'pouncing' gel

[Beans45601]

I have seen pouncing gel talked about, but I have never really seen anyone talk about why they think it does not work. I have only seen people describe why they think it works, or people simply say it does not work. My thoughts are this, please give me your ideas.

When you poke a hole in something, what you are really doing is creating a slit and then pushing all the material to the outside of the of the needle. You are not actually punching out any material, like you would with a dermal punch. Because of this, you are actually creating a small hole and around that hole, you have simply displaced material that was supposed to be in that hole. Poke a hole in some gel, close your eyes and feel around for it, you are certain to find it. When you are talking about gel, that extra material equals a slightly ticker spot, or, a darker spot. These dark spots adsorb more light and end up getting hotter than all the gel around it. In pouncing gel, are we actually just creating hundreds of points of failure, that were not there before?

People usually say that these holes help some of the heat escape from between the gel and the lens. Unless you went way, way over board, I can't imagine ever being able to poke enough holes to get any sort of airflow to remove that hot air. Also, in general, our instruments are pointed down, maybe instead we should be drilling holes in our lenses so that the heat can travel up and away from the gel.

What I'm wondering is: is pouncing gel actually doing far more harm than help?

 

[chausman]

(keep in mind this is a freshmen in high school talking)

Airflow isn't needed for heat transfer. Just a way to let heat escape. I would think that the increase in thickness around a hole is so minuscule, it doesn't hurt or weaken the gel.

Imagine you have your R02 special center stage, and it is the only instrument onstage. When you stand off to the side of it, you don't feel very much heat, but when you stand in the special, you can feel it. There is heat there, even though you aren't standing above the source. And, the rear of the instruments are designed to handle the heat. Why would we want to weaken them structurally and cause undo light spill?

It can't be doing too much harm if it is (somewhat) effective, and hasn't caused any terrible side effects.

 

[Van]

It's always been my assumtion that the pouncing of gel worked sort of like the anealing of glass or steel. The gel has certain internal stresses. Those stresses are exacerbated by the introduction of heat. The process of pouncing does not , necessarily, relieve the amount of heat, but rather breaks the "stress lines" in side the material.

 

[josh88]

Even assuming that somehow drilling holes in lenses could create a benefit rather than more problems there are already heat sinks and designs to funnel heat out the back of instruments, but part of directing that much light forward just goes hand in hand with putting a ton of heat forward no matter what anybody does behind the lens to try to abate it.

Picture what Van said but with water (different I know, but bear with me) if you filled up a container with water and had one weak side (say the side with gel) eventually the pressure of the water would exert enough force to burst through the gel and create a hole (burn out) but if you punched the gel making a bunch of little holes you allow the water to trickle out as it fills, never allowing for the catastrophic failure, or if you're filling faster than it is draining you've at least significantly delayed the failure.

That's the theory at least. Honestly I don't really buy it, I think the benefit it might provide doesn't add much in the long run and it really seems to be a drop in the bucket, there's so much heat coming through that it doesn't change much. For the same reason I don't think it speeds it up as you mentioned because the material is still there, I don't think it would collect enough extra heat to change the outcome. However some people swear it works and extends the life of gel. But so do heat shields or color extenders, or any number of other things. I've never looked but I don't suppose anybody has ever done a real study of whether it has an effect or not so it's always anecdotal evidence.

/personal opinion

 

[gafftaper]

I always was told it was for releasing heat. I agree that the amount of heat released would be pointless compared to how much heat is generated. I have never done any scientific testing but it's been my experience that it didn't do much. So I tried it a while and then gave up.

Hey Kelite! It would be interesting to hear some thoughts from your gel wizards at Apollo about if it's at all useful or not.

 

[MrsFooter]

Pouncing gel was practiced by my predecessors for exactly the reason others have mentioned: that it releases heat and gel lasted longer. Seeing as I have a rep rig full of 1K Strand Centuries that get VERY hot, (just ask the burn scars on my left wrist,) burning through gel is actually an issue for me. However, since the beginning, I was suspicious of the reality of pouncing gel's effectiveness. It seemed like all it did was give the burnouts a place to start.

So I did a little experiment. I cut all brand new gel for one of my systems, and pounced half of it. Half went stage right, half went stage left. The gel that was pounced definitely melted through faster. Don't get me wrong, the un-pounced gel burned, too. But it was more likely to lose its pigment and crinkle than totally melt. That was enough for me to disband the practice.

 

[Beans45601]

Seeing as I have a rep rig full of 1K Strand Centuries that get VERY hot, (just ask the burn scars on my left wrist,) burning through gel is actually an issue for me.

My entire rig is 1k Strand zooms and 1k and 2k Strand Fresnels. What I wouldn't do for more of those 8" fresnels.... But yes, I have many similar scars.

You didn't happen to notice where the gel melted through first, did you?

The lens hole suggestion was a joke y'all!

I don't agree that this build up of gel aroudn a hole makes enough of a difference. In a 2k Fresnel, adding any more material is huge, I would imagine.

Chausman- what you are talking about is radiant heat, the holes in the gel supposidly would be helping take care of hot hair trapped between the front lens and gel.

 

[derekleffew]

...Hey Kelite! It would be interesting to hear some thoughts from your gel wizards at Apollo about if it's at all useful or not.

From the wiki entry pounce wheel, in response to a question as to whether Apollo's PerfGel lasts longer due to its perforations:

...The 'pouncing' of gel has been a practice used by many theater technicians over the years, often to the point of achieving a 'voodoo, black magic' result. The perfing of Apollo PerfGel does not weaken the material, but predisposes a specific tear route. I can't honestly say it aids in the cooling of the product without running the risk of selling snake oil.

Not believing my lighting professor in 1980 when he discredited the practice, eventually I tried it for myself, on Roscolene and Cinemoid. As with most things, he turned out to be correct.

...I've never had any luck with "pouncing" gel in deep colors, to me it just gives the color media a place to start to burn quicker.

Another unbiased opinion:

...We just did a show with a bunch of dark colors, and we did the pounce wheel trick. You can't tell that we pounced the gels, but guess what... It didn't buy us much, maybe one extra performance before replacing, but that isn't that much of a savings over a long run.

In short: It's a myth, a myth.
Yeth?

 

[gafftapegreenia]

I think perforating any Roscolux made through their extrusion method would be problematic as punctures would likely allow the sandwiched color dye a place to escape.

Anyone ever use diffusion and a deep saturation gel in the same light and notice how the gel color bleeds onto the diffusion?

 

[TEarlywine]

I think perforating any Roscolux made through their extrusion method would be problematic as punctures would likely allow the sandwiched color dye a place to escape.

Anyone ever use diffusion and a deep saturation gel in the same light and notice how the gel color bleeds onto the diffusion?

Yes, often

 

[shiben]

It's always been my assumtion that the pouncing of gel worked sort of like the anealing of glass or steel. The gel has certain internal stresses. Those stresses are exacerbated by the introduction of heat. The process of pouncing does not , necessarily, relieve the amount of heat, but rather breaks the "stress lines" in side the material.

Basically the plastic gel would relieve stress in the opposite manner of metal? Thats actually a fairly interesting thought... Ill have to ask some buddies in MatSci about it.

 

[zmb]

I think silk gels might have some sort of internal forces, it always sets into odd creases while burning out. But would the pounce wheel provide more stoppage points to keep deformation to a minimum?

 

[shiben]

I think silk gels might have some sort of internal forces, it always sets into odd creases while burning out. But would the pounce wheel provide more stoppage points to keep deformation to a minimum?

I kind of doubt that gel has tons of internal stress until it begins to shrink under the influence of heat. The crease marks would be an uneven distortion as a result of having different polymers (or actual silk strands) mixed together. Pouncing will not help relieve forces in gel, since it shrinks, rather than expands, weakening the structure would undoubtedly cause more problem from a materials perspective than not doing so. If gel was behaving like a metal and expanding, having joints to absorb the expansion a la the skin of the SR-71 might be beneficial. However, holes would not really help this at all, actually they would weaken the material. In situation where the material is shrinking, lowering the holding power of the polymer sheet really wont do you any good on any polymer piece, gel included.

 

[ship]

I have a probably some form of tarred duck fabric star rotator screen that in theory is about c.1911. Couldn’t imagine hand punching the phonograph like grooves in it but circular coincentric holes specifically in it, (though for the age and labor practices - possible it might have been by hand punched.) Just wondering if possible that this pounce wheel with perhaps a couple of the holes punched modified for larger stars came from a pounce wheel in concept and say a 1Kw lamp not melting it for some heat to escape? I would not think the fabric or coating on it fire proof, yet it seems to have only warn out the thread attaching the fabric to the outer steel rim in not catching on fire with single lens 1Kw lamps an flammable materials in front on the wheel. This as opposed a similar in age mica wheel with flames painted on it also found.


For some historic sense of where the myth came from, perhaps it is the above punching holes in a coated wheel for stars to get out, this a start of such a belief or just that color media was way different back than and say yes the gel of old days could benefit from a pounce wheel.

Otherwise... yea, tried it on dark modern gel for 1K cycs’ and it didn’t work and even I think starts the melt down faster.

Checked Fuch's 1929 on the subject, a mentin on page 408-15 on a mention of Color media. "The drying out and cracking of gelatin sheets" (real gel/glucose sheets) "can often be retarded somewhat by lightly rubbing into their surface, before they are first used, (this is literallally thin colored "Jello" like product used for stage lighting) a thinfilm of either some vegetable oil or glycerine. If small cracks occur in a gelatin sheet, or if a small portion of it has faded badly, a "wet patch" can be made by...." (Wouldn't you like to know such info obscure...)

Gotta buy the book and I literally had a c.1956 version in my hands I gave away (put on his desk) this past weekend in not needing. This giving I have the UK and US 1929 versions on hand already as well as a few other books my former Mentour owned that I was offered.

Townsend gelatin color media was what Fuch's Stage Lighting (the bible for early lighting) recommended in 1929. Charles Townsend, 276, Pearl Street, New York. "This firm is perhaps the oldest in its field. Its assortment of colored gelatin sheets is a very extensive one. ....

No mention of a pounce wheel in looking. Some other technologies in use at the time, but no concept of in say 1929, the pounce wheel in use for the chapter on colored media that I saw.

Specifically, no mention at least in 1929 of a pounce wheel in usefulness, but perhaps a start for it's invention.

 

[gafftaper]

From the wiki entry pounce wheel, in response to a question as to whether Apollo's PerfGel lasts longer due to its perforations

I thought these quotes might confuse some people so I want to clarify that Apollo PerfGel is perforated in order to allow easy tearing of gel into predetermined sizes. It is not perforated in order to prolong the life of the gel. No dealing with scissors or big cutting boards. Just tear along the dotted line into perfect squares.