# Were blueprints really blue? **URL:** \ **Category:** Factual Questions\ **Created:** [December 30, 2013, 4:57am UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459 "2013-12-30T04:57:23Z")\ **Posts on this page:** 13\ **Page:** 3
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [December 30, 2013, 11:32pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/41 "2013-12-30T23:32:01Z")
> [@Tim\_R.Mortiss](#): > > I was a draftsman in Chicago in the late 70s. We had honest-to-goodness blue blueprints then. What did you draw? Machines, buildings, boats/ships. other? Wondering if the white on blue/blue on white was a matter of industry. With blue-on-white, the light PREVENTED the color change - a sheet allowed to get too near the machine would turn completely blue; hence mt suspicion that white-on-blue was more expensive - it turned the entire page blue. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [December 31, 2013, 2:09am UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/42 "2013-12-31T02:09:07Z")
> [@usedtobe](#): > > What did you draw? Machines, buildings, boats/ships. other? > > Wondering if the white on blue/blue on white was a matter of industry. > > With blue-on-white, the light PREVENTED the color change - a sheet allowed to get too near the machine would turn completely blue; hence mt suspicion that white-on-blue was more expensive - it turned the entire page blue. Buildings. Specifically, one building, the First National Bank of Chicago building. Every damn floor. And they were mighty similar! It was the most boring summer job ever and nearly made me give up on becoming an engineer. This was at a small architectural engineering firm that probably did not have the latest and greatest technology, duplication-wise. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [December 31, 2013, 5:31am UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/43 "2013-12-31T05:31:04Z")
My very first job, when I “ran away from home” to NYC in 1964, was as an operator of a blueprint machine. It was an easy skill to learn, and paid $60/week. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [December 31, 2013, 6:01am UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/44 "2013-12-31T06:01:11Z")
Lots of blue on white was the original process, used in the 19th century. Diazo and ozalid processes, producing blue on lots of white, was the successor process. Introduced in the 1940s, it took hold in the 1960s. There was also a brown on white process that some commercial printers used for final proofing of the negatives for a booklet, magazine, etc. I remember those having a not-unpleasant smell. The black-and-white chemistries, used for real photography and later for commercial printing processes (Velox prints and the like), required silver compounds that were too expensive for such large sheets of “throwaway” product. Until xerography. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [December 31, 2013, 3:54pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/45 "2013-12-31T15:54:55Z")
> [@JWT\_Kottekoe](#): > > When I worked in construction and later in electronic design in the early 1970’s we used diazo prints (blue lines on white paper). They were still called “blueprints” by everyone I knew. In those days Xerox machines were already ubiquitous, but they were expensive and were limited, in my experience, to small formats like 8.5 by 11, wholly unsuited to large engineering or architectural drawings. I used a Diazo machine as late as the mid-80s. One time somebody paused it too long and the web belts that drove the paper across the light source overheated and burst into flames. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [December 31, 2013, 4:13pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/46 "2013-12-31T16:13:27Z")
> [@Joey\_P](#): > > So why do that over a photocopier or mimeograph machine? Is it just that that industry had been using them for so long and that’s what they were used to? Those machines have been around since the '70’s/'80’s and are much faster. > [@Musicat](#): > > Try making a copy of a 11" x 14" music score on your average Xerox machine, using heavy paper for the copy. Or even a common music part size at the time, 9.5" x 13". Easy on a Diazo machine, impossible on most Xerox ones. We could make a 4-page music part, 13" x 38", on heavy paper, in one piece (and fold it afterwards). In addition, even when Xerox copiers were available, they weren’t necessarily to scale or accurate enough for blueprints. A friend who was a draftsman told me this and I didn’t believe him, so I copied a grid and held the original to the copy against the light, and sure enough, they didn’t quite match. That was mid-to-late 70’s. Things may be different in the digital world. I saw lots of blueprints as a kid, since my father was a patent attorney. But the most interesting ones I saw were at the big loft apartment of a bunch of artists, again in the late 70’s. I guess they’d gotten a lot of blueprint paper on the cheap and used it as an art medium, lying naked on the paper. Unfortunately, I missed the “shoot” and only got to see the results, but the results were impressive enough. 🙂 ---
**Author:** ![Siam\_Sam](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Siam\_Sam](https://boards.straightdope.com/u/Siam_Sam)\ **Post date:** [December 31, 2013, 4:14pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/47 "2013-12-31T16:14:59Z")
In Thai, they’re called “greenprints,” but I don’t think I’ve ever seen any to verify their color. ---
**Author:** ![Patch](https://avatars.discourse-cdn.com/v4/letter/p/a183cd/32.png) [@Patch](https://boards.straightdope.com/u/Patch)\ **Post date:** [December 31, 2013, 4:48pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/48 "2013-12-31T16:48:45Z")
> [@Old\_Eel](#): > > Blue blueprints may have been phasing out in the 1970’s, but I still saw plenty of new blue ones in that time. I dealt with blueprints in the mid 90’s for the military. Hell, I even had a consultant deliver a set three years ago. The smell brought back so many memories. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [December 31, 2013, 7:23pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/49 "2013-12-31T19:23:45Z")
> [@Learjeff](#): > > In addition, even when Xerox copiers were available, they weren’t necessarily to scale or accurate enough for blueprints. A friend who was a draftsman told me this and I didn’t believe him, so I copied a grid and held the original to the copy against the light, and sure enough, they didn’t quite match. That was mid-to-late 70’s. Things may be different in the digital world. We’re getting pretty esoteric here, but now that you brought it up… One model of Xerox machine had an intentional built-in reduction as a feature. I believe it reduced everything to 94%. The ostensible reason was to make sure everything on an office document got copied, even stuff close to the edge or with a misaligned original, and that same model had two grippers with “Xerocopy” engraved on them. When the copy was made, the engraved word was copied too – free advertising, I guess. Nevertheless, it was an idea that didn’t last long. Multiple, successive copies got smaller and grungier. Unless you are talking about one of these models, I would be a little surprised if the blueprints were more accurate to the originals than Xeroxing. All but the roll-feed Xerox models used sheet feed, and this has the potential to minimize distortion. In contrast, all Diazo machines handled the original/copy pair in a roll manner, winding both around a drum. This makes slippage likely. Indeed, when we fed a 4-page music sheet (13" x 38"), we deliberately extended the original past the edge of the copy paper about an 1/8 inch, since we knew the other end would probably slip and lose 1/8 to 1/4 of an inch overall. Of course, being 100% accurate for measurements wasn’t important to us. ---
**Author:** ![UncleFred](https://avatars.discourse-cdn.com/v4/letter/u/f0a364/32.png) [@UncleFred](https://boards.straightdope.com/u/UncleFred)\ **Post date:** [December 31, 2013, 9:02pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/50 "2013-12-31T21:02:12Z")
> [@Musicat](#): > > We’re getting pretty esoteric here, but now that you brought it up… > > One model of Xerox machine had an intentional built-in reduction as a feature. I believe it reduced everything to 94%. The ostensible reason was to make sure everything on an office document got copied, even stuff close to the edge or with a misaligned original, and that same model had two grippers with “Xerocopy” engraved on them. When the copy was made, the engraved word was copied too – free advertising, I guess. I remember hearing that the reduction in size was to thwart people from copying paper money and running it through change machines. ---
**Author:** ![FlyingDragonFan](https://avatars.discourse-cdn.com/v4/letter/f/c89c15/32.png) [@FlyingDragonFan](https://boards.straightdope.com/u/FlyingDragonFan)\ **Post date:** [December 31, 2013, 9:35pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/51 "2013-12-31T21:35:22Z")
I went to architecture school in the early 90s, and “bluelines” were pretty ubiquitous. We’d draw on 24x36 sheets of vellum with [Koh-i-noor](http://www.westnc.com/rapidograph%20technical%20pen.gif) ink pens, and then run bluelines if we needed copies. A lot of us liked to do all our final drawings, make sepia prints from them (I think we called them “sepiatones”), then color on those sepia prints with markers or colored pencils, to give them an artsy aged look for our presentations. The medium-tone background of the print let us color with both lighter and darker colors, like colored art papers. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [December 31, 2013, 11:46pm UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/52 "2013-12-31T23:46:30Z")
> [@UncleFred](#): > > I remember hearing that the reduction in size was to thwart people from copying paper money and running it through change machines. Highly unlikely in 1965 with non-color copiers, although that problem did exist later. ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [January 1, 2014, 1:03am UTC](https://boards.straightdope.com/t/were-blueprints-really-blue/677459/53 "2014-01-01T01:03:16Z")
> [@chappachula](#): > > > [@robert\_columbia](#): > > > > Imho _Liebowitz_ used blueprints as a plot device and the book would have been more or less the same had it instead used TPS reports with the new cover sheets. The real theme of the book is > > > > Humanity is unable to learn from its past and is trapped in an endless cycle of war, collapse, regrowth, and renewed war. > > WHAT? > You mean to tell me that the real theme of the book isn’t “blueprints” ? I never knew!!! I thought it was all just about the blueprints. You’re both wrong. It’s about how the Catholic Church can provide for the continuation of the Papacy, in the event of a human-species-ending nuclear war, given interstellar space travel, with sufficient advance notice to have the opportunity to choose someone who would make a good Pope from the monks at a specific monastery, convince him to accept ordination as a priest, so he can be the Abbot of the order on the new planet, and send three bishops along with him, all without him becoming wise to the scheme until it’s too late. There’s also a subtext about Baptism being unnecessary for the extra heads mutants might have, if the extra head never woke up until the main brain dies. The truly innocent (the extra head) have no need of baptism. On the contrary, they are uniquely qualified to deliver ‘last rites’. Oh, yeah, it’s also about [‘illuminated blueprints’.](http://en.wikipedia.org/wiki/Illuminated_manuscript) [Previous page](https://boards.straightdope.com/t/were-blueprints-really-blue/677459.md?page=2)