Using 8x10 contact printer with 20W screw-in BL fluorescent bulbs.

Discussion in 'Alternative Processes' started by Jacek Luc, Sep 12, 2005.

  1. Jacek Luc

    Jacek Luc Member

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    Hi all. I wonder if any of you are using a Rexo 8x10 Master Contact Printer model 3 mfg. by Burke & James for alternative processing.
    After reading an article by Sandy King, I would like to try Kallitypes.
    My printer has 7+1 screw-in round light bulbs. Three in the centre row, two on the right and two on the left (+ one off centre, very dark, which I do not know what the use is).
    I was thinking to change them for screw-in 20W Blacklight Fluorescent bulbs. The space between top of bulb and glass is about 6" (16cm). On the beginning I would use it mainly for 4x5 printing.
    This contact printer does not have any fan for cooling. I wonder if I would have to add one.
    I would like to get your opinion on whether or not this could work.
    Thanks Jacek
     
  2. Donald Qualls

    Donald Qualls Member

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    The off-center bulb is for a safelight bulb, used in setting up with silver gelatin contact printing papers to ensure the negative, any mask, and paper are all correctly aligned on the glass. Probably unnecessary with platinum and other UV sensitive processes, since you can set up in subdued room light.

    Incandescent BL bulbs will print, but likely no faster than unfiltered bulbs would (think multi-day exposures); the coating merely subtracts the visible light so you can see the effects of the tiny fraction of the light emitted by the tungsten filament in the near UV. You'd most likely get much, much faster printing if you can locate compact fluorescent bulbs with a "daylight", "grow-light" or similar broad spectrum coating, or even CF BL bulbs (I've never seen such, but can't decide why they haven't appeared, given there's a market for the very, very weak incandescent BL bulbs). Even ordinary kitchen type CF bulbs will probably print faster (and run cooler, and use less energy, and last longer) than incandescent BL.
     
  3. Donald Miller

    Donald Miller Member

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    Since you did say fluorescent BL I will assume that you mean the bulb that Sandy King and others have used for exposing Azo. I would assume that from what I have heard about that particular bulb that this may work for you. I personally have not used that bulb but I have used the F15T8BLB lamp and it works fine.

    The BLB incandescents are an entirely different matter...I have used those and they will not expose Azo and hence would be even worse on alt process.

    Regarding your question about a fan, I can not answer your question other then to say that for an equivalent wattage the fluorescent lamps are usually much cooler. If you decide to try the lamps that you mention, I would just wait until I tried it before I decided on a fan.
     
  4. sanking

    sanking Member

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    Donald,

    He is not talking about using incandescent BL bulbs but coiled fluorescent tubes that screw into incandescent fixtures. Watt for watt they put out the same amount of UV radiation as regular tubes.

    Sandy
     
  5. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    Sandy- do you have a source for those bulbs? I haven't seen them at Home Depot or Lowes.
     
  6. sanking

    sanking Member

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  7. Donald Qualls

    Donald Qualls Member

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    Oops, guess I need to read more carefully. I'd never seen or heard of a CF version of a BL fluorescent (as I said above) until this thread -- I'll bookmark those sources, since I can see those as the easy way to make a UV printer (no ballasts to buy, just install sockets in the correct pattern and set up a cooling fan). Of course, $72 for just the bulbs makes me shudder a bit (not even counting the sockets and the box to mount it all, and then the contact frame on top), but still a lot cheaper than buying ballasts and doesn't require me to become an instant expert in wiring fluorescents...
     
  8. Allen Friday

    Allen Friday Member

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    I am in the proceess of building a UV light source using BLB tubes. I was a little hesitant to go with the build from scratch method, simply because I don't like wiring--even though I have done some in the past. In Sandy's excellent article on UV light sources, he describes using prewired fluorescent light strips for building a unit. I followed up on that idea and started pricing units at Home Depot.

    I found Commecial Electric Shop Lights with instant on electric ballast which fit my needs. Each shop light is ready to plug into the wall out of the box. When I got one home, I took the metal plate off the top to examine the insides. Everything is pre-wired. The only problem with the prebuilt unit is that the lights are too far apart. My solution, take the bi-pins, wiring and ballasts out of the pre-built unit and put them into a wooden frame to size. To do so requires removing six sheet metal screws. I get the advantage of having the bulbes closer together, and I don't have to do any wiring.

    I rechecked at Home Depot to see about the cost of buying the parts individually and assembling them. Guess what, it is cheaper to buy the pre-wired unit than to build from scratch. I purchased the 48" unit form Commercial Electric. I don't know if they make a 24" unit. It would be worth looking into if you want to use 24" tubes.
     
  9. Jacek Luc

    Jacek Luc Member

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    Thanks for the reply.
    The bulbs I am talking about are listed on the website www.starmgc.com/theatre.html
    Name of the company is Star Light & Magic. The reference for that bulb is F60U. It is a 20 W UV Fluorescent Blacklight. Screws into a standard socket. Cost 16.95$.
    Donald what do you think would be the correct pattern for setting the bulbs? And how much space between them.
    Jacek
     
  10. sanking

    sanking Member

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    Allen,

    My 48" UV bank is made of the two-tube fixtures. When I originally built the unit I found that the spacing was not ideal if you just placed the fixtures side by side. That left the outside tubes on adjacent fixtures much closer together than the two tubes in the fixture itself. I simply adjusted the unit by narrowing the distance betwen the tubes in each fixture. This involved nothing more than drilling a hole in the end of the fixtures for the new anchor position. It may sound complicated but in fact it was very easy and took very little time.

    Sandy
     
  11. Allen Friday

    Allen Friday Member

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    Dear Sandy,

    Thank you for your reply. I picked that up from your article on UV printing lights. It didn't seem overly complicated to reposition the fixtures.

    Personally, I am a much better wood worker than I am electrician. I mentioned my approach to taking the unit apart for those who might be reluctant to build a light unit because of the wiring involved. The shop light plugs directly into the outlet, so the only wiring involved is to attach the ground to the metal reflecting plate. By taking the units apart, I saved the extra weight of the metal units.

    The fact that it is cheaper was a bonus.

    I bought the 48" unit because I am building a 48" unit. They would work equally well in a 24" unit, one would just have more wire curled in the top of the unit. If Commercial Electric makes a 24" unit, then that would be the way to go.

    Also, I want to thank you for the excellent article on UV light sources. I searched my books and the net for different articles. I found yours extremely helpful in guiding me on which type of light to build for my needs.
     
  12. waynecrider

    waynecrider Member

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    Did you ever try the bulb you were talking about? I have been looking at the H400BL, and the prices are really good at the sight you mention, but I wonder about the abilites of the bulb.
     
  13. juan

    juan Subscriber

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    I made a UV printer using 4 of the 15-watt versions of this bulb. Works fine for 8x10. I found my bulbs at the local outlet for lightbulbdepot.com

    juan
     
  14. waynecrider

    waynecrider Member

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    Juan, 15 watt versions of the coiled flourescent bulb?
     
  15. kudzma

    kudzma Member

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    I built a UV box with 12 20W spiral fluorescent BLB bulbs from Save on Lighting (see Sandy's link). My box has 12 bulbs (3x4) spaced 6" apart (from center of bulb) and 5" above the contact frame glass. It gives perfectly even lighting, easily covering 8x20" (my biggest format). Print times are nearly identical to a similar box with 8 F20T12/BL bulbs, which had a slight light falloff at the edges of 8x20. This was the reason for the rebuild. The screw in BLB bulbs are great! Bright, start instantly and warm up fast.

    Linas
     
  16. juan

    juan Subscriber

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    Sorry, yes, 15-watt versions of the coiled flourescent tube. I'm noticing a little fall off on the ends of my 8x10, so I'm thinking of getting two more - making a bank of 2 x 3 bulbs. I just screwed the bulbs into standard porcelain light fixtures from the hardware store - that spaces them about 2 1/2" apart. The tips of the bulbs are about 2" above the negative.
    juan