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

You've linked to two different sizes of gel shield (both of which I suspect are too small for you).
Note also that in order for any gel shield or heat shield to work, there must be airspace between the shield and the color.
Gel is cheap (especially with an offer gratis). I'd try it first before investigating all the other possibilities.

Oops. Thanks, Derek. How do you create the airspace gap? Is there some material that I can use as a spacer?
 
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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.
@Kelite or @GreyWyvern can you explain the difference

Dichroic glass will be Very expensive. I seriously doubt you will have that many issues. I have 65 light fixtures with 750 watt bulbs in them at work. The gel in them is a light pastel color and we change it every 6 months as it slowly fades. If you were trying to use a really dark color, then it would be likely to fade after 10-20 hours of use. But having gel actually melt due to heat is quite unusual especially when using a lighter color like the one in the pictures.
 
What's your budget for this and are you set on using those exact fixtures? I'm thinking it might be easier and cheaper to use some used modern lights that are designed to hold gel. I did a quick search for "L&E Broad cyc" and found used lights that will act very similar to your light, starting at $30 each for used ones.
 
I would steer clear from putting gel directly on the glass, I recall doing something similar- playing with a worklight and gel, and winding up with crispy gel baked onto the light... anyway you have to figure most theatrical lights have a gel frame holder that is several inches away from the lamp and glass lens, and even then gel will ripple and eventually burn through. Rather than try to fabricate some kind of gel holder, seems like it would be pretty easy to cut a sheet of gel to fit the outer face of the cube, it wouldn't be pretty but you could just tape it on.

Really though, if you're worried about a fire hazard, the issue isn't the color media, it's the 500w lamp that is creating that heat. I would seriously consider switching to an LED fixture, there are a ton of options that may be better than a conversion.
 
Great thread guys, keep the ideas coming!

The main difference between heat shield and Gel Shield is pretty substantial. Heat shield is simply clear, thin polyester which provides another layer to collect heat. Gel Shield, on the other hand, is an 8 mil thick clear substrate that has a vacuum deposited dielectric coating on one side (similar to dichroic glass). This substrate, while clear, is as thick as an Apollo steel gobo and more rigid than polyester heat shield. The dielectric coating applied to Gel Shield reflects both IR and UV energy, reducing the harmful rays which ultimately cause organic dyes to migrate from the center of the gel. When you see a lighter area in the center of a gel cut, the dye has actually moved toward the edge of the gel, away from the most intense heat. Gel Shield negates the migration, allowing up to 7x the life of even the darkest gel transmission.

When building color scrollers we add a layer of Gel Shield to the fixture side of the device, allowing Apollo gel strings to last an unbelievably long time.

So, there ya go- Gel Shield 101 class completed! :D
 
That one is a 10" x 10" piece for the old Smart Color®.
That one is a 11.75" x 11.75" piece for the Smart Color® PRO 10.

Not sure why the pictures aren't showing. They are precut with mounting holes for the unit they go on. They could be cut to the size you need. Speaking of which, what size is the fixture?
An easy-ish way to have an air gap between the gel and Gel Shield is to get two gel frames that are the same size and have holes in the corners. If you can't find them with holes, stack them and drill holes. Attach them together with standoffs between. Then you just need to figure out how to attach that to the fixture. Take care to be sure that the Gel Shield isn't touching the glass.

You'll notice the sticker that says "This side towards lamp". That is important to pay attention to. The Gel Shield has a coating on one side. That is what makes it do what it does. Without that, it is just a piece of plastic. The coating filters out IR coming from the source, which is what does damage leading to degradation of gel. There is around a 20% transmission loss.
IMG_20190301_083002919.jpg

EDIT: ...and what @Kelite said!

Oh, something else I meant to mention. If you are unsure of which side should face the lamp, say the sticker went missing, take a DMM and set it to take an ohm reading. The coated side will give a reading, while the uncoated side will not. The coated side goes towards the source.
 
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Great thread guys, keep the ideas coming!

The main difference between heat shield and Gel Shield is pretty substantial. Heat shield is simply clear, thin polyester which provides another layer to collect heat. Gel Shield, on the other hand, is an 8 mil thick clear substrate that has a vacuum deposited dielectric coating on one side (similar to dichroic glass). This substrate, while clear, is as thick as an Apollo steel gobo and more rigid than polyester heat shield. The dielectric coating applied to Gel Shield reflects both IR and UV energy, reducing the harmful rays which ultimately cause organic dyes to migrate from the center of the gel. When you see a lighter area in the center of a gel cut, the dye has actually moved toward the edge of the gel, away from the most intense heat. Gel Shield negates the migration, allowing up to 7x the life of even the darkest gel transmission.

When building color scrollers we add a layer of Gel Shield to the fixture side of the device, allowing Apollo gel strings to last an unbelievably long time.

So, there ya go- Gel Shield 101 class completed! :D
This is an excellent, educational and informative post that OUGHT to be in the Control Booth Forum's WIKI, if it isn't already.
@dvsDave
Toodleoo!
Ron Hebbard
 
Yeah, it's really just the fire hazard that I need to eliminate, while maintaining the original look and effect as much as possible. It would only catch on fire if the delay relay failed and allowed the light to stay on, rather than shutting off after 10 seconds. The colored plexi gets warm after that 10-second run time, but not hot. Then it has an hour to cool down.

I wish that I could switch to LEDs, but the retrofit LEDs for these halogens just aren't bright enough. Only one comes close, and it doesn't fit the casing. So the only way would be to swap out the fixture. That would be hard. First, it would mean changing the look of the piece. Second, the light is in a laminated box that's part of the art (see first pic) Thirdly, two of the three sculptures are attached to the electronics casing with a metal bolt. (In my first pics, I showed you guys the original sculpture, which has a wood box--it's probably my father's prototype.)

Here's the orange.
 
I'd like to spend $100-$150. I'll be replacing the formica on the display boxes, which may cost a couple hundred since the colors aren't common and I'll probably have to order full sheets.

I'm going to look into dichroic glass and devon glass from Gray, but if I can't match the colors or it costs a fortune, I think gels and the Apollo gel shield over tempered glass will suffice. My one question there is how to create that gap without altering the look of the art piece. But with all of your ideas, I feel really close to the solution. I dissassembled the green so you guys can see how the original plexi is in there.

 
Honestly, a 10 second on time has me almost completely not worried about changing a thing. However, I do understand your concern.

I’m trying to approach this from an art conservation mindset. As such, LED is completely out of the question as that would completely alter the look and feel of the work.

Gel is certainly going to be the lowest cost option and probably allow for the closest color match. Perhaps heat shield on the side of the glass near the lamp and gel on the other would work? You’d have to experiement.

Dichroic, while it would last forever, is also visually too different from the original work.

Part of me would want to rebuild using proper theatrical fixtures, but then one would have to worry about white light leak.

The more I think about it, perhaps making a front “window pane” to the display box is better than mounting the color media directly in the floodlight. Just moving it a few inches like that should greatly increase its lifespan.
 
Maybe the other way to look at this is: If the timers are a potential point of failure, replace them with some kind of computer control, a little arduino or something. That way the aesthetics stay the same, but it gets a bit safer. Of course, that is a whole 'nother rabbit hole, but it is a thought.
 
I'm leaving in a few hours for a weekend trip, but I didn't want to step away without thanking all of you again. This is a fascinating introduction to a whole world of materials that I never knew existed. I had this project tabled for months because I didn't have a fix, and here you all have offered multiple solutions that would all work. I'm so grateful for your knowledge.

My next step is going to one of these theater supply shops near me to check out swatch books. As I'm out of town this weekend, it'll have to wait until next week. I'm hoping that looking in person will narrow the field.

The more I think about it, perhaps making a front “window pane” to the display box is better than mounting the color media directly in the floodlight. Just moving it a few inches like that should greatly increase its lifespan.

This is a promising idea. The depth of the display box would definitely accommodate a window-pane type construction. I'll bring it up with my father. Ideally, I'd like to fit the tempered glass, gel and Gel Shield in the existing frame that holds the plexi, so as not to change the original. But the frame is only a half inch deep, so that may not prove ideal. Then again, the 10-second on-time might make a tight-ish assembly more forgiving? @GreyWyvern The assembly instructions you provided are great--thank you! Forgive my ignorance, but could you link to a standoff? I get some kind of medical gel when I google it :)

Maybe the other way to look at this is: If the timers are a potential point of failure, replace them with some kind of computer control, a little arduino or something. That way the aesthetics stay the same, but it gets a bit safer. Of course, that is a whole 'nother rabbit hole, but it is a thought.
Would an arduino have a fail-safe that the old timers don't? This also leads back around to installing a thermal shut-off, which is a different avenue but would be effective. The worrier in me wants the plexi out, but I go back and forth on whether I'm being overly cautious.

I'll be back Sunday night. Thank you all again!!
 
Hey Grey: We doan need no steeken standoffs, we haz nutz.
I think this may have been before you discovered us.
 

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