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Thread: DIY Dark Slides

  1. #21

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    Re: DIY Dark Slides

    Just out of curiosity, does anyone know what the dark slides from nearly century old wood and metal film holders were made of?

  2. #22

    Re: DIY Dark Slides

    Quote Originally Posted by Steve Goldstein View Post
    It looks to me like therr might be some confusion here regarding the term “dark slide”. In some countries this term refers just to the flat black that sheets, often with handles of some type, that are used in film holders. In other countries it appears the term is applied to the entire assembly, hence the term “double dark slide or DDS.

    I could be wrong, but I believe what Intrepid have been having trouble with is manufacturing the complete film holder, not the dark slide itself.
    The problem with the entire double sided film holder and not the dark slide itself is the impression I got as well Steve.

    I did some digging into FR4 material online last night and it appears to be a circuit board material that has a fiberglass component and it comes in various colors and grades as well as thicknesses including the 0.9mm designated as the correct one for dark slide application. That said, finding which "grade" is the correct one and a vendor where you do not have to acquire an entire pallet at thousands of dollars capital outlay would be great. Given we are in the process of a trade embargo with China and this appears to be here much of what I found online is shipped from I was wondering if anyone has a source for a stateside vendor of this material that we could consider initially for a sample evaluate and test and potentially later on for a supply size that is manageable for the interest expressed. Sometimes these companies have internal facilities for contracting the cutting. I am under the assumption that the majority of the interest in dark slide replacement will be with the standardized 8x10 Fidelity / Lisco holder. Folks with wooden holders or other brands of holders with differing dimensions may want to have their own dark slides cut themselves. Kumar located Toyo replacement 8x10 dark slides for me as well as the 90 degree angle screws for these holders.

  3. #23

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    Re: DIY Dark Slides

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    so here is where I am on this project-
    from an intact dark slide, a template was made. From the template I used a templating bit on a router and milled the only material I had on hand that I thought might work. I also have 4 more materials coming from McMaster and will be getting some edging material to finish off the pull tab (not pictured- but planning to do a traditional loop-style pull with the plastic edging I have coming). The pics at this point are the template which gets double sided tape in each corner to hold the material in place during routing, the white strips are shims so the material sits flat during the cutting process. Pic 2 is the first prototype made from CPVC. The pros of this material- cheap ($7.27 for a 12"x12" sheet),machines very nicely, very tough and flexible, the correct 0.030" thickness, slides in and out of a fidelity holder very smoothly, and from what I can tell in a crude test in my darkroom, is completely non-transmittant to light. The cons so far- a bit static-y and the color is gray, not black (not sure if this will affect function at all, but it looks kind of cool). Ill continue to update this post with what I figure out from other materials and I plan to do film tests at some point in the near future- but would like to find some cheaper film than what I have on hand to do that with. More to come...

  4. #24

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    Re: DIY Dark Slides

    Cool, thanks for sharing your results.
    I've always used 1/32" Garolite XX , but have heard that some batches are not quite opaque.

  5. #25

    Re: DIY Dark Slides

    Quote Originally Posted by Colin Graham View Post
    Cool, thanks for sharing your results.
    I've always used 1/32" Garolite XX , but have heard that some batches are not quite opaque.
    That is what I found with my iteration. I was lured into the conveniences of being able to acquire inexpensive black materials only to find that the requirements of 100% light blockage was never contemplated by the manufacturer or the seller.

    As a result I am convinced that the optimal dark slide material must have a fiberglass layer for strength and a secondary layer for light tightness all in a 0.9mm thickness and black in color. FR4 seems like the ticket. I am going to see if I can get a sample of this material to see if Eric can do a test on it.

  6. #26

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    Re: DIY Dark Slides

    Testing is important, yes. There can potentially be variations within a single sheet of material. A 15 minute soak in direct sunlight is the most my filmholders will ever endure, so that's the test I use.

  7. #27
    おせわに なります! Andrew O'Neill's Avatar
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    Re: DIY Dark Slides

    Quote Originally Posted by Vaughn View Post
    And I have 8x10 and 11x14 holders with metal darkslides -- definitely heavier, but no worries of light leaking thru them! Tough sonsofaguns, too.
    I have a few 8x10 holders with metal slides. They are my favourites.

  8. #28

    Re: DIY Dark Slides

    After some research on the topic and the advice of a highly skilled machinist friend, I have decided to proceed with anodized aluminum for dark slide Fidelity / Lisco 8x10 holder replacements. Fortunately Kumar was able to get me hooked up with Toyo 8x10 replacement dark slides and holder pins at a reasonable price. Should be good to go after this iteration.

  9. #29

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    Re: DIY Dark Slides

    So after receipt of the other material candidates from McMaster I have the following to report. Items received were the black deldrin, two types of nylon (black and black slippery) and garolite sheets. The deldrin and both nylon samples failed the light transmittance test. In this test I go into the dark room with a high intensity LED flashlight with a light tight shroud over the front and hold it to the back of the sheet and see if light gets through to the other side. Only the garolite and the aforementioned CPVC sheets (see earlier posts) passed this test. Both were found to be inexpensive, light tight, easily machinable and the correct 0.030" thickness which allowed them to easily be manipulated in the slot of the film holder. My hope was to make the pull section with a plastic push on trim (item 86875K92) but it seems a bit too flexible and so far I haven't identified an adhesive that can secure it to either material. I may just machine the pull tabs in the final iteration or see if I can find some aluminum edge material that will stiffen the tops and make them easier to pull. I will be taking film this coming weekend and doing the final light test by exposing it, cutting it in two then placing one half of each piece behind the slide candidates in the holder for exposure of the closed assembly to the sun for 10-15 mins. I report results after developing. I don't have a densitometer, but I think I should be able to see fogging if it happens.

  10. #30

    Re: DIY Dark Slides

    Quote Originally Posted by eric black View Post
    So after receipt of the other material candidates from McMaster I have the following to report. Items received were the black deldrin, two types of nylon (black and black slippery) and garolite sheets. The deldrin and both nylon samples failed the light transmittance test. In this test I go into the dark room with a high intensity LED flashlight with a light tight shroud over the front and hold it to the back of the sheet and see if light gets through to the other side. Only the garolite and the aforementioned CPVC sheets (see earlier posts) passed this test. Both were found to be inexpensive, light tight, easily machinable and the correct 0.030" thickness which allowed them to easily be manipulated in the slot of the film holder. My hope was to make the pull section with a plastic push on trim (item 86875K92) but it seems a bit too flexible and so far I haven't identified an adhesive that can secure it to either material. I may just machine the pull tabs in the final iteration or see if I can find some aluminum edge material that will stiffen the tops and make them easier to pull. I will be taking film this coming weekend and doing the final light test by exposing it, cutting it in two then placing one half of each piece behind the slide candidates in the holder for exposure of the closed assembly to the sun for 10-15 mins. I report results after developing. I don't have a densitometer, but I think I should be able to see fogging if it happens.
    Great!

    May I suggest a test I used for being able to ascertain added FB+F for the infrared light source on my infrared monocle.

    Put a piece of black electrical tape on the emulsion side of your sheet film in total darkness and insert the film with the tape into the holder. Without making an exposure of the sheet film leave the holder with the test slide material inserted facing the sun for 15-30 minutes. Pull the tape off of the film before you develop the unexposed film and you will have a sharp edge of potential density to evaluate or not. Put this over a light table and if you cannot see any hint of density ascribing the space the electrical tape occupied on the film, you should be good.

    I contend that the only acceptable test result is zero added density irrespective of how small it may be. Why? because it its likely a linear relationship with increased time exposure to the light source and that is simply unacceptable. Ran into this issue with the density added by the infrared monocle IR light source which glows a red color when it is on. There was a increase in density that is easily remedied by bounding an LED IR light source off of an adjacent wall so only IR comes into the viewing area allowing one to take out the batteries on the monocle IR light source. Yet many folks on this forum commented that although some density was added using the monocle IR light source, it was not enough to be worried about which begs the question, when it some density too much density?

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