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  1. #11
    Rick A's Avatar
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    I picked up a ton of screenprint stuff a couple of years ago thinking it would be fun, and a natural extension of my darkroom work. Now I have a ton of unused screenprint equiptment sitting in my attic. I even bought an 18"x24" repro camera to make my copywork, thats sitting in the basement. Oh well, at least my wife isn't giving me any grief about my toys. Anybody want a giant repro camera?

    Rick

  2. #12
    Steve Smith's Avatar
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    Quote Originally Posted by Ian Grant View Post
    Your own field is more specialist and while+/-0.25mm sounds a tight tolerance it's nothing in comparison to photo-resists used for micro-chips.
    That's true but it is a very tight tolerance when you are trying to cope with screen stretch on an 18" x 24" sheet.

    For really critical work we modify the artwork to compensate and on some machines it's not linear in either direction.


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  3. #13

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    Quote Originally Posted by AlexG View Post
    I've been wanting to get into screenprinting for a while.
    There is a nice short how-to outline of the process in a photography book by Michael Lang... something - I don't recall the exact name... perhaps someone will know, otherwise I can go look it up in my library later.

    Perhaps this will be all you need... but you still need the emulsion, and as has been pointed out there are two (basic) types... one orange with dichromate and the other white being a normal photographic emulsion... unfortunately, they are both called "emulsion" and even "photo emulsion", so there is some confusion... Wasn't this process called photolithography?

    Anyway, you might want to have a look at that book....

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  5. #15
    glbeas's Avatar
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    This is the manufacturer I'm familiar with from my screen printing days. This is the stencil info page.
    http://nazdar.com/screen_printing_pr...tion&attrIDs=0
    Gary Beasley

  6. #16

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    Quote Originally Posted by glbeas View Post
    This is the manufacturer I'm familiar with from my screen printing days.
    That seems to be a diazo based material.
    I have never used these processes, but another name that comes to mind is "Ulano" or something like that.

    But come to think of it, the OP said he had seen online manuals, and they were using a "liquid light" type product... yet he then asked if a liquid light type product can be used... (?)!

    Perhaps the OP simply wants to communicate with other people actually doing that processes... I don't, so I will get out of the way.

    Ray
    Be free of all deception, Be safe from bodily harm
    Love without exception, Be a saint in any form
    (Patti Smith)

  7. #17
    Ian Grant's Avatar
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    Ray, I suspect the confusion is because screen printers use an emulsion, albeit usually only sensitive to UV light and with no silver, but Rockland Colloids still make PRINTSCREEN which is on the same page as Liquid Light on their website and can be exposed by contact printing a Line neg using a Halogen lamp rather than UV.

    But at one time they did have an enlargement Screen-print emulsion but I don't have any details here, I may have saved the thin Catalogue in the UK.

    Ian

  8. #18
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    There are basically 4 different ways to use these photo systems.

    The Dichromate system, painted on a screen, hardens the gelatin imagewise using UV or daylight for exposure and is developed by a hot water rinse which removes gelatin where exposure did not take place. The remaining image can be used as-is, or it can be inked and used as a resist to allow the inked image to pass through the screen to a reciever. That accounts for two possible methods.

    A silver halide emulsion can be used the same way, coating a screen and when exposed will yield an image on the substrate or screen in this case. But, since silver halide does not harden gelatin unless you use a tanning developer, if you wash with hot water, the image is lost. Therefore you can either harden the gelatin beforehand and then retain the entire image, or you can use a tanning developer to harden the gelatin imagewise to retain only the developed image.

    With the first way here, you cannot pass ink through and it will not act as a resist, only a substrate for the entire image. With the second way, you get a resist with pores created imagewise just as with the dichromate system. All of these methods yield fine images, the differences being exposure time and light type and processing method.

    We used to make 3 or 4 color decals using these methods and printing onto transferrable blank paper decal sheets. We also made multicolor t-shirts this way. That was so long ago, it was back when there was no digital at all! We kept a bolt of cheap fine silk in the shop and several types of cloth as well for achieving the different textures that customers wanted. This used to be a service of some photofinishers back then.

    PE

  9. #19
    Ian Grant's Avatar
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    Your 4 ways misses Etch Bleach Ron (PE) where an image is processed and the developed part of the image removed by the Etch-Bleach which is usually Acetic Acid/Cpper Chloride/Hydrogen Peroxide.

    Ian

  10. #20
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    Well, I should add then that the post refers to the methods I have used. Sorry. I am not even remotely familiar with the method you describe. It must be an archaeological curiosity for you to know about it.

    PE

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