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| Authored by: UncleVom on Sunday, April 22 2012 @ 04:58 PM EDT |
My exposure to such stuff has been through the Architectural and Engineering end
of things.
The original blue prints were blue background with white lines. I have not seen
such a process used, except for artistic reasons, since the early 1960's.
There was at some point a technological change to "white prints" or
translucent background with black, blue or sepia lines.
All the above were direct contact prints made from an original drawing over a
photo sensitive paper that was than exposed to a light source and then the areas
activated and fixed by a chemical solution, often ammonia based.
Such drawings wherever they occurred in the development process were
"working" copies for use in the field, for review, contact copies, for
mark-up or for back-up preservation.
What finally killed the diazo prints and from what I can see they really are
dead was cost. Materials cost, labour cost and time consumed.
The inkjets and large format laser printers could crank out copies on plain
paper far cheaper. Yes they can do mylar prints using a sheet with a matt side,
I've not seen linen used as a print medium beyond the 1930's.
There maybe somewhere some specialist companies that still use the old methods
for some historical reason or another, maybe they like the smell of ammonia in
the morning. I have not been exposed to such operations in at least 15 years.
I think the "blueprint" term has been widely used over the years
merely to indicate a reproducible plan, formula, or sequence of operations of
any kind, and no longer is tied necessarily to drawings and their reproduction.
Now about those swipe gestures using chalk, chalk board (Slate?) and brush. ;-)
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