"Silkscreen UV Source" as Alt Process Printer

[Cletus]

I've been thinking a lot about getting set up for some pt/pd and other alt process contact printing. I have begun some research on various UV Source options, including a purpose-built DIY 'box'.

I did a Fleabay search to start and see what's out there and there seems to be a proliferation of graphic arts and silkscreen type sources. Someone even has one of (what kinda looks like) a silkscreen source here in the classifieds for sale as well. I could be mistaken about that, though.

I see that most of the screen printers have a glass 'platen', similar to a scanner, covering the bank of bulbs and most have a lid that seems to close flat over the platen/bank. Not much room for a contact frame.

Anyone have any comments about these type sources? Maybe even some experience with pt/pd printing using one of these? Are they capable of even illumination and reasonably short printing times?

It appears the horizontal, "lights-up" arrangement would require a little modification to suit for my purpose, but it seems feasible. Probably standard ballast and sockets allowing swapping tubes for something more optimized for alt process use?

There are a few proper UV Exposure units for sale here and there, but these screen printers can be got for about half what a purpose built photo source commands.

Thanks for your advice!

[Vaughn]

Take the glass off and turned the printer upside down (use something to keep the unit raised up so you can slide a contact printing frame under it. You will find that changing the distance from bulbs to contact printing frame will not change your exposure time much at all (the 'inverse square law' does not apply in this case).

If your contact printing frame can stand on edge, you can also stand the printer on end -- I actually do this with one of my light sources. Takes up less work space, too.

[Cletus]

Vaughn -

Great! That's what I was hoping to hear. Ryonet makes one of these which is basically an aluminum "apple box" sized thing - similar to the Edward's Engineering, only aluminum instead of wood - with 8 Black Light bulbs in the bottom and the glass plate covering the top. LFF user ndg has one of these for sale in the classifieds for $500, but I think it's a little too big for my darkroom. I'll be hunting for a similar, smaller unit I think.

Is this something like what you use? I was thinking maybe the printing frame could be placed negative side down on top of the glass plate, maybe mask off the unused areas of the glass? Either that, or turn the box upside-down and prop it up on some standoffs to leave room for the printing frame underneath? Seems like a pretty similar method to what's done with the purpose built boxes.

Last question: I was doing some reading on the "Unblinking Eye", a nice article by Sandy King, who seems to have done quite a bit of testing for alt process UV sources. I noticed the bulbs in the screenprinting box are spaced fairly far apart, compared to Sandy's recommendation they should be only something like 0.5" apart for single tube fixtures. Are you getting consistently even development using the screenprinting box, where it appears the bulds are spaced much further apart?

Thank you for your input on this! I still have quite a bit of reading to do before I spring for the expensive B&S pt/pd Kit and other necessary stuff, but I think the UV source should come first - the most essential - purchase on the road to alt process printing. I am assuming the same source, if it works with pt/pd, would be acceptable for Kallitype, Vandyke and similar processes?

[Jan Pietrzak]

Cletus,

In my early days of pt/pd printing sun lamps were available and cheap. The next source is to build you own and I have done that about 15 to 20 of them I think. But thats no the issue. The screen box on the forum will work just fine. Just put the negative down, then the coated paper and close the lid. The top/lid will need some foam for pressure. This is the way the old Aristo Pt printer worked no contact print frame. And that is the way most screen printers work.

Ok on to the spacing of UV tube. Yes the closer the spaceing of the tubes the more light you can get in a small space, the faster the printing, to a point.

The other sources are plate burners and big wearhouse lighting units (mercury vapor) lamps will work also, but to much light spill for me.

So I have left you with a number of sources the think about, Oh the one I use, a friend gave me an Aristo unit. When I teach workshops I use a series of 3ft 12 tube boxes and contact print frames.

Jan Pietrzak

Ps Freestyle sells a re-designed screen unit for Alt printing and the Edwards units

[Cletus]

Jan / Vaughn -

Thank you, I really appreciate your advice and the details on what's worked for you. I've done quite a bit of reading already and have a pretty good idea what this will take, but there's no substitute for hearing what's worked well from someone who's done this and has some (or a lot) of experience.

I think I can find my way from here and I should be able to find a screen printing source for a good price with a little patience.

I'll try to post some prints here once I get set up, probably a couple months....

[Vaughn]

For platinum printing I use a variety of light sources -- an Edwards Engineering light source (their 'kit' -- which I do not recommend), another homemade version of the EE light source, two 175W merc vapor lamps side-by-side (security lamps bought at the hardware store -- this I use vertically) and 750W merc vapor lamps (self-ballasted). Jan is right about spill-over light, but that's no problem if you have the space to have the light in a different room.

If you are handy wit htools and basic wiring, making your own is easy and much cheaper.

Bulb-spacing -- as already mentioned, not a problem with even lighting, just speed of printing.

I found that the bank of BL tubes to work fine for platinum, but gave a softer carbon print (sharpness and contrast) -- I use the merc vapor lamps for carbon printing.

Have fun and look forward to seeing your results!!

Vaughn

[Steve Smith]

The only possible problem I can think of is that as screen emulsions are exposed through graphic film which is either clear or opaque black (no greys) the evenness of light is not so important as it would be for a full tonal range negative.


Steve.