Just a friendly reminder that most common types of thermal paper contain BPA or BPS. You really should be avoiding these endocrine disruptors when possible.
“Most common types of thermal paper contain BPA or BPS” That's not valid everywhere.
The European Union decided in 2016 to forbid the use of BPA in thermal paper. [1] BPA is currently still used but will be completely banned in 2020. And, even if BPS will be allowed, EU surveys seem to show that alternatives to BPA/BPS are being considered for thermal paper.
I mean, good for them, but if BPA is "still currently used" and alternatives to BPS are only "being considered", then in the EU both BPA and BPS are still in thermal paper right now, yes?
So, in fact, it is valid to say that "most common types of thermal paper contain BPA and BPS."
If someone did a HN post on their awesome tritium-faced retro clock project, I would hope someone would be there to educate the younger readers about the history of that material as well.
If you really think I was shitting on the project, my apologies. I prefaced the sentence with "friendly reminder" as in "hey, perhaps this is something you should know about your materials, just like working with tritium".
And, at the end of the day, I didn't upvote myself this far. So ¯\_(ツ)_/¯.
it's a blessing and a curse.... when solving bugs it helps to have lots of different pairs of eyes on it. it's a natural tendency of people to want to warn others about a danger they've experienced.
but yeah, sometimes that does turn into a kind of contest where someone tries hard to find the detail that will mark them as an expert. That can be very tiring. If people try too hard, it shows and makes others tired.
Very cool. I made a Pi thermal printer photobooth almost exactly two years ago that worked on the same principle, although I wasn't crazy enough to try and cram it into a Polaroid shell. What seemed like a simple exercise turned into more research than what I thought I had tolerance for on a side project. IIRC from my experience there were two big problems: 1. versions matter when it comes to printer drivers, OS, and your hardware combo, and 2. the data buffer on thermal printers is not big enough for what you want to do (which is why it spits out random chars and symbols instead of your photo). The printer I was using had a buffer pin but ultimately I was short on time and patience so I opted instead to use imagemagick to convert and compress the photo before sending it to the printer. I used the booth for my nephew's birthday party and it survived real world use pretty well. You got a nice physical souvenir (I also added a "Happy Birthday" + date overlay to each image) and I set up a local server on the Pi that let people browse the digital versions of all the photos with a framework called Sigal. Very fun hardware project and I intended to publish a writeup outlining all the sharp corners I navigated but never got around to it.
> Long before the final assembly I'd wired the little LED under the viewfinder to one of the pi's GPIO. I'm not sure what it originally represented...
From the manual[1, 2]:
When you are not using flash, a red light may appear under the viewfinder as you begin to press the shutter button. It warns that the lighting on the scene is not bright enough for picture taking without a tripod or other firm support.
Also, this bit from the manual is somewhat amusing given the extraordinary chain of events occurring inside the hacked camera:
As you begin to press the shutter button, your camera releases sound waves to the central part of the scene. The frequencies are far beyond our range of hearing and travel at the speed of sound. The split second it takes for the sound to reach your subject and the echo to return is fed into a tiny electronic computer inside the camera. The computer uses this time measurement to calculate the distance between the camera lens and your subject, then signals a motor to turn the lens until your subject is in sharp focus. This extraordinary chain of events takes place in less than 1/3 of a second.
Makes for a much more in-depth and capable version of the Game Boy Camera + Printer: https://en.wikipedia.org/wiki/Game_Boy_Camera an object of gadget lust for me when I was growing up
I had the camera as a kid. Ben Heck did some interesting reverse engineering on the printer, and there's some stuff on Hackaday too if you're interested.
I built pretty much exactly the same thing, but without the polaroid camera shell, but did not get around to writing about it. A couple suggestions:
1) Apply exposure compensation and dithering to the image. this allows a better fidelity output. Example: [https://i.imgur.com/eCLRs8Q.jpg] you'll have to play around with the exposure depending on the camera you're using.
2) the 3" paper printer would make for a much better output than the 2" one, simple because the former is closer to an actual photo size.
With time running out and no better option in mind, I broke out the cutting disks and surgically removed one of the USB hub circuits from the 7-port hub."
Regarding his earlier rant about USB hub quality, I have to agree. It's getting harder to come by a robust USB hub nowadays. Bad connector and power supply quality (USB hub PSUs are electrically noisy and way under powered for the number of ports).
Why I love Hacker News. I read an article about a cool hobbyist project, and my mind leaps to someone at work was having trouble with a thermal printer... and I just realised what the fix for their problem is...a total tangent but that often happens.
I kinda like the concept, too. Beyond just the whole execution, which is really well done. Thermal paper disappears over time. So this in turn means these photos are somewhat ephemeral. I haven't lived long enough to know whether I prefer photos or pure memory, but I have to assume there's something redeeming about relying solely on your memory.
But I also love that my children one day will be able to see perfectly accurate photos of myself in my 20s, whereas photos of my parents + their parents have considerable wear.
At an old temp job I had, my manager, much older than me, habitually photocopied faxes as they were received precisely because the thermal paper fades over time. Even stored well, in the dark, in a dry box, they'll gradually fade over time. Leaving them exposed to the light will fade them really quickly.
I think you would need to scan the images and have them printed onto proper photo paper if you wanted to keep them. Keeping them in the dark slows the fading process, but that is all
Just an FYI regarding thermal paper and highlighter pens.
At a former job some of the staff were printing some free product vouchers. On each they highlighted certain data to make it easy to spot. Well they soon found out that a highlighter on thermal paper will erase what is highlighted. It takes some time but it does a great job of erasing it. I don't know how or what the chemical process is but it does work, or fail, whatever your goal was I guess.
Well, with the right chemistry you could expose an image directly onto a piece of paper and embed the exposure fixing chemicals on the edge such that a roller would automatically apply them to the paper...
Does thermal paper darken if left in the sun? If not, I don't see how a projected image will be hot enough to burn an image. Even if it warms up the paper, the process has to happen fast enough that the heat isn't conducted to the surrounded area first. Maybe you could make a solargraph with thermal paper, where the sun burns a path over many days.
Typical photographic paper (developed in the darkroom) or direct positive paper is better suited to what you're suggesting.
Of course it does exist.
It’s a “light amplification by stimulated emission of radiation” device better known as laser.
Although it can’t be used to amplify the light field in its entirety.
I know about lasers. I meant the entire waveform. Vacuum tubes do that for electricity. It seems the only similar method is to use a lens, a smaller sensor, and hopefully the initial light is bright enough so when it's miniaturized, it does the chemical/electrical work necessary on the film or sensor. Film negatives already uses this concept - taking ordinary light and increasing its power by minifying it over a smaller surface area.
A laser can amplify only a very specific frequency and it will lose all the color information.
At that point it won’t be analog light amplification given that the output light won’t have any of the characteristics of the input.
Also, for those unaware, people at Polaroid thought so, too, and released a thermal-printing color Polaroid SNAP a few years ago. It makes prints comparable to Fuji Instax, but the camera is digital and pocketable.
I've owned it for a couple of years, and I call it the friend-maker camera.
He says in the video you can’t buy one but I recently bought a Polaroid camera as a gift at Urban Outfitters for $100, plus the expensive film ($30 for 8 shots) that goes with it. Is this different in some way?
Polaroid themselves stopped making the cameras and film. "Polaroid Originals" is a Dutch company that bought Polaroid's instant camera brand and IP. They were previously trying to re-create Polaroid instant film on their own, I think (or they'd bought one of Polaroid's film factories, or something?)
Anyhow, I think they're the ones producing film now, refurbishing old Polaroid cameras, and also selling their own model.
Polaroid Originals were originally called 'The Impossible Project' and was a kickstarter campaign based around recreating the original Polaroid Instant film.
It ended up being so successful, that they managed to acquire the brand name and IP of Polaroids Instant Camera technology.
They didn't buy the IP for the chemistry for the original Polaroid film though, as Polaroid sold that to Fuji.
That's why there's only 8 instead of 10 photos in a pack, because their chemistry required thicker photos, and the photos take about 30 minutes to self-develop, rather than 30 seconds of original Polaroids or Fuji Instax.
https://www.pca.state.mn.us/green-chemistry/bpa-thermal-pape...