High Precision Hand Coating Blades

Discussion in 'Alternative Processes' started by Photo Engineer, Oct 14, 2005.

  1. Photo Engineer

    Photo Engineer Subscriber

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    This is not intended to be spam. That said, here goes...

    I have just accepted delivery of 3 high precision stainless steel coating blades that allow near production quality coating in sizes of 4x5, 5x7 and 8x10. The coating thickness can be a very large range limited mainly by the 'feeler' gauges that you use to set the blade gap.

    These blades are based on equipment that we used in research at Eastman Kodak with some modifications to improve yield of usable prints in a home darkroom. They are intended for making paper prints. I am working on a similar set of film coating blades. They use no proprietary technology.

    I have no idea what they will cost in quantity, but the ones I have cost me a bundle.

    Right now, the yields of good prints are about 90% with the smaller blades, and due to a design error, only about 30% with the large blade. I am having it redesigned (it wasn't heavy enough and the end cap was not thick enough), and another one made that will coat 11x14 sheets.

    The reason for this post is to find out if there is any interest in such equipment. Not spam, but a poll to see if there is anyone else out there who wants to give up the old paintbrush or foam brush and go with professional quality. I am not taking orders.

    Anyhow, in the future, there may be a professional style coating block and a professional drying cabinet.

    Am I barking up the wrong tree? Is anyone or no-one interested?

    Your comments would be very appreciated. Thanks very much.

    PE
     
  2. Jorge

    Jorge Inactive

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    I would be interested in the film blades. I figure I have plenty on crappy negatives that I can remove the emulsion and re use the acetate to re coat if film is stop being made. Since I am working on 8x10 and 12x20 I figure a 13 inch blade would be good enough. What do you say?
     
  3. Ole

    Ole Moderator Staff Member Moderator

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    Interesting--- VERY interesting. I'll have to start selling prints one of these days, with the expenses I'm willing to take to get them just a little bit better (or weirder).

    So tell me: Would these blades be usable for coating glass plates?
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Interested if the cost isn't outrageous.
     
  5. magic823

    magic823 Member

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    Definately interested in both the paper and the film blades.


    Steve
     
  6. Kerik

    Kerik Member

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    Need more info before I can say one way or the other.
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Thanks for the feedback.

    A few answers are in order. Customs sizes will skyrocket costs. These are hand tooled and will cost enough in quantity already without getting custome sizes, so your suggestions on 'standards' will help.

    The blades are actually oversize by 1/4" for each smaller dimension (4, 5 and 8 inches) to allow for the bad portion at the edge to be trimmed off. Any length can be coated that the individual can handle. I coat a bead 4.25" wide on 5.5" x 14" sheets and can cut 2 4x5" sheets from that. Coating that uses 6 ml of melt or about 125 mg of silver. An 8x10 is coated on an 11x14 sheet and requires about 12 ml of melt or about 250 mg of silver.

    I am working on finding good subbed paper (see the other threads and my posts on this elsewhere), and finding good subbed film. Your comments on this are also welcome.

    Until I can check it out, I hesitate to use the same method to coat film and paper, but with a finely machined blade it may be possible. Stay tuned for the answer to this one.

    But, as of now, film and paper blades will probably not have the same design due to the physical properties of film and paper.

    RC paper behaves more like film. FB paper is in a class of its own. You can use the same blades for FB and RC, but will not be able to use film blades for FB. You might be able to film blades for RC. Paper blades might be used on film if things work out.

    PE
     
  8. Donald Qualls

    Donald Qualls Member

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    Umm.

    Interest, yes.

    Money and time and equipment and workspace, no.
     
  9. argentic

    argentic Member

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    Depending on cost I'm very interested.
     
  10. donbga

    donbga Member

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    Okay you've got my interest. I'll stay tuned.

    Don Bryant
     
  11. Jim Chinn

    Jim Chinn Member

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    I do not know what a hand coating blade is. Is it a blade in a jig that moves over the paper and you apply the emulsion bead? Does the blade apply the bead through holes or slot in the blade itself?

    I am also interested, especially in the possibility of coating film.
     
  12. Photo Engineer

    Photo Engineer Subscriber

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    Jim, The application of the emulsion takes place by means of a slot in the blade.

    Film emulsion making and coating is much harder than making paper emulsions and coating them. That is why I started out with paper. It is also harder to get good subbed film support as opposed to getting good paper support.

    Maybe I should ask another question here. Is there any interest in a workshop on emulsion making and coating? If so, comments on subject matter and interest would be appreciated.

    BTW, the reason I got into this is that the base of B&W products is eroding and promises to vanish much faster than you might imagine. I'm trying to do my part to 'be prepared' and to help others be prepared.

    I stated elsewhere that I started with Azo paper as it was one of the most popular and first major product to 'vanish'. I have coated 3 contrast grades of Azo type emulsion on 4 different types of paper support including the original Azo type single weight baryta paper. So, I am getting somewhere in my efforts to continue the lifetime of B&W photography.

    Maybe someday I'll have to turn my efforts to color. I hope not.

    PE
     
  13. Jim Chinn

    Jim Chinn Member

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    Besides paper, I think you might find a very large demand if a blade is able to coat glass plates that have been properly prepared. The idea of being able to possibly craft an emulsion and apply it to a small batch of plates for specific applications would be very cool.

    I for one would be very interested in a possible workshop.
     
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  15. Photo Engineer

    Photo Engineer Subscriber

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    Any of the blades will work on glass, but since coating glass is easier than coating film or paper support, you may be able to do without the blade unless you want precision.

    This method will lay down precise amounts of both gelatin and silver. And, it can be repeated every day, year in and year out, as long as you keep your blades in calibration.

    PE
     
  16. Kobin

    Kobin Member

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    I'd be interested in the workshop and maybe even the tools.

    K.
     
  17. Photo Engineer

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    Well, looks like a very low level of interest in either the blades or in a workshop.

    Since either will involve a lot of effort and expense, I guess I will not go ahead with this. Maybe this will change when more products begin to vanish forever.

    Thanks for your responses.

    PE
     
  18. scootermm

    scootermm Subscriber

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    Ill reiterate what a few have said in here... what exactly is a coating blade? do you have anything that could show what you are meaning? like a jpg etc?

    Im still confused as to what you mean by a coating blade.
     
  19. bobbysandstrom

    bobbysandstrom Member

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    also, what are we talking for PRICE? and what kind of environment is needed to produce the product?
     
  20. Photo Engineer

    Photo Engineer Subscriber

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    I'll try to explain until I get a good jpg, ok? I hate using d*****l.

    You can paint light senstive material onto paper or film with a brush, but it leaves strokes and marks. You can pour light sensitive material onto plates and let it roll around and smooth out into a layer, but how thick and how uniform is it? Well, that is up to the skill of the operator. You can dip paper or film into a tray of chemicals and put down senstive emulsion. Again, how uniform and how much.

    A coating blade is a precision instrument that places an exact amount of sensitized material in a precise location. This thickness is determined by a gap that is adjusted with feeler gauges and set screws. I use 5 mils. This places about 12 ml of solution on every square decimeter of support, and the coating is uniform at 5 mils. I have coated from 2 mils to 10 mils with these devices.

    I can coat 4x5, 5x7 and 8x10 sheets of paper and film with a 1/4" selvedge that can be cut off. I am trying to get an 11x14 inch blade.

    The intent is to have available a method for coating sheets of contact and enlarging papers and sheet film or MF film strips if or when the B&W materials become unavailable. I'm looking ahead to that day and see no technology out there for good quality hand coatings of convential materials. I am trying to supply a series of simple emulsions for this as well.

    The reason I can do this is that at Kodak, we in Research had to make high quality hand coatings when using small samples. The coating machines were too big. So, I decided to re-engineer what I knew from those days and make something for myself. Along the way, I made a series of emulsions and coated them to prove the concept. The blades and the emulsions are the result of my work.

    At the present time, I get near production quality matching Ilford MGIV grade 2 in 4x5 and 5x7 about 90% yield or greater. My current best paper is a contact grade Azo type work alike. I am close to an enlarging paper as well, but the contrast is a bit low for my tastes. The speed is exactly the same as the Ilford MGIV.

    In 8x10, I get about 30% yield due to a design fault of my own making. I am working to fix this up.

    Devices similar to these are used in the paint industry and are known as doctor blades. I would post a reference and URL, but the site seems to be off-line right now. A google search for Doctor Blades will turn up some hits.

    Anyhow, the lowest price I could find was in the range of $1200 for a 4x5 blade, and that is outrageous. My design will cost far less than that and works as well or better. I am willing to find a distributor for them, and then leave it up to him after I get an initial order for them out to whoever this company may be. I don't want to sell them myself, but do want to recoup my losses / expenses in this project. But, if there is little interest, then I will simply not go to the trouble until the world beats a path to my door.

    In the mean time, I am cranking out my own B&W prints on my own B&W paper.

    PE
     
  21. Photo Engineer

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    As for price, the machine shop has not gotten back to me yet. It will probably be about $300 for a 4x5 blade, but IDK. That is a lot less than the $1200 that was the miniumum I could find currently available.

    The environment is a normal darkroom. I use my darkroom with a sheet of metal for a coating surface and paper or film for the substrate to coat on. I buy Strathmore Smooth paper in 11x14 at the local art store. It works just fine.

    The only extra equipment that I have is:

    Stirring hotplate to reach higher temperatures for making emulsions.
    Good balance for weighing out chemicals.
    Pet Syringes for injecting chemicals in precise amounts in the dark.

    And, all of the chemicals to make an emulsion such as silver nitrate, sodium chloride, sodium bromide, potassium iodide, and gelatin.

    PE
     
  22. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Still interested. I'm wondering if you might not find more demand from handcoaters in larger sizes, since it is more difficult to sensitize a large sheet evenly than it is a smaller sheet with 19th-century methods.
     
  23. Peter Schrager

    Peter Schrager Subscriber

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    Workshop

    PE-don't give up on us so fast. I think that his might make for a great workshop.
    Where are you located? I might never do my own coating but I just might need to so at some point. Keep us informed please.....
    Thanks, Peter
     
  24. Jorge

    Jorge Inactive

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    Whoa, hold on! dont give up just yet. I might not be able to take the workshop but I am definitly interested in the blades for film. Let me tell you, doing this over wet plate collodion seems a lot easier, expensive at the start but I imagine after a few years the blade will pay for itself, specially when they stop making film.
     
  25. Jim Chinn

    Jim Chinn Member

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    I think it will be hard to get a lot of committment from people who can not see a blade or how it works. If you were able to demonstrate the use of one at the APUG conference (part of a workshop) you could quickly gauge real interest. Also it only takes a few individuals to see something and be excited about the posibilities. Once they start discussing it here, LF forum, Photonet, the Alternative Phtography site etc you will get real interest. The key is show it to a few key individuals who's opinion everyone respects.

    You may just create a who new sub group of analog practioners who coat all their own silver film and paper as a more hands on approach. Like those nutty Dageurreotypists and and wet plate folks. :tongue:

    I agree with David that something along the lines of 11x14 would be of interest to a lot of alternative folks.
     
  26. User Removed

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    AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH! DONT SAY THAT! :sad: