Large Format Photography Forum > LF Forums > Darkroom: Film, Processing & Printing > frustrated exposing prints in sunlight...grrr!
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I got all set up to do some pt/pd this morning, full- bright sun clear sky low humidity. In other words perfect. But then I bring a sheet out and that perfect sun was gone. Clouds seemingly from nowhere came in and I was sunk...again. I need to acquire/ build a printer. I have found plans online for a printer you can make with 8 18" t12 fluorescent tubes using black lights tubes, but I have not been able to source the materials cost effectively. What I am wondering, is what do you guys use. Is it best to go ahead and bite the bullet and get a printer from B&S or is there an updated plan using maybe a four-light fixture. Any input would be greatly appreciated. In the meantime I will scour the DIY forum etc. Thanks, and have great days.
Those are BLB tubes (and fixtures). They have a filter built in to block most of the visible light and let just the UV through. BL tubes are a little cheaper (they do not have the filter) and actually seem a little faster. If you make a system from scratch, they are what one usually gets.
BL tubes are faster than BLB.
Try "The Bulbman" for tubes. Even easier is the use of CFL-UV bulbs. The total cost of building a unit is reduced and made simpler since no ballasts need to be installed. These are also available from the Bulbman and similar sources. If you are printing 4x5, one CFL is sufficient. For 8x10 negatives, one will suffice also if moved a little further away from the printing frame, but most of my students have used four bulbs.
A few months ago I finished a very basic UV exposure box for under $200 total. It uses a 6 bulb 32w T8 fixture. The fixture is 48 inches by 20 inches, and I can do up to 2 16x20 prints at one time. Estimating initial height of 7 to 8 inches, to even out the light. The bulbs are separated by about 2 inches.
Unless you live in parts of the southwest where the sun is reliable source of UV light it is best to invest in a good UV printer for alternative printing, especially pt/pd where the materials cost are so great.
Another good type of printer for alternative work is the platemaker type units of NuArc 261k, 261ks, Amergraph UL28, UlF-28, etc. These units use powerful HID lamps and usually come with built in vacuum and light integrator. You might be able to find a used unit on Ebay or Craigslist.
If you want to built a unit with a bank of BL tubes just do a search on built screenprinting light. There are many youtube videos on how to make your own.
I used this http://www.reptilesupply.com/product.php?products_id=2184 for my Platinum printing demontration workshop. Exposure time about 10 min at 2-3 ft for an 8x10 neg . You can go to local PetSmart to get one. UVA & UVB needed for this kind of printing.
Sandy, What would your thoughts be on this unit?
I'm not Sandy but you don't need anything that costs $400. For my gum and Vandyke printing I built a simple plywood box open on the two long sides and installed normal "under the counter" florescent lights - I think a bank of 8. Cost maybe $50-$75 and I'm not at all handy so if I could do it anyone can.
I used a similar unit for printing pt/pd recently at a workshop. Exposure times for pure palladium were pretty fast, about 8-10 minutes as I recall, and the unit is relatively light and portable.
For some general considerations of UV light sources for alternative printing see my article http://unblinkingeye.com/Articles/Light/light.html The article was put up more than ten years ago but most of the information is still current.
That is really interesting. I have never thought of reptile supply stores as a source for UV source. This should be very helpful to those needing a printing unit.
Two potential problems with these lights. One, they put out a lot of heat, and two, it takes them a couple of minutes to reach full radiation after turn on. So for really accurate exposures you need to turn on the bulb and allow it to warm up for a couple of minutes before beginning your exposure.
Indeed Jim, it's cheap, EZ set up , get the job done. Tropical and salt water fish store also carry these UV light bulbs too.
Great information. there are lots of options. I think I am going to go with the T12/BL option and make a printer along the line of the Edwards printer, but less elaborate. Sandy, thanks especially for your exhaustive article. It really made decision making process easier. I will keep you posted as I get into the process. thanks again.
Brian- did you mount a fan on your box?
Bruce, I currently use one that is almost identical for kallitype and carbon transfer printing. I am quite happy with it compared to my plate burner as I don't have to worry about it melting carbon tissue. Exposures are quite a bit longer, mind you.