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How to keep your gels from burning out too quickly

Discussion in 'Lighting and Electrics' started by dvsDave, Feb 20, 2003.

  1. dvsDave

    dvsDave Benevolent Dictator Administrator Senior Team CB Mods Fight Leukemia

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    Don't you just hate it when your gels get that horrible hole in the middle of them? I know I hate it!! But I recently became aware of a neat product that helps tremendously with this vexing, and expensive, problem. There are gels that are designed to reflect the IR radiation to avoid heating up the gel too much.

    Get them from Rosco;

    Get them from Apollo;

    Get them from Lee;
     
  2. delnor

    delnor Active Member

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    Have u tried the Appolo ones? I have never used them. Lee and Rosco are big in this area. They are great. I personaly am a Lee fan.
     
  3. dvsDave

    dvsDave Benevolent Dictator Administrator Senior Team CB Mods Fight Leukemia

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    Honestly....

    Honestly... I have never used them before :lol: I haven't gotten any of them yet!! But I will tell you about how they perform when I do get some!
     
  4. dwsobel

    dwsobel Member

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    One quick fix I have heard of is poking holes in the gel itself, to let some of the heat dissapate. ~David
     
  5. Mattech

    Mattech Member

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    We just installed a similar product, or maybe its the same product, a "heat shield". Its installed in between the lamp and the gell, in a seperate gell frame. Is that what your talking about??? We had a gigantic problem with the gells in our dark blue washes burning out. And we have tried everything and are hopeing this will work.
     
  6. dvsDave

    dvsDave Benevolent Dictator Administrator Senior Team CB Mods Fight Leukemia

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    yeah, that's what the post was about...
     
  7. cruiser

    cruiser Active Member

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    heavy lee gels burn out very very quickly when using pc's and par cans, and I have found that poking small holes, like you would when cooking a cake, either out of the beam area or right in the centre helps cool down the gel and they don't burn out anywhere near as quickly!!

    good cost effective way of avoiding the problem!
     
  8. digitaltec

    digitaltec Active Member

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    What I do to keep my gels from burning is take a small needle and poke several holes all throught the gel. Also, the max intesety you should ever need to use on a show is 75-85. Thats your max. If you go over that then you will burn gels and are probably blinding whomever is on stage. Just my 2 cents.
     
  9. cruiser

    cruiser Active Member

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    Never heard of running a show only at 75-85. If i need 100 I use 100, if I need 20 i use 20....
    Ive found Rosco Supergels seem to burn out extremly fast also, Rosco E-Colour and Lee seem to last the longest...
     
  10. jrlang

    jrlang Member

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    try useing lee HT gels. There is not much of a selection, but they do with stand heat longer then any other gel on the market.
     
  11. seanb

    seanb Member

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    madness! When I'm lighting music shows, I want the backlight/toplight to be fairly bright to give me the definition I need. When I'm using dark colours, I will need to have two fixtures at 100% My front lights are usually at 60-70, depending on the song and area, but that's with a light colour and soft frost.
     
  12. DVkid

    DVkid Member

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    GAM also makes a product of this sort by the name of "Heat Shield 99." They sent out 8.5"x11" sample sheets whent hey launched the product but I never used it.

    Anyways, find it at www.gamonline.com.

    -DVkid
     
  13. ship

    ship Senior Team Emeritus Premium Member

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    Don't forget that if you poke a bunch of holes in your gel you are letting that much more white light thru the gel. At that point, what if you went one step lighter in gel color than did not need to poke a hole in your gel because the saturation is not as much, than of course I'm also in the boat that either I'm using heat sink if it's saturated or those fixtures are not on a 100% long if ever which tends to keep down the heat. Don't forget the before mentioned bench focus or focal point as in if you find on a par can your gel is burning up, perhaps you can put the gel into a top hat or gel extender to get it away from the focal point. On heat shield, the more distance you space it from the gel itself, the better it's going to work. Also keep your gel away from oils such as fog goo, it coats the gel and retains the heat. On that 3.5Q6 Leko I was working on Friday with the 750w Color Command lamp in it we tried some 1/4 CT boost and 1/2 color temp boost. The 1/2 CT burned a hole in itself immediately. Not that the fixture needed it, it already had a higher color temperature than you could get out of a S-4 Leko, but should I need to color correct at full, I would either use the 1/4 CT blue or add a double gel frame with 1/2" spacers between frames so I could have both heat sink and gel away from the lens.
    To point, I have found that when you poke a hole in a lamp hot enough to be melting the gel, that hole makes a really good place to start melting from. Been there done that, at least for me it did not work. Good gel is also another factor. Some gels you just can't use on fixtures without heat shield first.
     
  14. Inaki2

    Inaki2 Active Member

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    Yup I totally agree with you on the grade of the gels. I remember once I was helping out on a show back at my school and some of the guys doing it bought acetates to colour lights, well, some started melting and dripping in the stage...yuck!!!!
    If you're using high temp fixtures, most gel companies have a High Temperature series on most colours.
     
  15. digitaltec

    digitaltec Active Member

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    Use dichroics :)
     
  16. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    As Ship pointed out, focal length plays an important part and this is why I do not own any 'stubby' Par cans. The lamp is just too close to the gel. Have had to hire them in for some shows but only used them in a chase and only at about 75% intensity.

    Poking holes in gel is a band-aid solution and not one that I would recommend.

    I have used the HT Lee Gel with good effect on my QI fixtures (500W halogen flood in which the Gel is very close to the lamp). However, as pointed out previously, there is not a great range of colours available. I use the QI’s predominately for architectural lighting and can usually get away with the colours that they have, or can get by with standard Gel and dim appropriately.

    As for the maximum dimmer setting, I must admit that I tend not to take the master above the 80% mark and then rarely have the individual channels at 100% (possible for the dark blues etc). In my honest opinion, I find that there is very little noticeable difference in having the master at full or at 80%. However, keep in mind that I am doing shows where my lights are very close to the action.

    For example, I did a show on the weekend in which I had to light up a building for a party. At the beginning of the night I had the lights balanced out on the individual channels (between 60% and 80% to achieve a uniform wash) and as time passed and the sky got darker, I gradually reduced the master fade. When I checked it at the end of the night, it was close to 50%. This is something that not only reduced the heat transfer to the gel, but actually kept the same intensity of light on the building, as there is less competition between the lights and the ambient lighting from the sky. Another added bonus was that the guests didn’t get blinded from the light, which can be a problem when you turn the lights up to battle the ambient light until the sky darkens. This is one of the things that I see done quite often. People flood a building or garden with light early in the evening, as they want to get set up before the guests arrive. However, very few then dim the lights as the sky darkens and end up with a very bright party, which lacks atmosphere.

    Whilst this may not be all that relevant for theatre, it is just my little tip for anyone doing outdoors work and will also help extend the life of your Gel.

    Cheers,
     
  17. ship

    ship Senior Team Emeritus Premium Member

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    Yep, I do the same on lowering intensity and having about 80% as peak even when matching lamp wattage to desired output. That way also you have the threshold to cross when you need a bit more light. OK, perhaps it was more 90% in most cases, but still, 90% intensity is much less heat on the gels than 100%.

    From that, up until I got into lights that were 1,000 Watts or more, I never had problems with gel burning out, or at least non-overly saturated gel over a long period of time. It lightinging from a high intensity more than burning up still. That's why I would be concerned about a Leko say that burns thru it's gel. Check your bench focus before you scratch your head, than if it's still burning up, is it the rated lamp for the fixture or one over that? Given the abstraction from the designed position of gel to light focus, light extenders or shields might be required.

    In my case however I did come into a situation of head scratching at one point. Had some 6-cell cyc units that were left on a good amount of time at I expect full and they would within minutes burn thru it's gel. More than that they smoked up a storm at 1,000 Watts per channel. I eventually figured out someone cleaned the cyc unit reflectors with something that left a residue on it, and that residue which burned off taking the reflector with it also deposited itself on the gel as a type of oil causing it to retain heat. This was what was melting both gel and spaced heat shield installed in front of it. Replace the reflectors and it was only a question of 1,000w lamps at the center of the fixture not having proper ventilation out of the fixture when the gel was at the top of the fixture in having it bun up towards the center of the fixture first since the center of the fixture would be hottest.

    To correct this problem, believe me, I tried all methods. In the end, it was only a question of either lowering the wattage, or lowering the saturation given full wattage if you could not live with even a heat shielded few minutes of extended life as it ended up being.

    Should you have problems with gel melting and lowering the dimmer setting, lowering the transmission does not work or will not work for your situation, I would recommend either going with a lower wattage higher color temperature lamp or adding an extended heat shield even fan as needed to cool the gel.

    By the way on architectural installs, dichroic or glass filters are longer lasting and also an option for higher output.
     
  18. miniwyo

    miniwyo Member

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    In my experience I have heard my things about gels and I have found out that poking holes in them doesnt really do anything but let out white light. We tested this 2 parcans with a brand new blue gel in each. one with holes one without we ran thm as worklights so they were basically on all day 6 days a week and they burnt out equally as fast.


    RJ
    Rock Springs Wy.
     
  19. Inaki2

    Inaki2 Active Member

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    Great answer, yes, when it comes to heat and colour rendering dichroics are great but still, they're fragile, not so good at tours and oh yeah...expensive!!!
    Still, for a fixed theatre with a nice budget, dichroics is great
     
  20. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Thanks miniwyo – I can now reference your experiment as scientific proof to support my earlier statement on this practice.

    In addition to Ship’s last post, I can concur that I have only had issues with Gel burning out in the 500W QI lights and this is due primarily to the fact that the gel is only a couple of inches from the lamp. I have had some custom frames made to fit my QI’s which increase this distance by a couple of inches and also provides airflow without causing much bleed. I also removed the glass plate, which decreases the heat buildup by promoting airflow around the lamp. Since doing this I have not had a Gel physically burn and by this I am talking about melting. However, they will certainly not last as long as they would in say a 300W Par 56.

    I guess we need to differentiate between physical damage to the Gel and loss of colour due to heat. Gel will always deteriorate with age and this will be exacerbated by several factors, which have already been covered. However, as Ship has pointed out, if you have Gels that are melting or becoming crispy, you may need to look at the fixtures and application, as I did with my QI lights.

    Very true Ship – unfortunately my work is show by show so this is not a viable option for me.
     

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