UV vacuum box for pt/pd

TheFlyingCamera said:

Those look fine. Just as a point of clarification, if you're doing pt/pd, whether from in-camera originals or enlarged (digitally or traditionally) images, you'll need a NEGATIVE, not a positive. Actually, the 6x17 size/proportion isn't that problematic for contact printing frames, if you have the right frame. I have a vintage (1920s/30s) 12x20 contact printing frame that would be just fine for making prints of that proportion, and I also have a similar vintage 14x17 frame in which I could do two at a time. But vacuum frames are nice, if you can find one you can afford and have space for it.

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coigach said:

I'm wanting to have a bash at pt/pd printing, and although I plan on using a digitally enlarged positives from my original film, I hope my question still stands and is within APUG's scope...

I use both 6x7 and 6x17 panoramic medium format cameras. Because of the wonky size of the 6x17, contact frames are likely to be problematic, so I'm looking at a UV vacuum unit instead. (I use a big vacuum unit at the Print Studio for my polymer photogravures, and have come to appreciate the advantages of vacuum units).

Do you think something like this would be a good option?
http://www.exposureunits.co.uk/UV-Exposure-Units-With-Vacuum.html

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Davec101 said:

You might want to test out the unit before buying, when i started looking at these types of a units quite a while back i experienced problems due to the fact that the uv tubes were set at a fixed distance and could not be modified resulting in uneven expsoure and what seemed to look like some sort of 'uv burn' on the final print. there might be a way around this but like I said see if you can test one that would be best.

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coigach said:

Thanks for this, very useful info. Do you remember which models you tested?

It's unlikely that I'll be able to test equipment - I live north of Inverness in the highlands of Scotland, so things are a bit trickier...!

Any advice on other approaches or options to consider? (Budget is a consideration, the vacuum box links I posted are my price range).

Is there an ideal distance for the tubes?

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Davec101 said:

On that link you posted i tried the model at the bottom which is beige in colour.

Ideal distance with my own set up, shown below is approx 9 inches, bulbs 1 3/4 inches apart.

View attachment 59436

On a budget others options are to create a uv exposure unit yourself with uv tubes in a wooden enclosure, instead of using a vacuum use a heavy sheet of glass, will work upto 11x14 inches any larger you really need a vacuum unit to maintain sharpness across the print.

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TheFlyingCamera said:

I'm talking both. If he enlarges from 6x17cm to whatever size he wants to make his final prints, a 14x17 inch contact frame would handle two prints at a time, or a 12x20 inch frame would handle an even larger single print.

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coigach said:

Thanks again for info. Will now investigate the possibility of a homemade unit (well actually a made-for-me by a friend who is a joiner to trade!).

Another question though, possibly very stupid, so be gentle .

I lustfully looked the picture of your setup, looks fabulous.
(there was a url link here which no longer exists)
But if the bulbs are at the top facing down onto the paper, how does your vacuum work??
(I use a huge UV box at the Print Studio for polymer photogravures which has vacuum on top on a hinged lid, and bulbs below. The plates are placed face down facing the UV bulbs, and the top lid closed, then the vacuum seal is used to hold plate flush to glass).

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platebreaker said:

I just skimmed this post but why cant you use the light source that you do your polymer plates one? Thats what I would do.

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