UV Bliss

[Jeremy]

I just had to share this because no one I can talk to here cares one whit about a box that produces light which is harmful to your eyes

The box was on for about 30 seconds (the first time ever!) so the bulbs hadn't completely come on yet.

I have a sheet of cyanotype drying and I mixed up some ferric oxalate to print palladiums tomorrow... I'm so excited I'm bouncing off the walls!

 

[Mateo]

Padrisimo!
Did you make it yourself?

 

[Jeremy]

Yep, just finished it today.

 

[Mateo]

It looks like quite a few bulbs, how big can you print now?

 

[Jeremy]

My 16x20 contact frame slides in nicely, so up to 16x20

There are 12 24" bulbs in the box.

 

[mark]

Drool, drool, drool, slurp, drool.

I was just looking at the stuff to build one of these myself. Looked tough. Was it?

 

[Jeremy]

I only needed one band-aid
It wasn't difficult at all, the only problem was cutting the initial sheet of plywood down--it was too big to cut in the garage and it was raining outside for a straight week so it pushed my whole project back. I've printed up one cyanotype step-tablet while working towards some curves for diginegs. Seems to print quite quickly, taking only 4.5 minutes on a all-color black negative. I'm drying some paper to do a red colorized negative and a "pyro" colorized neg right now.

 

[Jeremy]

Hmm, I wonder if I'm going to have an issue with speed, I can cook a pyro digital neg (CMYK=54,33,100,13) in about 3 minutes. The strips look great, though!

My goal is to have my print up (palladium) in the challenge gallery by tomorrow night.

 

[kwmullet]

Very cool! Congrats!

I'll have to get you to walk me through the alt-process thing sometime. I'm strictly a silver gel guy.

 

[Jeremy]

Kevin,
Once I get my curves down I'll have you bring over a couple of images and we'll scan them in and make some palladium prints for you. One condition, though, you have to ignore the mess

 

[Jorge]

Congrats Jeremy....you are on your way bubba...

 

[sanking]

I am just wondering what you meant by this comment? The tubes should come on all at once. Is this not happening with your unit?

Sandy King

 

[Jeremy]

I've found with flourescent lights (in my experience with "normal" flourescent bulbs, I'm knew to Black Light bulbs) that they take a while to stabilize--they do all come on at once, my mistake on word choice.

I had it running for 2.5 hours straight and it stayed quite cool, I think it's a success!

 

[sanking]

I had it running for 2.5 hours straight and it stayed quite cool, I think it's a success!

Did you install a fan? If so you can run the unit indefinitely and it will not overheat.

Sandy King

 

[noseoil]

Nice box and well done. Looks like you could cook some prints with it if the times were a bit too long. Did you use any kind of diffusion glass to even out the light from the bulbs? Any signs of streaking because of the array of the tubes, or are prints coming out evenly?

 

[Jeremy]

Did you install a fan? If so you can run the unit indefinitely and it will not overheat.

Sandy King

I couldn't find a muffin-box fan locally that would work straight with 110V so I cut a hole and use a small deskfan. The deskfan butts right up into the hole and I could literally run the box all the time and it wouldn't overheat.

Sandy, I was just re-reading your UV source page on www.unblinkingeye.com and you wrote:

"This type of light source is reasonably fast, provides a large area of even illumination, is quite easy to operate, produces constant output almost immediately on being turned on (especially when using electronic ballast), and may be switched on and off with no delay. A fan should be used to cool the tubes because if they get hotter than about 105°F the light output decreases significantly. Fluorescent tubes do not require any appreciable warm-up time, and they may be restarted immediately."

Right now I just have it wired right into a plug. Does this mean that I can wire it through a switch and just turn the lights on after I put the contact frame in and then turn it off when the times up--or even better, hook it up to a GraLab timer?


Noseoil,
I've only been printing 1.5 x 5.5" step tablets to get my digital negative curves, but I plan on printing a large 11 x 17" to check for any hotspots. The inside of the box was spray painted white but from all of my research I won't have any problems with hotspots, but no reason not to check

 

[sanking]

Right now I just have it wired right into a plug. Does this mean that I can wire it through a switch and just turn the lights on after I put the contact frame in and then turn it off when the times up--or even better, hook it up to a GraLab timer?

Noseoil,
I've only been printing 1.5 x 5.5" step tablets to get my digital negative curves, but I plan on printing a large 11 x 17" to check for any hotspots. The inside of the box was spray painted white but from all of my research I won't have any problems with hotspots, but no reason not to check

You can indeed plug the light unit directly to a GraLab timer. I used my UV bank that way for a long time (now run it through a light integrator) and your exposures should be very consistent, so long as the bulbs don't get hot.

I would recommend positioning the unit so tht the tubes are about 4 inches from the printing plane. This will even out the light and eliminate any possible hot spots, without causing much of an increase in printing times over placement at 1-2 inches. The inverse square law does not apply to diffuse light sources of this type so for all practical purposes your exposure times will not vary very much between positioning at 1-2 inches and 4-6 inches. At more than 6 inches you would start to see some increase in exposure time.

Sandy King



Sandy King

 

[mark]

how did the BL bulbs do with palladium?

 

[Jeremy]

Thanks Sandy, I'll have to go pick up a Gralab timer then, here I come ebay! The box is built so that the bulbs are about 3.5-4" above the paper plane in the contact frame.

Mark, I'm hoping to print palladium today, but so far my cyanotype 13-step tablets look great. I am on my last step tablet for cyanotype now, but I need to let it oxidize before I can read it. I will start my palladium tablets next but I can speed up their drying and there's no oxidation so I should have a print today.

 

[Murray@uptowngallery]

I just dropped in - I didn't know what prep went into it...

Magnetic or electronic ballasts?

Is it uniform in illumination?

I considered a diffuser for a similar project with Super Actinic lamps. I don't know if you want UV component... acrylic, for example will block quite a bit of the UV. Not sure about white diffuser material, but referencing 98% UVF framing acrylic, it blocks wavelengths shorter than 400 nm. 'Ordinary' acrylic blocks alot, but the curve is so sloppy it's hard to state a percentage of at what wavelength it 'kicks in'. Roughly 70% blockage and I'd assume same wavelength. (Any) glass blocks below 380 nm.

Murray

 

[Jeremy]

It has electronic ballasts and it's quite uniform in illuminsation. I coated a 16x20 sheet of paper and couldn't find any varaitions in the density.

 

[Murray@uptowngallery]

Sounds great.

 

[Ed Sukach]

... 'Ordinary' acrylic blocks alot, but the curve is so sloppy it's hard to state a percentage of at what wavelength it 'kicks in'. Roughly 70% blockage and I'd assume same wavelength. (Any) glass blocks below 380 nm.
Murray

True about "ordinary" glass (~95% - 98%) ... but the composition of "ordinary" (non-coated) acrylics must have changed significantly since I've done spectrophotometry. The most UV I've ever seen attenuated through acrylics was about 5%.

 

[Murray@uptowngallery]

I got some literature from Atto-Haas and Cyro on their 'regular' and UF acrylic sheet. I don't remember who said what below...

1) The UV filtering component is blended into the polymer, not a coating.

2) They had no data (curves) for UV filtering of 'regular' acrylic because that's not one of the desired properties, but one guy (@ Cyro, if I remember right) said from his measurements it's about 70%, kind of a raggedy curve that creeps into the wavelengths shorter than 400 nm.

I think part of the question is what wavelengths are being discussed (narrow spectrum or broad band).

The context for the comparisons I was looking for were for picture framing. It seems most man-made UV sources have 'spikes' at a small number of specific wavelengths. The sun is probably broader (I'm assuming).

How the acrylic mfrs measure a broad range of wavelengths in the UV range is interesting...maybe there are 'tuneable' UV sources that can be swept across a range of wavelengths...???

I think the UV filtering specs for glazing materials boil the spectral plot down to %suppression between 265 and 380 nm for glass and 265-400 for acrylic, apparently all glass stopping wavelengths shorter than 260-ish (I don't know the exact number).

Regular plate glass is advertised (in PF industry) as having roughly 44% UVF. I found even that disappointing where one WANTS UV and needs to flatten materials under glass. I guess it's only a bit more than one stop so you just live with it.

There is UVT (UV transmitting) acrylic, but I dread to think what it costs, where one can get it, and doubt it's transparent to the visible wavelengths (can't see what's behind it)...maybe one doesn't care if you usually look behind alt-process prints.

Murray

 

[Murray@uptowngallery]

How has Jeremy Moore's platinum work gone with the blue box?

Murray