Screen printing UV light box for Alt. processes

[oldglass]

Hi,

I was looking at ebay and I saw some people sell what they call Screen Printing Exposure Unit or Light Table. For example this one: 140353250255 (that's ebay's item id, just copy and paste to ebay's search).

From the description and picture, that is basically a box with 8 UV 15 watts unfiltered tubes.

Anyone used one of these for alt. process printing? it seems to be slightly more economical (and well made) compared to those dedicated UV light boxes for alt. process.

 

[Jim Noel]

It will work,but the tubes seem to be spaced rather far apart and no cooling fan is obvious. For this kind of money you can buy a new unit designed for the purpose from Bostick and Sullivan.

 

[oldglass]

From Bostik and Sullivan:

11x14 dimension, price is $639

From ebay:

20"x24" with buy it now for $349

That's quite a bit of difference in price if you ask me

 

[Ann M]

The UV eposure unit looks as if it could be pretty useful. I've used a much larger one at the printmakers' workshop I belong to for exposing photo-litho plates and silkscreens. The only thing I would wonder about is how accurate the timer on it might be, as the one on ours is pretty basic. But that may not matter? In any case, you should be able to switch it on and off with a darkroom timer. (That's what I'm planning to do with the facial solarium that I'm going to use for exposing cyanotypes.)
Would you need a cooling fan? How long are exposures likely to be? On the print worshop's large unit, it only took 1 min.-1 1/2 mins to expose a plate or a screen but I don't know what its rating is. (I reckon ours would be too powerful to give any accuracy for alternative process exposure - exposing litho plates etc. may be have much more tolerance in exposure times.)
I hope this has helped - if only to give you ideas for more questions to ask. A printmakers' workshop may be able to give you some advice, maybe even let you try exposing something if they have a similar unit. Good luck!

 

[Davec101]

Hi,

I was looking at ebay and I saw some people sell what they call Screen Printing Exposure Unit or Light Table. For example this one: 140353250255 (that's ebay's item id, just copy and paste to ebay's search).

From the description and picture, that is basically a box with 8 UV 15 watts unfiltered tubes.

Anyone used one of these for alt. process printing? it seems to be slightly more economical (and well made) compared to those dedicated UV light boxes for alt. process.

I have not used one of these however you could build your own like many alt process people do as it would work out cheaper and is not very difficult to build. The size of the ebay one has 20x24 coverage, if you intend to print that large I would recommend a vacuum frame despite what the advert says on ebay! Also building your own you can dictate the distance between the UV lamps and the contact printing frame/vacuum frame which you cant with the one on ebay, this is an important factor in getting a good exposure.

 

[oldglass]

Nah, the largest print that I see making is about 11x14, so the Exposure unit is actually quite a bit larger than what I need/want.

Oh well, I'll keep looking for an alternative then.

 

[rmann]

I build one using 5 Home Depot black light 18" fixtures - as I remember they where about $16 each including a black light bulb - I put them in a plywood box and used a power strip to plug them into. Its been working just fine for me - exposure times are in the 3 to 5 minute range. I use a Gralab timer on the power strip - you could add a fan if you want to the box and plug it in the power strip also. As I had most of the stuff around the house I think it cost about $150 total for the set up.

 

[Steve Smith]

It may not be even enough for alt. process exposure. It doesn't matter so much for screen print emulsion as it either gets fully exposed or not exposed at all. A screen emulsion is either clear (fully washed out) or solid and this corrosponds to black or clear areas of the positive film used to create it. There are no shades of grey involved.

Because of this, it is common to over-expose a screen emulsion just to make sure.


Steve.

 

[An Le-qun]

I recently got a scrounged Kepro 200e UV exposure frame (normally used for printing circuit boards?) for <$60. Works magnificently.

 

[oldglass]

Anyone used this?

http://www.chauvetlighting.com/led-shadow.html

For those who can't open links during work, it's a UV LED bank for Club/DJ purpose.

 

[Loris Medici]

Interesting LED unit. OTOH, specifications say 405nm, not "real" UV. (By definition UV starts at 400nm and goes below...) Something in-between 350-370nm is what you're looking for!

To parrot Dave & rmann, you can do one yourself (or have it done for you, by a handy friend...) pretty cheaply and easily! Mine - with 16x24" coverage - costed me something around USD 135, including the plywood structure (mimicking the B&S design exacly - w/o legs though...), high output electronic ballasts and 40W bulbs ect...

Regards,
Loris.

 

[Mainecoonmaniac]

I've never used an UV LED light box before. But here's an idea on how to make one.

http://www.instructables.com/id/UV-LED-Exposure-Box/

 

[2F/2F]

I have used a commercial screen printing exposure unit for many cyanotype and van dyke prints, before I had my own contact printing frame, and I still use it for very large (over 20x24 inch) prints (class projects). The unit has a vacuum pump and a pliable rubber cover to hold the sandwich tightly together. The exposure is adjustable in "units" – A.K.A. seconds. Not enough? Give it multiple blasts. They work fine. I lay down a sheet of diffusion material on the glass of the unit, then the glass, then the neg/s and/or objects, then the coated paper, emulsion side down, then a piece of plywood with rounded edges.

Mind, you this is a commercial unit; it is large. It is about four feet deep, three feet wide, and five feet long. You have to go up a few steps to get a good working angle from the top. It may produce more exposure per second than one of these home hobbyist units.

 

[oldglass]

Interesting LED unit. OTOH, specifications say 405nm, not "real" UV. (By definition UV starts at 400nm and goes below...) Something in-between 350-370nm is what you're looking for!

To parrot Dave & rmann, you can do one yourself (or have it done for you, by a handy friend...) pretty cheaply and easily! Mine - with 16x24" coverage - costed me something around USD 135, including the plywood structure (mimicking the B&S design exacly - w/o legs though...), high output electronic ballasts and 40W bulbs ect...

Regards,
Loris.

Thanks, Loris, that's probably my answer, a fact that I overlooked about the wavelength of the output light. Still, it's tempting to try if at 405nm, it still could trigger chemical reaction for alt. process.

I know that the most sensible and economical answer is to build it yourself, but I'm still looking for easier answers. Plus, with half-finished DIY projects at hand, I need another one like I need a poke in the eye.

 

[Ben Altman]

A light integrator to control exposure is nice too; the output of tubes changes radically from cold to warm, so timing exposure is not always accurate.

 

[nsurit]

I got plans for a UV light box from a list member, built it and have been very satisfied with the results. The file is too large to attach here, however if you will send me an email, I'd be happy to share it with you. Bill Barber

 

[alexhill]

I've never used one of these for alt photography, but I have used them for silk screens. I think there would be a difference noticeable in the prints similar to printing in the shade or in direct sunlight. This style of exposure box uses a single wicked bright bulb at the bottom of the unit, about 3 feet away from the surface.