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Thread: Blue prints

  1. #1
    Uncle Goose's Avatar
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    Blue prints

    Ok, I suppose blueprints are exactly the same as cyanotypes right? So I wonder, how did they make those blueprints? I suppose they used some sort of machine for this? I've looked at some old blueprints and the coating seems to be incredible evenly over the whole sheet (and it was a large sheet). So how did they coat the paper? I suppose dip and dunk or something like that? Just wondering.
    Sure, I could give you a boring explanation who I really am but I rather let the Origami do the talking.

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    There was a machine with rollers and chemicals. Take out a large sheet of paper (in daylight), put the original transparent sheet on top, feed it into the first roller.... then when it comes out, feed just the exposed paper back into another slot and it comes out of a third slot sort of damp. Let it dry for a while and it's ready.

    It was a predecessor for xerox copy machines. It was handy because it can handle huge size.
    Develop, stop, fix.... wait.... where's my film?

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    Uncle Goose's Avatar
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    That I suspected already but I would like to know what machines they used to actually coat the paper, anybody has photographs of such installations?
    Sure, I could give you a boring explanation who I really am but I rather let the Origami do the talking.

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    This may help, even though it doesn't really answer your question. http://www.engineersupply.com/How-To...lueprints.aspx

    The coated paper appears to have "come from a factory in sealed container". The manufacturing details for the sensitized paper, which I think you are most interested in, remain a mystery.

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    DWThomas's Avatar
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    Yes, in the machines I saw/used back in the 1960s, the paper was already coated and came in standard cut sizes and rolls. I seem to recall nasty ammonia fumes from the development process.

    Obviously somebody coated the stuff, but as a dedicated production process.

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    True blue prints produced a negative image of the original with white lines on a blue background.

    Blue line prints replaced classic blue prints probably 45 or more years ago. Blue line prints produce a positive image - blue lines with a white backgroung. The blue line prints utilize the diazo process. The paper is purchased precoated. While it is light sensitve, it rquires a very intense light source. As stated earlier, it uses ammonia as the developing agent. There is no fixing required and image is not very permanent.

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    Quote Originally Posted by DWThomas View Post
    ... I seem to recall nasty ammonia fumes from the development process.
    ...
    I lived in the mimeograph era, but was too young to have anything to do with blueprints (other than seeing some under my Dad's arm when he was going/coming to/from work. I remember, though, always inhaling deeply the fumes on the mimeograph paper. Was that the same (ammonia), or was that aclohol? I just remember the "huffing" and not the identity of the fumes.

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    The paper came already coated as already said. The package looked like a giant version of a ream of today's Xerox paper, except one side of paper was faintly yellow or blue.

    I *think* it's ultra-violet sensitive. I don't recall paying any particular attention to light sensitivity while handling it but I also recall putting some objects on it and leaving it out under direct sun for few minutes to get images of the objects burned in.

    It was at least 35 years ago.
    Develop, stop, fix.... wait.... where's my film?

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    The Blue Print is Alive and Well

    As a land surveyor I make blue prints every day to reproduce copies of my final plats.

    We do use AutoCad for drafting and plot on a large format HP inkjet printer onto mylar.

    After I sign and seal the original we make blue line copies for our clients.

    It's an incredibly cheap and productive process.

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    Quote Originally Posted by Born2Late View Post
    Blue line prints replaced classic blue prints probably 45 or more years ago. Blue line prints produce a positive image - blue lines with a white backgroung. The blue line prints utilize the diazo process. The paper is purchased precoated. While it is light sensitve, it rquires a very intense light source. As stated earlier, it uses ammonia as the developing agent. There is no fixing required and image is not very permanent.

    I remember running a diazo engineering drawing copy machine in an engineering office the summer before my senior year in high school. That would be about 57 years ago. The worse part of the job was pouring the ammonia solution into the machine once or twice a day. I believe later machines took the ammonia out of a container with no pouring.

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