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Thread: Coating blades

  1. #1
    Photo Engineer's Avatar
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    Coating blades

    Friday, I took delivery of the first production quality run of 10 4x5 paper and film blades and 10 8x10 paper blades. These will allow coating very high quality hand coatings of alternative photographic chemistry or silver in gelatin.

    I also have a prototype 4x5 film and plate blade, and a prototype 11 x 14 paper blade now.

    So, I spent my day calibrading and testing. The results show that the production blades appear to be within specs.

    The film and plate blade will need some slight modifications, but appears to be capable of 35mm, 120 and 4x5 film and 4x5 plate coatings. The length planned on will be about 2 feet of film or 1 (maybe 2) plate(s) at a time.

    The 11x14 blade worked perfectly with one proviso. It was the first time I had handled that monstrosity and I was a total klutz. I therefore produced a 'ramp up' in quality from crap to acceptable in 3 sheets and I ran out of test melt, but it does work and being the klutz that I am, I'm sure with some practice I'll be doing just fine with 11x14 size. (my coating plate was only 11.5" x 13" so the paper overhung the plate by 1" in one dimension anyhow, so I have to get a new plate as well)

    Anyone interested in 16x20?

    The 4x5 blades weigh about 420 grams, the 8x10 blades weigh nearly 800 grams and the 11x14 blade weighs nearly 1 kg. This is for stability purposes.

    I am going to start writing up a manual for both calibration and use, along with some pictures of the blades in action. They will be available at the workshops this summer and fall.

    Thanks to all who showed interest in this. Thanks for all of the E-mails, PMs and other support.

    PE

  2. #2
    Shinnya's Avatar
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    Ron,

    How much is 8x10 blade? I am interested in it, but of course it depends on the price...

    Also, is it something you can take some images of? I am curious to see them.

    Let me know. Thanks.

    Warmly,
    Tsuyoshi
    ----- P R O J E C T B A S H O -----
    Re-introducing Photography to Philadelphia
    Summer '11 Photography Workshops

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    Quote Originally Posted by Shinnya
    Ron,

    How much is 8x10 blade? I am interested in it, but of course it depends on the price...

    Also, is it something you can take some images of? I am curious to see them.

    Let me know. Thanks.

    Warmly,
    Tsuyoshi
    I'm working on prices right now.

    I have posted an image of one of them in this forum in another thread.

    PE

  4. #4
    JG Motamedi's Avatar
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    I look forward to hearing more...

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    I'd be interested in some details on your coating equipment and techniques - maybe with some pictures. Any chance of an article on the subject?

  6. #6
    David A. Goldfarb's Avatar
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    Sounds great. I'm looking forward to hearing more.
    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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    Mick Fagan's Avatar
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    Sounds good, looking forward to the completion of your testing.

    Mick.

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    I spent the evening coating. They are drying right now.

    I'm about to start writing the manual for calibration and use.

    Pictures are posted elsewhere here on APUG. Please refer to them until I can do more. I've been very very busy as you can imagine. I hope to have a complete writeup within a week or two along with prices.

    Basically a 4x12 sheet of paper uses 6 ml of emulsion to coat. An 8x12 sheet uses 12 ml of emulsion. The 4x5 (4x12 sheet) yields nearly 100% usable material with 2 4x5 prints on each sheet, and the 8x12 yields about 90% usable material as one 8x10, but 100% if you are willing to cut out defects in the other 10% and use that as 5x7 or 4x5 or as test strips. The quality is very nearly equal to what you buy across the counter at your photo shop. Hardness is good, with prints withstanding up to 75 deg F. I use Dektol, stop and hardner fix.

    The plate and film coatings are more of a problem due to the glass and film support. The 11x14 blade uses paper bigger than my coating area by 1" on one side and 1/2" on the other, so I'm running at less than optimum there. Give me some time to work things out. I have to build a new coating area to give the 11x14 blade a fair workout. In the mean time, it is klutzy for me to use and so my coatings are less than optimum. Give me some time and I'll be doing 16x20.

    You should know that this method has been used in the industry to machine coat up to 40" paper and film about 100 years ago, so it is nothing really new, I have only modified the method to allow several different types of hand coatings of high quality to be made by the average darkroom worker.

    There is a similar blade available for the paint industry for testing paint layers. It is made of aluminum (unsuitable for silver gelatin) and is only 4" wide. They wanted $1200 for it. Mine are going to be a LOT less expensive, if the figures I have work out the way I think. The price and the aluminum construction are what started me down this path, as I knew it could be done.

    One other thing. I have found how to 'retouch' the wet coating and this will improve the yield on the 8x10 coatings. I'll be teaching that method as well. I don't have to use it often, but it does work and you cannot see it in the prints.

    Construction is 308 stainless steel. All ancillary parts such as screws and end caps are stainless as well. Contact surfaces are highly polished for elimination of scratches, and every blade is symmetrical. That means that when you buy one, you actually get 2. So, if one side gets scratched or dented, flip the blade and keep going, you have 2 blades in one. The 8x10 blades have two surfaces to the end caps, so that you can coat with a wide or knife edge for finer tuning, and the end caps are removable so that if they need replacing you can get new end caps at very low cost. Our blades at EK were not like this, so if they got dented, we continued coating with streaks or got a new blade. Also, they were not adjustable, so we had to keep a shelf full of individual blades.

    I've tried to keep everything in mind to make this simple, convenient and as inexpensive as possible. IDK if I have, but if I have not, I'm in deep s**t with my wife for spending so much on this little project of mine. lol

    We will end up using them as door stops in that case.

    Thanks for the support.

    PE

  9. #9

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    SO how much are the 11x14 blades for film?

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    Quote Originally Posted by Jorge
    SO how much are the 11x14 blades for film?

    Jorge, I have only one prototype with no real quantity price. Also, I have not checked it out for film use, so I will not guarantee that it will work. I may have to design a different type of blade.

    PE

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