Why Blueprints are Blue

Why Blueprints are Blue


Why Blueprints are Blue Making copies of architectural drawings hasn’t
always been the easiest thing in the world to do. For the majority of human history,
the most economical solution was simply to have someone make a tracing of the original
plans. In the mid-nineteenth century, the process
abruptly became much quicker and easier thanks to famed polymath Sir John Herschel. In 1842,
Herschel invented a method to easily copy drawings using potassium ferrocyanide and
ammonium iron citrate. The exact method, called cyanotype, is performed
as follows. First, you take a drawing of the plans done on relatively translucent tracing
paper or cloth and place it on top of and attach it to paper (or sometimes linen, Mylar,
etc.) that has been previously soaked in a mixture of the aforementioned two chemicals,
then dried. Next, you expose the papers to a bright ultra-violet light source, such as
the Sun, for several minutes. The result is that the paper soaked in the
chemicals ends up turning blue as the chemicals react to the light and form a compound called
blue ferric ferrocyanide, also known as “Prussian Blue.” This wouldn’t be very helpful for making
a copy of a document except for the fact that where the light cannot penetrate the translucent
paper, namely where the drawing marks are, the coated paper remains the original color
of the paper, usually white, effectively making a nice copy. You might see a potential problem here in
that you then can’t expose the un-blued bits to any bright light source at first,
but this problem is easily solved by simply washing the chemicals off, then allowing the
paper to dry. At this point, the copy is complete. Within a few decades of the discovery of this
method of copying (as well as other blue-printing methods such as one developed by Alphonse
Louis Poitevin in 1861 using ferro-gallate), the price dropped to about one-tenth the cost
of having someone simply trace the original plans, helping the popularity of blueprints
explode. In the mid-twentieth century, copying methods
such as as diazo prints, and then later xerographic prints, finally supplanted blueprints. Much
more recently, simply sticking with digital versions of plans has become popular, with
these having the advantage of being easy to modify and distribute as needed during the
construction process. Despite the technological changes and the
fact that these plans usually aren’t on blue paper anymore, in popular vernacular
the term “blueprints” has stuck around anyways.

100 thoughts on “Why Blueprints are Blue”

  1. Huh. And here I had this strange idea that the blue on white, or blue on blue design of 'blueprints' existed to make them HARDER to copy, because apparently old photocopiers struggled with it.
    I guess that was wrong though.

  2. This is your most bullshit answer ever, I hate blueprints, I could go and make the thing, this is the most fucked up answer I've ever heard. Do you know it would be easier for me to draw your large colon than even to bother with this sheer bullshitery. I'll tell you, this man came in with this cesna aircraft. I was amazed, this was bullshit, a 5$ buck an hour man super cedded me and just put the fucking GPS in and called it a day, it was 50K$ bucks, that's so illegal, I'm so sportsman like, that was trickery.
    Now on a solid ground of property where a human requires common sense, they are loaded to the face with raw bullshit trickery.

  3. "Blueprints" haven't been blue in YEARS. Very few architects use this system anymore. Most now use digital plotting printers which just produce black and white prints on large rolls of white paper.

  4. Well, okay, but what about those blue pencils that need to be kept wet at the tip? Do they have something to do with this process here?

  5. While I love the channel. I've taken to just google searching the questions and getting them in 5 seconds rather than 2 minute movie

  6. back  in the 70s we used blueprinting in my drafting class and they really stank with ammonia its better being Xeroxed

  7. As an former engineer with over 40 years in the industry, I have never heard the term 'Blueprint' used or ever come across such a thing. I have come across blue lines on a white background in my early years but modern processes gave a black line on a white background. Secondary masters, some years ago, had brown lines on a plastic sheet. Have vivid memories of the ammonia process. I always regarded the term blueprint as used mainly in fiction books or films.

  8. Worked with an old cyanotype machine in school a couple times- the worst thing is the fumes. Being anywhere that thing while its running will leave your head spinning

  9. Thanks for this explanation. I've been in the machining industry for over 30 years. Blueprints were always black and white and usually just called "prints". I have never seen an actual "blueprint" before. When the younger guys whom I'm training ask why they're called "blueprints", I've never had an answer. Today I found out…

  10. You also have to wash the new copy to run the reaction. It won't go quickly in a solid state, but add a bunch of water and the reaction in aqueous solution goes really fast.

  11. I sort of knew this, well a little. I have an AAS in CAD and while I have never used that degree I did get to experience the craft first hand. In HS in 98 and 99 I took a CAD class or two and while most of the time we played DOOM, wanted to find duck porn and made fun of Fur Neck (I'll let you assume why) I was rather good at it. Fast forward to 2007-08 and I decided to follow up my failed attempt's at community college with a degree in Computer Aided Design. I have quite a nack for it and consider it one of the things I could have made a living out of, but am happy I didn't. I do have to say though, the contemplative state of pencil and paper was quite the experience, while using a mouse and keyboard was second nature, it wasn't as relaxing to do.

  12. Post Apocalyptic monks in the sci fi story 'A Canticle for Leibowitz' copy ancient blueprints by colouring in the blue. They are unaware of this process and ignorant of what the images are. Classic 1950s end of world book.

  13. I'm glad that at the start of every video he tells us what youtube channel we're watching incase we ever get confused

  14. I was CAD engineer for the Great American Desk Company, before it closed, and it was really neat to look at some of the older blueprints from the 50's and 60's. Everything I dealt with personally was digital(CAD=Computer Aided Design).

  15. If you have an unholy amount of patience you can even use "blueprint" papers to record a photograph with a camera (probably large format of at least 4"x5" for practicality). The sensitivity's low so the exposure time is really long. Content would as a result end up limited to static subjects…like architecture.

  16. i wonder how a like actually helps you?
    you get payed from ads (which everyone has turned off).
    and from sponsors.

  17. Why are photo copies called xeroxes? Hint: the first practical photocopier was made by Xerox. Boss to secretary "go get this xeroxed".

  18. So what happens if you try to do a copy of something already blue lined, Like a drawing of a Blue Whale 🙂 Does it come out in blue lines or black?  LOL

  19. I was hoping you would cover the blue line process as well. I still remember the stench of the ammonia tube but I can't remember exactly how it worked.

  20. When I worked in a construction estimating office, we also had "brown line" copies. First, they weren't reversed and second, they could be copied again. But they were more expensive.

  21. You forgot to mention that the chemicals for making blueprints is highly toxic and bad for the environment.

  22. Actually the source of ultraviolet light was a carbon arc. The Sun's puny output of UV would take too long. By the mid-19 century batteries were available to supply the current and voltage.

  23. I'm an architect and have never ever used the term blueprint, or heard anyone in the business talk about it.

  24. I think actual "blueprints" dates back quite a ways, either that or its unique to certain industries
    .
    I've been an engineer since the mid 80's and I've never ever seen a blue print, nor heard any anyone use the term "blueprint".
    They were always simply referred to as "drawings". If you wanted the original, you asked for the original mylar. If you wanted a copy you made a "white print". That is until large scale photocopying and then CAD systems.

  25. The oldest blueprint drawings I've ever seen are WW1 German Zeppelin construction drawings at the University of Akron. They're kept in drawing cabinets and they are in excellent condition though they are 100 years old.

  26. Wait. Wouldn't this blue print chemical copy process result in a mirrored, and thus not very useful, copy? One with reversed images and handwriting?

  27. Thanks, very interesting stuff there. Love how your videos are always questions I never think of but am curious as to the answer. This is a 'Huh, never thought about that. That's a good question' channel.

  28. I worked in reprographics many moons ago. I was going to berate you for this when I saw the image on YouTube that shows diazo prints. Decided to watch the video. You got it right.

  29. Ready to watch another colorful fact video? Then check out this video and find out why Fire Hydrant Colors Actually Mean Something:
    https://www.youtube.com/watch?v=DPrxO_u6sT8

  30. Wow, Simon… I didn’t realize this was a father and son enterprise… so good to see Simon Jr taking after The Old Man…

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