HiAny theatre / disco lighting experts out there ?One of my new stained glass products is a lamp, with a wooden base,and the 'shade' shaped like a 'Toblerone' bar standing on end.Inside the shade is a compact fluorescent lamp (let's not have thatdiscussion again ! ) - and the shade consists of various pieces ofstained glass, fused glass, polished agate slabs etc...The CF lamp is used because the finished lamp is not all that large,and a conventional tungsten lamp would give out too much heat.Only problem is - wih certain types of stained / art glass, it'ssometimes possible to see the outline of the lamp bulb, or of theplastic body of the CF lamp - which detracts a little from the overalleffect.So - bright idea time How about using a piece of rolled up translucent material between theCF lamp and the 'shade' - just to soften the outline of the bulb alittle....I vaguely remember, from my college days running theatre / discolighting, that we had (?)acetate sheets called 'gels', that were usedin front of flood / spot lights. I see that these are still available- I'm guessing that a 'neutral density' one is the way to go...Alternatively, I see this item wonder whether this would do the trick. Never seen it before -has anybody used it and can tell me if it is as rigid as 'real' gel ?Looks like it might just be 'fabric' - in which case it wouldn't stayput inside the lamp.Alternatively - does anybody have a suggestion for areadily-available, durable, safe material that I could use instead ?Many thanks in advanceAdrian

Adrian,As I recall (and it was a long time ago) the neutral density gel was to allow the effective brightness to be reduced without using a dimmer (and the consequent colour shifts of running lamps at different filament temperatures) or any form of aperture control.In a vaguely similar way, ND filters can be used photographically to allow a larger aperture/longer exposure to be used when required. It certainly does not act as a diffuser in this role!The linked product looks to be appropriate (but I don't have the experience to judge - just 'makes sense' level).

Lighting gel / filter / diffuser ?

Feb 21, 2008 21 Replies

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Its a diffuser but as you mention at an output cost

Gel isn`t particularly expensive, but bnot sure if the OP is considering this for a one off or is seeking something to use in a production item. Even production quantities get a lot of sleeves out of a sheet.

There is holographic and prismatic optical diffuser films made by companies like 3M, generally used for things like display backlights, these are expensive.

Gel is a self extigushing polycarbonate commonly used in front of 2kW lamps, would rate it as safe even in direct contact with an 11W CFL. Stapled it around linear fluro tubes for years.

Even ultra clear glass is around 95% transmission, would think woven nylon cloth would be significantly below this. Spun diffuser is usually glass fibre of some form, think 2kW is probably a small light on a TV or film set. Silks and frosts tend to be plastic films.

Sleeve would be preferable, trapping heat around CFL ballast bases isn`t good for them.

Adam

Somewhere in-between I'd expect to sell maybe 20 of these lamps in a year - so it's sort of 'production' quantities.

The lamps themselves are about 12" tall and each side of the lamp is

4" (it's 'Toblerone'-shaped). So I'd imagine (cba to do the maths on a Saturday afternoon ) that one sheet of 12" x 12" gel would sit quite comfortable inside the 'shade' of the lamp - and be held in place by its own 'springyness' - this would also allow it to be as far away as possible from the CFL bulb.

As each finished lamp is a one-off 'art' item, I think that the cost of a sheet of gel can be 'absorbed' in the final selling price - assuming that it's less than a fiver or so...

As mentioned above - I like the idea of a gel / film as it would tend to be self-supporting.

OK - just waiting on my local (Dublin!) distributor to get back to me

- maybe I'll have to call them on Monday

Thanks Adrian

Lighting gel / filter / diffuser ?

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