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  1. #1
    Jerevan's Avatar
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    Photographs of the coating blade

    A thousand words have been written about its design, but I wonder if there is anywhere I can see good photographs (or a sketch) of the coating blade that has been constructed by Ron (and now sells at Photoformulary)?

    I found some photos at Photoformulary but they aren't very informative. Buying something for $550 plus shipping and taxes needs a bit more than this. Has anybody bought it yet, or is there anyone who will be making a review of it?
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  2. #2
    Photo Engineer's Avatar
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    I have posted several pictures of one here. I'll try to take a pic of one today and post it. It will be digital, but Sean thought that was the ultimate thumbing of the nose to digital. Take a digital picture of a new piece of analog equipment.

    The pictures I have are not good. The blades are very shiny and reflect light. I'm going to have to photograph a prototype which was not polished.

    About 1/4th of the original production run was sold. Denise Ross has said that she would try to post some comments on them. She plans on buying her second one. I have several special orders from people who have used them or bought them. Two of them are in production right now.

    George Eastman House was the first customer. They know how these blades are used at Kodak and RIT.

    PE

  3. #3
    Jerevan's Avatar
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    Thanks PE,

    it's good to know the product sells and the interest in it seems genuine! I am really interested in reading any real world experience comments or reviews. At the moment the blade is out of budget for my experiments but I am definitely am going to keep an eye on future developments. Thank you for your efforts.

    Jimi

    EDIT: Isn't it strange? I have been looking high and low, but right after I posted this reply, I found some of the photos you had posted earlier - I did a search for photographs of coating blades - and found this thread: http://www.apug.org/forums/forum42/25972-foam-brush-paper-coating-question.html
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  4. #4
    Photo Engineer's Avatar
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    Photos of coating blades

    Here are 2 photos (actually a composite of 4) taken with a digital camera of a new device for making analog photos.

    The first picture is one production run of 20 paper coating blades, consisting of 10 8x10 blades and 10 4x5 blades. At the left side of the picture is a prototype 11x14 blade. A pen is included for scale.

    The picture also includes a picture of the items you will need for maintenance which are a feeler gauge and an allen wrench. They are on the right in the first picture. At the top of the first picture are several prototype film blades.

    In the second picture, you see front and back pictures of a film coating blade. The adjustment screws are clearly seen, as are the openings for the allen wrench.

    Hope this helps.

    PE
    Attached Thumbnails Attached Thumbnails blades1.jpg   blades2.jpg  

  5. #5
    Jerevan's Avatar
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    Now that I look at these photographs, I understand better how the blade works. I was wondering how it was possible to gauge the distances given in earlier threads, but hey, feeler gauges... sometimes things don't need to be complicated, eh?
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  6. #6
    Photo Engineer's Avatar
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    If you want easy, and don't want to mess with feeler gauges, then here is something to remember.

    35 mm film is 5 mils thick. (0.005")
    120 film or 220 film is 2 mils thick.
    4x5 or any sheet film is 7 mils thick.

    So, I actually use pieces of film for quick calibration. The error introduced by the coating on the suppor is so tiny it is not worth mentioning.

    PE

  7. #7

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    As an engineer I'm feeling quite ignorant. How are these blades used. In the left photos, I see a "c"-shaped milled piece of steel with what appears to be a single blade across the mouth of the "c", forming a bow-like instrument. In the photos to the right it looks like a single blade on the "back" of the "c", leaving the mouth open.

    Where does the film-base go? Does it go in between two pieces, or does the blade skim over the film-base?

    I must say, I always visualized the blades as more squeegee-like. I saw the previous thread, but must have stopped reading it before the last several posts were added.

  8. #8

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    Quote Originally Posted by Photo Engineer
    ...120 film or 220 film is 2 mils thick...
    120/220 is typically 4 mils thick; T-MAX is 4.7.

  9. #9
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    Quote Originally Posted by Sal Santamaura
    120/220 is typically 4 mils thick; T-MAX is 4.7.
    Sal, you are right. It is 4.0. I really slipped up on that one. There is a common household product that is 2 mil. That is what I was thinking of, but I cannot remember what it was.

    Thanks for the catch!

    PE

  10. #10
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    Quote Originally Posted by Terence
    As an engineer I'm feeling quite ignorant. How are these blades used. In the left photos, I see a "c"-shaped milled piece of steel with what appears to be a single blade across the mouth of the "c", forming a bow-like instrument. In the photos to the right it looks like a single blade on the "back" of the "c", leaving the mouth open.

    Where does the film-base go? Does it go in between two pieces, or does the blade skim over the film-base?

    I must say, I always visualized the blades as more squeegee-like. I saw the previous thread, but must have stopped reading it before the last several posts were added.
    Terence;

    The blades are drawn over the support.

    In the case of the paper blade, the open well is filled with emulsion and the leading edge keeps the paper flat. In the case of the film blade, there cannot be a leading edge, as it would scratch the film, so it is open and the emulsion is poured ahead of the blade.

    An adjustable doctor blade is the trailing edge in each case and it 'scrapes' off the emulsion to the fixed height that the coater sets the blade for.

    This gap is typically 5 mils, but the range is from 2 mils to 20 mils. Often, viscosity must be adjusted for the gap width, and if the gap is large, a dam must be used to prevent premature leaking and side flow.

    A chill set block is used often for heavy film coatings, but for FB paper, the paper support will absorb most of the excess moisture and set up nicely.

    PE

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