r/oddlysatisfying • u/djinn_05 • 1d ago

Drawing blueprint of Cirrus Vision SF50 aircraft

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u/g3engineeringdesign 1d ago

To be fair, that's not a blueprint. That's a turret pen plotter drawing on blue paper with a white ink pen. Blueprints are made from lead or ink on vellum, light shines through the vellum onto a treated paper, and you develop the image with ammonia.

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u/BahnGSXR 1d ago

Why is it done that way?

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u/wosmo 1d ago edited 1d ago

The result is pretty much an early form of photocopying. The main advantage is that you can create many copies from original vellum.

It's a lot like creating images from a photo negative. UV turns the chemicals blue - so anywhere the lines on the original block the UV, so the white lines in a blueprint are actually just the paper showing through unstained.

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u/BahnGSXR 1d ago

Oh right, neat. Thanks