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  1. #1
    holmburgers's Avatar
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    'Dazzle-Free Photoflash Photography' - Infrared-Transmitting Coating for Flash Bulbs

    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.

    --------------------------

    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."

    --------------------------

    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

  2. #11
    holmburgers's Avatar
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    Well, that certainly sucks. But minute quantities, responsibly handled, aren't a problem. For every gram of the stuff I can't buy, some large industry is probably buying kilos of it and disposing of it improperly.

  3. #12
    Mike Wilde's Avatar
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    I have about 100 g of the Methyl, and lesser amounts of other dyes and have mailed dyes to the US for people from here without any apparent problems. PM your postal address, and I will mail you a few 5g or less little jars or dyes to experiment with. It might take me til Christmas though. My wife and son are rehearsing for a soon to open play, and I am left to work and juggle a lot of the household tasks (more than my typically equitable share) for a little while.
    my real name, imagine that.

  4. #13
    Mike Wilde's Avatar
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    Oh - another idea - Wilton paste food colouring is mostly a concentrated food class dye set in glycerine. Not sure about the spectral performance, but they should be widely available.
    my real name, imagine that.

  5. #14
    holmburgers's Avatar
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    Thanks Mike, PM sent.

    Also, for others interested, it appears that a good number of dyes can be had on eBay at reasonable prices from various lab liquidators. You might not have the pick of the litter, but wait long enough and I bet the right dyes come around. Same goes for sensitizing dyes, dye-imbition dyes, and all the like.

  6. #15
    Mike Wilde's Avatar
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    I was readng Mees 'From Glass Plates to Ektachome' on the weekend (Thanks for the loan, David William White), and there is a chapter on sensitizing dyes.

    There is a reference to a paper that Mees published in some scholarly journal in 1920 about the absorptive propoerties of many dyes of interest for photo sensitising.

    The organic chemistry discussions on thier synthesis flies miles over my head though.

    Chis - I have packed 6 small plastic bottles of different dyes and a number of nose and mouth surgical masks in a bubble envelope; all that remains is to get to a postal outlet for the customs declaration label and postage.

    One of the things I tried to send you was an effectve yellow. Apparently yellow is not a popular biological stain, because I have lots of outher colurs, but short on yellow. The actual yellow I had is closer to orange, but there is a red dye included that is an indicator as well, and at moderate pH in my tap water is very yellow.

    I hope you have fun playing when you get these. Be warned that from my past experience with shipping to/from the midwest US from where I am there seems to be postal black hole that makes packages take 6 weeks.
    my real name, imagine that.

  7. #16
    holmburgers's Avatar
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    Mike, thanks, I can't wait!

    Any chance you could scan that reference paper? That might be a very useful resource. Perhaps I can trot down to my local biblioteque and check it out myself.

  8. #17
    Mike Wilde's Avatar
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    One of the references is circa 1909 'an atlas of absorption spectra' cek mees. I thought there was one circa 192's but cannot find it via usual web search methods.
    my real name, imagine that.

  9. #18
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    IR flash bulbs

    I actually have a couple boxes of IR flashbulbs (I use flashbulbs). This article pretty much confirms what I thought. They are regular flashbulbs with a black coating that only allows IR to pass. That being said, I guess a regular flashbulb would do as well in IR photography-just not all stealthy and cool-looking.

  10. #19
    holmburgers's Avatar
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    Color Indices

    Lissamine Green = either CI Acid Green 50 or CI Acid Green 16
    Methyl Violet = C.I. Basic Violet 1
    Eosin 2524 = C.I. Acid Red 87, D&C Red No. 22 [probable]
    Tartrazine = CI Acid Yellow 23
    Coomassie Violet R.S. = CAS: 74968-14-2 [the index number might be CI 24200]
    Coomassie Blue = CAS: 78642-64-5, C.I. Acid Blue 92, Wool Fast Blue R

    These were provided by a confidant who is better versed in dyes than I.

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