UV Light Recommendation

[BruceRC]

All

What recommendations do you have for UV lights? One of my friends wants to build a UV box and he is unclear of the bulb type that he should use.

Also- if you have any suggestions on how high the bulbs should be over the contact print frame, please provide that info.

Thanks!


Bruce

[tom_micklin]

All

What recommendations do you have for UV lights? One of my friends wants to build a UV box and he is unclear of the bulb type that he should use.

Also- if you have any suggestions on how high the bulbs should be over the contact print frame, please provide that info.

Thanks!


Bruce

Hi,
I bought mine from this site http://www.eepjon.com/
But there is also a lot of information on bulbs, etc. plus a Build-It-Yourself kit.
If you check out the UV FAQ, I think you'll find the information you're looking for on distance from the bulbs to the frame.
Hope this helps,
Tom

[BruceRC]

Tom

Thanks for the info. My friend and I also found some very good info in the "Platinum and Palladium Printing" book by Dick Arentz.

Bruce

[michael mutmansky]

Bruce,

Generally, the BL lamp (blacklight, not BLB-blacklight blue) os considered the best lamp for the iron processes. It's possible to us aquarium lamps (AQ or AQA) as well, and some of those are HO and VHO lamps, which will speed the printing time. You need special ballasts for HO and VHO lamps, though.

As for distance, it's not critically important, but you generally want the lamps as close as you can get to the print frame glass within reason. Most people put theirs about 2-3" away. It's generally better to be closer rather than farther.

Space the lamps as close together as possible. for T12 lamps, most people put them at 2" O.C., which leaves a 1/2" gap between the lamps. Any closer and you may have problems getting the lamps in and out of the sockets.

Make sure the lamps extend beyond the desired printing area by at least 4" or so on each edge, or you may experience some exposure falloff into the edges.

Put a good reflector behind the lamps. Use a metal one, and tie it into the ground. Make sure you have good ventilation on the lamps and the ballasts, as the assembly will heat up considerably, and the heat will reduce the output of the lamps, and possibly shorten lamp and ballast life.


---Michael

[sanking]

I have an article on printing with UV light sources at http://unblinkingeye.com/Articles/Light/light.html

The article was written a number of years ago but most of the information is still relevant.

The BL tube is the best all-around tube for printing with alternative processes IMO, though if you are printing only with the iron processes one could make a case for the SA or AQUA.

I have found some real peculiarities in printing with the iron processes. For example, the only difference between the BL and BLB tubes is that the latter has a filter that cuts out all light over about 420 nm, and the iron processes clearly have a lot of sensitivity to light over 420 nm. AQUA tubes don't radiate any light below this wavelength, but they print pt./pd. about as fast as BLs. Yet in practice the light over 420 nm seems pretty much wasted with the BL tubes because they don't print much faster than the BLBs. I don't say that as a point of speculation because I have actually compared the printing speed of BL and BLB tubes with a number of alternative processes in the same light fixtures, and the speed advantage of BL is really minimal, less than 1/4 stop.

I actually prefer the BLBs because the strange light highlights every speck of dust on the vacuum glass which makes it easy to keep it spotless. Of course, you should wear UV goggles when you look at the light.

Another consideration in favor of the BLB tubes is that many local store keep them in stock since they are a kind of novelty item, at least in my area of the country. If you want BLs you have to order them, and last time I ordered 48" BL tubes half of them arrived crushed.

Sandy King

[Loris Medici]

Dear Sandy,

What can you say about dichromate processes such as gum or carbon? Do you think light above 420nm can affect speed and contrast of the emulsion in case of dichromated sensitizers?

Thanks in advance,
Loris.

...Yet in practice the light over 420 nm seems pretty much wasted with the BL tubes because they don't print much faster than the BLBs. I don't say that as a point of speculation because I have actually compared the printing speed of BL and BLB tubes with a number of alternative processes in the same light fixtures, and the speed advantage of BL is really minimal, less than 1/4 stop...

[sanking]

Dear Sandy,

What can you say about dichromate processes such as gum or carbon? Do you think light above 420nm can affect speed and contrast of the emulsion in case of dichromated sensitizers?

Thanks in advance,
Loris.

Loris,

If you compare the BL to the BLB tubes I really don't believe that light over 420 nm affects speed and contrast very much, if at all, with the colloid processes. The reason is that the colloid processes have very strong spikes around 360nm, and the spikes over 400 nm are just to weak to have much overall impact. I print with carbon all the time and have tested this by comparing BL to BLB tubes and there just is not very much difference.

On the other hand, if you print with a light source that puts out little or no radiation below 400 nm so that all of the exposing light is over this wavelength then I believe you do see an increase in contrast. You can actually print carbon with a type of tube knowns as the "daylight" tube, and although exposures will be much longer than with BL or BLB, you definitely get more contrast.

Sandy King

[timeUnit]

I built a UV box a while back using 6 Philips Actinic 05 tubes. I've used it for cyanos and gum bichromate. I took a bit of thinking to understand the wiring, as I didn't have so much to go on, but it seems to work fine. I have two 4 inch fans on each side of the "box" to cool things down. It's not really a box though, more like a hood. Or a roof with two walls.

Exposure with cyanos, 8-15 minutes. With gum, 3-12 minutes depending on mix.

[RobertP]

I have an article on printing with UV light sources at http://unblinkingeye.com/Articles/Light/light.html

The article was written a number of years ago but most of the information is still relevant.

The BL tube is the best all-around tube for printing with alternative processes IMO, though if you are printing only with the iron processes one could make a case for the SA or AQUA.

I have found some real peculiarities in printing with the iron processes. For example, the only difference between the BL and BLB tubes is that the latter has a filter that cuts out all light over about 420 nm, and the iron processes clearly have a lot of sensitivity to light over 420 nm. AQUA tubes don't radiate any light below this wavelength, but they print pt./pd. about as fast as BLs. Yet in practice the light over 420 nm seems pretty much wasted with the BL tubes because they don't print much faster than the BLBs. I don't say that as a point of speculation because I have actually compared the printing speed of BL and BLB tubes with a number of alternative processes in the same light fixtures, and the speed advantage of BL is really minimal, less than 1/4 stop.

I actually prefer the BLBs because the strange light highlights every speck of dust on the vacuum glass which makes it easy to keep it spotless. Of course, you should wear UV goggles when you look at the light.

Another consideration in favor of the BLB tubes is that many local store keep them in stock since they are a kind of novelty item, at least in my area of the country. If you want BLs you have to order them, and last time I ordered 48" BL tubes half of them arrived crushed.

Sandy King

What about the AmerGraph ULF-28?

[sanking]

What about the AmerGraph ULF-28?

The AmerGraph ULF-28 is a great UV light that prints a lot faster than a bank of BL tubes.

But the question was about making a unit with tubes as I recall?

Sandy King