us work in smallish darkrooms or light-safe enclosures and it can become an issue with the deeper UV units.

P.S. From a biological standpoint, the region 250-350 nm is the killer.

As someone with very fair skin (and a former redhead before I acquired my "adult plumage"), I have spent a lot of time in dermatologists' offices because of skin damage from UV. They have warned me that UV damage is cumulative. For example, twelve 5-minute exposures to UV from the sun creates the same longterm damage as one continuous hour of exposure. UV lights for alternative processes may less damaging than the sun, but they still will damage your skin. Anyone using processes involving extended, direct expsure to UV lights should seriously consider using sun screen and UV protective glasses. At least consult with a dermatologist. Remember the question that helped me (scared me, actually) to stop smoking: "Is this the one that starts the cancer growing?"

Keith

You could have been doing yourself some serious damage -- more than just sunburning your tissues. Curing bulbs can put out anything from 200 to 400 nanometers, depending on the material they are suppose to cure. The range of 200 to ~280 nanometers is UVC -- that's the range they use to kill things. Plus much of UVC and UVB are not all that effective for alt processes.

The uv florescent bank puts out UVA (~320 to 400 nanometers), which is much safer and more effective for exposing alt processes.

Medical UV curing takes place at almost 400 nanometers.

Glad you switched!

Vaughn