Lighting gel / filter / diffuser ?

Question

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

Rod · Accepted Answer

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).

Adrian · Answer

HI RodThanks for the reply..Ah - probably not one of those then No - I suppose it wouldn't ......You're in the same boat as me then...perhaps there's an expert about ?ThanksAdrian

John · Answer

When I did stage lighting you could get various degrees of "Frost" gels

Peter Parry · Answer

Use an acrylic tube of diameter suitable to fit over the lamp and leave a bit of room for air circulation and cut to length so it covers the bulb completely.

eg

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upon quantities you intend to make either buy translucent rather than clear tube or make it translucent by getting a cylinder hone such as

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running it up and down inside the tube until you get the desired effect (Cylinder hones are flexible devices used on a normal electric drill which have 3 abrasive pads designed to prepare the surfaces of things like engine or brake cylinders -they produce a fine series of scratches which if used in plastic tubes gives it a translucent surface a bit like rubbing it with sandpaper).

Adam Aglionby · Answer

Diffusion gels are available in quite a range, spun isn`t probably what your looking for it softens the glare from big light sources at a distance.Frost is a slightly smaller sledgehammer for same purpose.

To reverse the linear look , a Silk is possibly what you want, this, clear, gel is brushed in one direction so might mitigate the vertical linearity with a tube of horizontal orientated silk. In extreme cases silk horizontal and vertical but lose a fair amount of light.

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in yellow pages for local theatrical lighting trade counter, they`ll stock one or both of the above 2 ranges, have flick through their swatch books, gel isnt expensive.

HTH Adam

Adam Aglionby · Answer

Addendumusenet  and  could do withthe traffic if you have similar questions :-)

Thomas Prufer · Answer

Fiberglass, as used in auto body repairs? Comes in woven and non-woven(felt-like, mat, I forget the term...), it's heat resistant, and could be firmedup with epoxy. too...Thomas Prufer

Adrian · Answer

HI PeterThanks for the replyThat's a possibility.Seems a bit 'overkill' though - and possibly tricky to transport in 2mlengths (we live in the back of beyond out here in South-westIreland).I was thinking that sheet gel might work out cheaper on the postage...It's a possibility though - thanksAdrian

Adrian · Answer

HI AdamThanks for the replywhat results...Thanks againAdrian

Adrian · Answer

HI ThomasA possibility - but maybe a bit 'user-unfriendly' (if it's the stuffI'm thinking of it sheds fibres rather easily)I was hoping for something that I could just slip into position,if you know what I mean !ThanksAdrian

gilli · Answer

Hi, I would go to  where you should get goodadvice.  They should have all the diffusers and gels you need...the diffuserscome in different types   and densities...degrees of light reduction...or you could get clearin different densities...   They are made to withstand very high heat so you could put them asclose to the bulb as you like    just staple into a tube as a test and drop it over...they handleboth rosco and lee.   I suppose you could glue into a tube shape for more permanent job.   They will give you a sample book of both makers so you canexperiment and choose.   I have some on hand which I would post if you like...not sure howmuch or which ones...don't use them    anymore. You might have to buy a whole roll if you want thediffuser....best to check first...the gels    they will do in smaller sheets, but, from memory, the diffusersonly come in rolls...ring to check first.  David G

Lighting gel / filter / diffuser ?

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