Resin filters and hot lights

Anyone ever try putting a resin filter (like Cokin) over a hot light?

I'm using high intensity LED lights for video. I'm considering trying to mount a square resin color correction filter permanently directly over the LED array.

A check with my remote thermometer shows the surface of the array gets up to 150 F (perhaps less--I don't know if those things are thrown off by high intensity light)--I would be mounting the filter about half an inch from the surface of the array. I expect that long-term exposure to high intensity light will eventually bleach the filter (would have to check periodically for that), but I'm also wondering at what temperature a resin filter will melt or deform in the first place.

I didn't find any info through Google...wondered if anyone had tried putting one over some other kind of hot light.

Resin camera filters (and eye/sun glasses) often use CR39 optical resin. This is a thermoplastic (of course) and can, according to the current blurb, be used "continuously at up to 100°C and up to 1 hour at 130°C". (ie 212°F and 266°F respectively) Other than quoting unsubstantiated figures from an unnamed source (aka the ever-unreliable, questionable value Wikipedia), I can't help. According to these figures, you should be OK temperature-wise (with the customary caveat, of course) but the main problem I see lies in the bleaching. Particularly if you're planning on using anything at the blue end of the spectrum as these are long recognised as among the most fugitive of colours.

"Suck it and see" seems to be the answer to the question, unhelpful though that probably is. Fortunately, Cokins are hardly expensive so if you destroy one or two of those it's not going to break the bank. An alternative - backed by copious amounts of published data available - may lie in the Lee range of HT filters (Rosco will probably also make a range). Lee themselves say "HT products have been specifically developed to give additional resistance to extremely high lamp temperatures, and should be ordered using the HT prefix". Note though, the Lee HT range is rather limited compared with their full range of colours. It all depends on what you want to do.
http://www.leefilters.​com …lour-list.html#&filter=ht

The story behind CR39, as used by Cokin, can be found at http://www.ppg.com …aterials/Pages/​CR-39.aspx although it's a historical document and not concerned with the physical properties per se.

why not just get a color correcting gel sheet? they are six and a half dollars for 20"x24" at BH and made to sit in front of tungsten fresnel lenses.

http://www.bhphotovide​o.com …els/ci/24442/N/​3945526706

whatever you choose to do, i'm guessing it would be a good idea to leave some space between the front of the light and gel/filter so that the light can radiate heat off the front and not over heat itself.

Whortleberry wrote in post #17615680
Resin camera filters (and eye/sun glasses) often use CR39 optical resin. This is a thermoplastic (of course) and can, according to the current blurb, be used "continuously at up to 100°C and up to 1 hour at 130°C". (ie 212°F and 266°F respectively) Other than quoting unsubstantiated figures from an unnamed source (aka the ever-unreliable, questionable value Wikipedia), I can't help. According to these figures, you should be OK temperature-wise (with the customary caveat, of course) but the main problem I see lies in the bleaching. Particularly if you're planning on using anything at the blue end of the spectrum as these are long recognised as among the most fugitive of colours.

"Suck it and see" seems to be the answer to the question, unhelpful though that probably is. Fortunately, Cokins are hardly expensive so if you destroy one or two of those it's not going to break the bank. An alternative - backed by copious amounts of published data available - may lie in the Lee range of HT filters (Rosco will probably also make a range). Lee themselves say "HT products have been specifically developed to give additional resistance to extremely high lamp temperatures, and should be ordered using the HT prefix". Note though, the Lee HT range is rather limited compared with their full range of colours. It all depends on what you want to do.
http://www.leefilters.​com …lour-list.html#&filter=ht

The story behind CR39, as used by Cokin, can be found at http://www.ppg.com …aterials/Pages/​CR-39.aspx although it's a historical document and not concerned with the physical properties per se.

The LED array is a patch about 1.3 inches square. It comes with a glass diffuser that clips over it. But the glass diffuser clips would also hold a 67mm filter adapter ring, so my thought is to clip a Lee resin filter adapter into it. That would naturally place the resin filter about half an inch or so ahead of the LED array surface with open convection channels top and bottom. I wouldn't use the diffuser dome at all because I'll always be using an umbrella or other modifier.

I'd mainly use it for CTO to balance with tungsten "practical" lights when necessary and color correction (a light magenta). If this arrangement works, it would be much less fussy than gels.