'Dazzle-Free Photoflash Photography' - Infrared-Transmitting Coating for Flash Bulbs

[holmburgers]

This article was written by R.B. Morris & D.A. Spencer and appeared in the British Journal of Photography, 1940, Vol. 87, p.288-289.

I'm assuming that it's public domain at this point and it is reproduced here as a scan of a print from a micro-film reel obtained from the Spencer Art & Architecture Library at the University of Kansas.

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In the article are given 3 formulae.

1) an Infra Red Filter Coating for Photoflash Bulbs
2) an Anti-Dazzle coating for photoflash bulbs used in conjunction with [panchromatic film]
3) a Formula for converting "Cellophane" photoflash safety covers into anti-dazzle filters

In addition to the well-understood invisible IR flash, this article discusses an anti-dazzle (a.k.a. non-blinding) coating for normal panchromatic films; which seems like a novel idea that is neglected in modern practice.

It says:

"For the time time being [1940], the new fast IR material is available only on plates, and miniature camera workers may therefore be interested in an alternative system which makes use of ordinary panchromatic negative materials and a purple-coated flashbulb, and incidentally does not possess the minor drawbacks of the IR system. This system relies on the fact that to the eye the most luminous part of the spectrum of white light is the yellow and green. A filter coating which represses this region of the spectrum and transmits only the red and blue rays will, therefore, when used in conjunction with a suitable panchromatic emulsion, be much more efficient photographically than the visual appearance of the flash would suggest."

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If there are any problems with the attachments, PM me and let me know. Someday soon I hope to (or if anyone else would like to!) get it converted into a text file.

Enjoy!



keywords: infrared coating infrared dip infrared lacquer IR coating IR dip IR lacquer invisible flash IR transmitting infrared transmitting filter Jen-Dip flashbulb dip infrared flashbulb flash bulb

[2F/2F]

Thank you for sharing this! I want to give it a try...but where to find the ingredients?

[holmburgers]

Some of the dyes appear to be available. Just google them and hit "shopping". Some however are more restricted, like from Sigma-Aldrich, where you have to be with an institution. I'm not sure what the straight-talk is on obtaining things like these.; might be worth asking some of the veterans (PE for instance).

[holmburgers]

Infrared Filter Coating for Photoflash Bulbs

Eosin 2524 - 4 grams
Tartrazine N.250 - 6 grams
Coomassie Violet R.S. - 4 grams
Lissamine Green - 10 grams
Gelatin (Nelson's Hard) - 200 grams
Glycerine - 100 mL
Water to 1 L

Anti-Dazzle coating for phtoflash bulbs used in conjunction with [panchromatic films]

Coomassie Violet R.s. - 10 grams
Gelatine - 200 grams
Glycerine - 100 mL
Water to 1 L

Formula for converting "cellophane" photoflash safety covers into anti-dazzle filters

Purple Covers:
Methyl Violet - 4 grams
Glycerine - 10 mL
Warm water 200 mL

Yellow Covers:
Tartrazine - 4 grams
Glycerine - 10 mL
Warm water - 200 mL


If anyone has sources for these dyes or substitutes, pray tell! The two part formula for the "safety covers" holds promise as these appear to be more sourceable dyes (eBay for the methyl violet and here for the tartrazine). One could dye acetate (or cellophane wrap for that matter) or some other clear plastic for use over modern strobes.

Someone in a medical discipline might be able to obtain these from a lab or university as many of these dyes are used in biological staining.

However, if a two part tartrazine & methyl violet stain will work for IR; those two are easily found for less than $15 total and might be the best bet.

[Mike Wilde]

I have a lot of stains gifted to me by a liquidated biochem research company, and some of the names on yoor formulae seem familiar to me but don't map directly to the names I have inventoried. Some dyes have many common names. I will have to search it out. I inventory them by thier CI - colour index, and somewhere have a file than gives all of the cross ref's.

If you do find them, buy about 1/10th of the formulae and scale back. I know how much dye stain is producted by .5g; and we are not talking about the old screw base units to stain, but more likely M2's and M3's and maybe 25's, and an whole lot could be done with a 100mL of bath solution.

Oh, and be sure to have a large jug of bleach on hand to clean up with, and wear a mouth and nose mask, or you will be sneezing stained boogers for days. Don't ask how I learned the last point.

[holmburgers]

Mike, thanks for the pointers, especially the nasal advice

If you look in the article the dyes have I.C.I. written after them +plus+ a number which I omitted because I didn't know better... so is that international color index? Those numbers might help you make a match.

I'm sure that many other dyes could be used but that these guys found the most 'perfect' combination, but that's not to say that others wouldn't be suitable. A source with dye transmission values could help us create our own concoction.

Please feel free to report back once you have a look at your stains.

Cheers!

[Mike Wilde]

Before we go too far on this, consider wasting an e-6 slide film.
Process it without exposing it. The result is a 'black' film.
I undertand it is substantially transparent to infrared.

Why not make a 4.5" square filter by taping two sections of this film side by side, slightly overlapped.
Then make a cardboard holder to fit a folding fan reflector to allow the light from the falshbulb to go through this filter?

The other variable we must contend with in using this 70 odd year old article, is that I am pretty sure it is talking uncoated flashbulbs.
There is a reference to dying a cellophane safety bag for placing over the flash bulb. I had never previously heard of such a device, but it makes sense).

AFAIK all 'modern' ie from the 60's to perhaps 80's flash have a coating, and the B variation ones have a blue tint to the coating to boot to yield a daylight favoured output from the flashbulb's luminous emission.

So it is possible that the amount of glycerine and liquid could be cut, because the plastic on the lamp only must be dyed.

The original 'recipes' would presumably work best with non B coated bulbs.

Concentrated dyes are unbelivably dense. I was consolidating two partially full methyl violet bottles to cut down on the differernt dye stuff bottles after initailly doing an inventory of them.

The emptied bottle had but a faint dust on the inside and dust inside the cap as well. I placed them in the bottom of the laundry sink, and turned a gentle stream of cold water onto them. A vivid purple liquid resulted, and continued to be produced for over a minute, from just the action of the dust.

[Mike Wilde]

I think the ICI reference is the name that the origainal dye manufacturer called the dyes. Modern CI number are a 5 digit identifier. The organic chemistry of dyes is far beyond my comprehesion, but it makes fascinating reading.

[holmburgers]

That's true what you say about the coatings on newer bulbs. The coating might accept the dye w/o any gelatin whatsoever.

I'm not sure on the use of slide film for the flash. I'm personally more interested in the violet stain for panchromatic materials just because I don't mind if the flash is totally invisible, just not "dazzling"! (haha, I love their use of that word)

Coupled with a flashbulb and you've still probably got a sizable guide number. Alternatively, taping a Wratten 34, 34A or 35 gel over a strobe would probably have the same effect, based off of the transmission curves.

I might try to get some methyl violet on eBay, but the supplier says that they reserve the right to ask for your company affiliation, so the same roadblocks might apply even to eBay. But who knows...

[st3ve]

I might try to get some methyl violet on eBay, but the supplier says that they reserve the right to ask for your company affiliation, so the same roadblocks might apply even to eBay. But who knows...

Probably because it can mutate DNA and cause cancer. And apparently this stuff leeches into the water supply....