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Thread: Coating blades

  1. #1
    Photo Engineer's Avatar
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    Coating blades

    For those who have been asking me via e-mail or PM, the coating blades are now for sale.

    Pictures and prices are listed at the Photographers Formulary web site under coating blades. There is also a complete description.

    Thanks for your interest and your patience.

    PE

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    Dave Wooten's Avatar
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    Quote Originally Posted by Photo Engineer
    For those who have been asking me via e-mail or PM, the coating blades are now for sale.

    Pictures and prices are listed at the Photographers Formulary web site under coating blades. There is also a complete description.

    Thanks for your interest and your patience.

    PE
    Congratulations Ron! From concept to design to production to distribution!

    I see by the Photographer's Formulary site that blades for film also are in the works....!

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    Robert Hall's Avatar
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    I would like to see a better picture. I'm still not quite clear how one would use them.
    Robert Hall
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    Technology is not a panacea. It alone will not move your art forward. Only through developing your own aesthetic - free from the tools that create it - can you find new dimension to your work.

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    ZorkiKat's Avatar
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    Hi PE

    By some coincidence, I had posted today in another forum a question asking if any coating machines were available for home-coating emulsions on film. Having nothing to do the entire afternoon and finding less film in the shelves made me ask just that. I thought that since I had a lot of antique (I would include everything non digital in that category! ) of cameras, losing film meant that they would be degraded to decorative or non-imaging (eg, as paperweights, doorstops, etc) purposes.

    I shoot mainly digital now, but I always like to use these old cameras. Developing and printing (using a method that may be tabu in this forum -wet BW photopaper is hard to come by here now) from REAL film negatives remains to be a sort of renewing, reenergising ritual to me.

    This question may have already been asked 10 million times here, but how different is coating film compared to coating paper? The coating blade seems to have been designed for paper. Will it also work for film/plastic or glass surfaces? I don't mind using colour-blind emulsions with ISO speeds (should I say Scheiner or Weston instead?) of 5-10 in old plate or rollfilm cameras. 35 mm strips would be a pipe dream -as if this whole concept isn't a pipe dream to start with- since that would require perforation...

    Another question: does the coating blade require other equipment like chillers or heated water baths in use?

    zK

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    The paper coating blade requires only a flat surface, one size bigger in area than the paper size desired for the final print. (Ie. 11x14 if you make an 8x10)

    The film blade design (and plate as well), requires that there be no scraching of the film possible. This requires another blade design. A prototype picture was posted here about 1 month ago. It may require a special chilling block, but I'm not sure yet, as I'm in the prototype stages. I've used paper blades for coating film with usable results.

    Film speeds with homemade emulsions are possible in the 25 - 100 range. I have achieved 200 with paper negatives, but at least one stop is due to back reflection. Ortho sensitivity is easy to achieve. By next year, who knows, I may have pan sensitivity.

    For more information, see my workshop description on making and coating emulsions. It is found on the Formulary site. It is in June.

    PE

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    David A. Goldfarb's Avatar
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    Congratulations, Ron, on bringing these to market.

    Here's a direct link to the page on the Formulary site--

    http://www.photoformulary.com/Deskto...ID=85&langID=0
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

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    Quote Originally Posted by Robert Hall
    I would like to see a better picture. I'm still not quite clear how one would use them.
    Me too. You can't really tell much from those...unless you already know what they look like.

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    Photo Engineer's Avatar
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    We will try to get a video demo for the Formulary site, but no promises.

    Basically, they are rectangular with an adjustable undercut on the trailing edge.

    You pour the liquid you wish to coat into the rectangular open area and as you move the blade towards you, the liquid comes out under the undercut. The height of the undercut can be adjusted by set screws from 2 mil to 20 mil (approx) and that is the method by which the amount coated is metered. At 5 mil, the 8.5" blade meters 12 ml / sq ft, and the 4.5" blade measures 6 ml / one half sq ft (approximate figures for both).

    It is very repeatable, and and a similar method was used in film and paper production for years in the early days. Something similar is used in the paint industry to test paints at a given laydown. The precise name is a 'doctor blade'. Those that have textbooks by either Wall or Baker on the early days of coating may find drawings of this type of blade in some of the texts.

    The closest analog on the internet that I found was a 4" aluminum blade for $1200. That site is no longer operating, AFAIK.

    PE

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    ZorkiKat's Avatar
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    More questions- I'd like to imagine how the thing works

    [1] In use, which moves, the blade or the material being coated? Is the blade pulled across the paper or is the paper pulled under the coater blade?

    [2] About the blade's reservoir- are the wells designed to hold liquified emulsions only in amounts needed to coat the paper size it was designed for? For example, can the 8 in model hold more liquid than needed to coat an 8x10 sheet? What if coating a longer sheet, say 8x30 instead of 8x10 is done? What is the maximum length that
    the coater can do?

    Jay

  10. #10
    Photo Engineer's Avatar
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    Quote Originally Posted by ZorkiKat
    More questions- I'd like to imagine how the thing works

    [1] In use, which moves, the blade or the material being coated? Is the blade pulled across the paper or is the paper pulled under the coater blade?

    [2] About the blade's reservoir- are the wells designed to hold liquified emulsions only in amounts needed to coat the paper size it was designed for? For example, can the 8 in model hold more liquid than needed to coat an 8x10 sheet? What if coating a longer sheet, say 8x30 instead of 8x10 is done? What is the maximum length that
    the coater can do?

    Jay
    Jay;

    Either the paper or the blade can move, but in normal use, the paper is taped down and the blade moves, by hand power, over the paper from one end to the other.

    The blade can hold enough to coat well over the 30" you use in your example, but practical considerations would prevent you from doing it in a smooth operation. This method was used with an automatic pump in early machines to produce lengths of paper thousands of feet long by drawing the paper past the blade and using a pump to keep the reservoir full.

    PE

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