Conventional Fixtures Gels for Art Piece with a 500-Watt Halogen

Discussion in 'Lighting and Electrics' started by LeeMiro, Feb 27, 2019.

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  1. LeeMiro

    LeeMiro Member

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    I am restoring a light sculpture from the 70s and hoping you all might supply me with some basics on gels. Short version: Can you recommend a line of gels that I can safely use with a 500-watt halogen bulb? The long version has background on the sculpture and the safety issue . . .

    The sculpture is one of my father's from his early artist career. It is a flood light retrofitted with green plexi in place of the usual tempered glass. It has two timers that sync up randomly, plus a delay relay that turns off the light after 10 seconds. The effect is the room is briefly flooded with intense green light at random intervals.

    The original has a safety issue. Although the light turns off after 10 seconds, a failure of the electronics could result in the light staying on indefinitely and causing a fire. (It's a 500-watt halogen pointed at plexiglass.)

    These lights haven't been run in years, and I want to bring them back into commission. My plan is to rip out the flammable plexi and replace with a theater gel placed over tempered glass. Does this sound reasonable? Should I be looking for gels with higher heat resistance? I see that Lee's High Temp Filters are rated to 220 C.

    I don't have a way to measure the heat produced by the halogen bulb, but it's currently 1.75 inches from the plexi cover.
    Photos of the piece below for reference. Pardon the appearance--it's been sitting in a garage for decades.

     
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  2. Amiers

    Amiers Renting to Corporate One Fixture at a Time.

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    If you put the gel on the outside just replace it when it starts to lose it’s color.

    500w at 10 seconds won’t hurt it. Even if it stays on all day until you notice the guts not working.
     
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  3. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    The fixture originally came with a clear glass cover. I use to use them a lot in small storefront theatres in Chicago in the 1980s. It was an outdoor floodlight that could be bought at Crafty Beaver (don't laugh, that was/is its real name) for $9.99-14.99. I used binder clips to attach the color media.

    You didn't say if the exact color of green is important. Guessing from the pictures, and off the top of my head, I'd say you want a Roscolux 93. If the exact color is important, you'll want to get a swatchbook from your local theatrical supply dealer to choose the color.

    I'm pretty sure LeeHT has been permanently discontinued due to production problems. Regular Roscolux should hold up just fine. The glass will block most of the thermal heat and some of the infrared energy. Make sure the glass supplier knows the application; regular tempered glass may not be sufficient.

    Good luck. Let us know how it turns out.

    One more thought:
    Home Centers still sell the same basic fixture, except updated to use an LED source. Perhaps better to change the entire fixture, and save yourself the energy and heating/cooling costs. With a white LED source, choosing the gel becomes even more tricky, but not insurmountable. Check your Lowe's/Home Depot/Menard's/Tractor Supply/Rural King/Ace Hardware.
     
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  4. RonHebbard

    RonHebbard Well-Known Member Premium Member

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  5. techieman33

    techieman33 Well-Known Member

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    The Lee High temp has been discontinued, but there probably still a lot of it floating around in inventory all over the place. If you go with gel I wouldn't put it directly on the glass. Anything you can do to keep it even a 1/2" off the glass will prolong it's life by quite a bit. You could always get rid of the halogen light and stick a couple of green led lights in there. You should be able to fit a couple of these in that box. My fear is that it won't give you the same effect. The LEDs will be instant on and off. With a halogen there will be a brief period while the light comes fully on, and then a couple of seconds of glow after it's turned off as the filament cools back down.
     
  6. Jay Ashworth

    Jay Ashworth Well-Known Member

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    I was going to recommend a glass striplight roundel... right up until I saw the pictures.
     
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  7. Michael K

    Michael K Active Member

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    Indeed, but regular green tinted plate glass would be an option, assuming it doesn't have an issue with the high heat.
     
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  8. LeeMiro

    LeeMiro Member

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    You guys are awesome!! Thank you so much. I stepped out thinking it would be a while before I got a reply and came back to all of your ideas. I'm thrilled that this is going to work.

    I would indeed prefer to match the color as closely as possible. I have two additional lights--one orange, one blue, so I will look into a swatch book so I can match all three. I hadn't heard of Lexan--if it can withstand Tommy, than surely it can withstand this halogen :) Will any polycarbonate do, or are only certain types heat-resistant?

    I considered replacing the halogen bulb with an LED, but the only one I found that was anywhere close to the equivalent lumen output won't fit in the original fixture. The brightness is important to the piece--the 500-watt halogen really does flood the room with light. Also, swapping the plexi for a gel seems easier than replacing the fixture.

    Noted on being sure that I get the correct type of tempered glass. That's really helpful. What type of material would be appropriate to float a gel over the glass?

    I'm going to go see about finding a local theater supply dealer :)
     
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  9. JAC

    JAC Active Member

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  10. jonliles

    jonliles Well-Known Member Fight Leukemia

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    Also, Apollo makes a heatshield that can be used between the lamp and the gel that will extend the life of the gel. Dichroics would last forever (until broken).
     
  11. bosox242

    bosox242 Member

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    Not sure what part of CT you're from, but in Central CT two local places are Show Lighting Corp. in Berlin, CT and Advanced Lighting & Sound Solutions in Manchester, CT.
     
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  12. techieman33

    techieman33 Well-Known Member

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    I think it depends on how long it's going to run. A piece of dichroic glass that big would cost at least $100. So if it's going to run once a week for a couple hours then it's probably not worth it. But if it's going to sit somewhere and run 24/7 for years then the glass might be worth the expense.
     
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  13. JD

    JD Well-Known Member

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    There is another alternative that would allow the fixture to stay exactly like it is but make it safe. Simply install a thermal fuse or thermal cutout in the fixture. If it were to stay on, the fuse or cutoff would shut it down when it started getting hot.
    If it is only meant to be on for a few seconds, then you could used something pretty low in temperature, Maybe 100c. Thermal fuses are pretty cheap, you could pick up several in the 80 to 120 degree range and see if it works with the lowest.
     
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  14. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    OP is in Hartford. Perhaps you have some roughly 6"x12" "scraps" of R93, R23, R68, and/or a Lux swatchbook, you could "lend" for the good of advancing art.
     
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  15. LeeMiro

    LeeMiro Member

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    I've just plugged in the lamp to see how often it goes off so I give you all specs on the total amount of time it's on in a day. A permanent material is ideal, but I could always save extra gels if I need to replace it down the road.

    Dichroic glass is another material that's new to me. You say that the glass reflects the heat back to the lamp. . .Would this would significantly increase the heat in the enclosure (which is made from particle board and laminate, and ergo flammable) Or would the fixture casing absorb most of that heat?

    Thanks, JD. This was my father's thought--just add a thermal shut-off. It would totally work. I think my cautious nature prefers removing the hazard entirely, but it's definitely on the table, especially if I have trouble matching the original colors.

    That sounds great. Would that let me get away with mounting the gel directly on tempered glass?

    I'm in the Hartford area, so both of those stores are definitely do-able. Thanks!

    I will report back this evening with the frequency of the lamp turning on. That should help figure out gel vs. dichroic glass or Lexan. Really, the most important things to me are 1) preventing a fire in the event of an electronics failure 2) matching the color to maintain the original as much as possible.
     
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  16. bosox242

    bosox242 Member

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    I have R23, R68 and/or a Lux swatchbook I could give. @LeeMiro, let me know if you're interested.
     
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  17. microstar

    microstar Well-Known Member

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    fxlight.com makes a selection of heat-resistant color media products including Fade-not X gel. They say they can match to any gel color. Interesting website.


    Screen Shot 2019-02-28 at 5.23.03 PM.png
     
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  18. LeeMiro

    LeeMiro Member

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    I've had the light sculpture plugged in for a while now. The light turns on for 10 seconds every hour, so a total of 4 minutes daily, or about 24 hours of on-time in a year. [Edited to add: I figure I will leave it plugged in.]

    I still don't know what temperature my 500-watt halogen would reach if it didn't shut off, but looking online, it's probably about 570 F. Another source says as high as 1,200 F. As it's a 1970s halogen, it's hard to know.

    With this in mind, do you guys have guesses on how long would a gel last?

    Thanks for the link @microstar ! I'm checking it out now.

    @bosox242 Thank you for the offer! I may take you up on that. My first stop will probably be to the shops you mentioned in Berlin and Manchester to see what they carry.
     
    Last edited: Feb 28, 2019
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  19. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    The Gel is pretty unlikely to melt if you put it on the outside, but colors will fade over time. I would go with a layer of Apollo Heat Shield (which is clear and protects the color gel) and then a layer of the color you want. Send a private message to @Kelite (from Apollo) he will help you find a local Apollo dealer. If you are lucky he'll send you a gel book too. Remember with Gel that you can use two layers to make your own colors. I would take a gel book, tear it apart, and hold different combinations of gel in front of a light until you find just the right color you want. Don't try to judge based on what gel itself looks like, you need to see what it looks like with light going through it.
     
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  20. LeeMiro

    LeeMiro Member

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    [
    Great, thanks! That's super helpful to know about layering gels. I'm going to take a look at the dirchroic glass, devon glass and this FX Fade-not, too, but a gel might be simplest. Is this the Apollo Heat Shield? I also see the Smart Color Pro 10. Not sure what the difference is.
     
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