DIY Conductive Glass You Could Actually Make

Transparent, conductive glass is cool stuff and enables LCD panels and more. But the commercial method involves sputtering indium-tin oxide, which means a high vacuum and some high voltages, which is doable, but not exactly hacker-friendly. [Simplifier] has documented an alternative procedure that uses nothing more than a camp-stove hotplate and an airbrush. And some chemistry.

Make no mistake, this is definitely do-it-outside chemistry. The mixture that [Simplifier] has settled on includes stannous (tin) chloride and ammonium bifluoride in solution. This is sprayed uniformly onto the heated glass (350-400° C), and after it’s evaporated there is a thin, strong, and transparent layer of fluorine-doped tin oxide. [Simplifier] reports resistances down in the single-digit Ohms per square, which is pretty awesome. [Simplifier] didn’t get the mix down perfectly on the first pass, of course, so it’s also interesting to read up on the intermediate steps.

Our thoughts immediately spring to masking sections of glass off and building DIY transparent circuits and panels, but we suspect that we’re getting ahead of ourselves. Still, this is an incredible early result, and we hope that it opens up the way to crazy transparent-conductive applications. What would you do if you could make glass circuits? Well, now you can, and it doesn’t look too hard.

58 thoughts on “DIY Conductive Glass You Could Actually Make

  1. “reports resistances down in the single-digit Ohms per square”
    ? per square what ? please, HaD “authors”, do you job, and verify what you write. The units are inches. Ohms per square INCH.

    1. Found this online, article by Thomas Pratt; might help:

      *”When first presented with the units of ohms per square, many
      students either think it is a typographical error or ask the question “Ohms
      per square what?” But after a moments reflection about how surface
      conductivity is determined, then the units make sense. A square of material
      is selected, if a small square is used, the electrodes are short and close
      together; if a large square is used, the electrodes are longer but further
      apart. In both cases the resistance is the same, thus the units of “ohms per
      square”. Obviously, a determination of Lambda is not made with a configuration
      of electrodes…since there would be all sorts of edge
      effects. The determination is made with electrodes which are concentric
      circles and Lambda is derived from the geometry.”

  2. If you can control which areas become conductive and which don’t, or would consider security glass. Mask the conductive line into a zigzag that doesn’t cross or use multiple lines across it. Glass breaks, circuit is broken, alarm goes off.

    1. In practice you wouldn’t even need a dense zig-zag pattern. A line every couple inches will suffice, and a Hilbert spiral would probably be more secure.

      I’m wondering how much current this coating can take. It would be great for transparent heating elements in windshields.

        1. I don’t know about ITO deposited using this method, but traditionally manufactured ITO coatings are routinely used for heating LCDs for use in cold environments (where the LCD would normally fail to operate).

          I don’t know if you could use it for heating to temperatures that high – ITO coatings are GREAT for preventing freezing though.

        2. But why? No reason for a print bed to be clear. The only reason people use glass at all is for the smooth surface.

          Me, I’m chicken. I’ll stick to an aluminum plate until my print head stops crashing into the build plate.

          1. I print on a mirror…it is optically flat and thick enough not to follow and uneven areas of the aluminum bed. Same as printing on glass, because I am, with the added benefit of being able to see the nozzle in the reflection in case of any unwanted filament disbursements. It works very well.

      1. Heated windshields get my vote for an application for this. The beauty thing is immediate defrosting action without the cabin having to be approx room temp. I bet luxury cars would have this first.

        1. Heated windshields/windscreens already exist but they do it by an embedded wire (similar to the often used one on rear windows but with significantly finer wire) but suffer from the wire reflecting any sun – this does have the benefit of being uniform (albeit with a slight discolorisation).

          I wonder if the speed (of defrosting) or durability is the reason why it is not currently used?

  3. “resistances down in the single-digit Ohms per square” -> per square WHAT ? bananas? apples?

    It would be nice if the “authors” check if what they copy-paste makes sense, prior to posting. Deceiving HaD…
    From the original article it´s about inches. Ohms per squares inch.

    Also, no mention of the toxicity of the chemicals used, instead it is “hacker-friendly”. A bit irresponsible, no ?

      1. Haha! Brian 1 : HAD readers 0
        It looked so much like a typo I assumed it was wrong, but As soon as you said it was correct, I could see that’d make sense, though it’s counter-intuitive.
        Slightly surprised it didn’t warrant a note in the article, or did you leave it out just to troll us? :) very well done!

      1. I don’t know why more people aren’t making a big deal of this and choose to attack the ohms/sq. Ammonium bifluoride mixed with water makes hydraflouric acid at roughly 1/3 the concentration of ammonium bifluoride. HF…is nasty…..really nasty…..I mean really really nasty. Those who work with strong acids on a regular basis often refuse to work with HF. Its burns are said to be painless (well, they create a painkilling effect), the acid is absorbed through the skin where it seeks out calcium, goes straight for your bones. Amputation is a common method of treating HF burns. It can be handled safely, and at low concentrations can be prevented from hitting your bones, but you absolutely need calcium gluconate on hand, and lots of it. You should also plan on spending the rest of the day in the ER should you spill some on yourself. You should plan on wearing a respirator as well as gloves. (fumes are just as toxic).

        Seriously, don’t mess with this stuff if you don’t do a lot of study beforehand. Talk to those who do handle the stuff for a living. Look up the gruesome stories. The SDS/MSDS these days make everything sound like it is about to kill you (I mean look up the one for dihydrogen monoxide :) ) so the SDS/MSDS for HF doesn’t seem too bad. Notice the one main difference, it says to seek medical help for any exposure. There’s a good reason that’s added on there. Also note the specific mention of calcium gluconate, and not just any base to neutralize the acid. You have to draw as much of HF to the calcium as possible before getting to the ER. Seriously seriously nasty stuff.

        1. Hydrofluoric acid is nasty, sure. But don’t try to make it seem worse than it already is. Hobbyists do use and have used a lot of very dangerous chemicals, HF, cyanides, misc. carcinogens etc.

          1. Yeah but it really is that bad. I use it in a stripping bath to remove powder coating, B17 for those curious. It’s only 1-5% according to the SDS, but that is enough to INSTANTLY cause a deep chemical burn; literally so quickly that you can’t rinse it off before you get a burn.

            I’ve also seen a mixture of HF and nitric acid eat up a pair of “acid resistant” gloves in a matter of seconds, also causing some nasty burns.

            It is that bad and is no joke, that being said as long as you take the proper safety measures it is safe-ish.

        2. It’s not that bad in the concentrations I used for this project. Each 30mL batch has as much fluoride as a tube of toothpaste, roughly. I’ve gotten it on my hands and nothing bad happened. Gloves and goggles are a good idea for sure, but it’s not like it’ll dissolve your bones if you make a mistake.

          1. I’m sure you are familiar with what you are using… My response was only to Megol’s cavalier attitude about HF. When you’re making it in situ and in small amounts it’s totally controllable.

            I’ve also heard that sufficient exposure could cause a heart attack as it soaks the calcium out of your blood, but that could be a myth…

          2. I’ve been wondering about the minimum concentration of HF to cause problems. Lithium Ion Batteries use Lithium Hexafluorophosphate as the electrolyte and I’ve wondered what is the best and safest way to neutralize it as it makes HF when it contacts water. The only thing I could think of was to drop it in a solution of calcium hydroxide as that should precipitate it out as calcium fluoride. But this stuff makes me too nervous to even try.

        3. Agreed. HF is EXTREMELY DANGEROUS. Do not get near it before talking to a chemist. I worked with it in my thesis work and had to develop a set of security precautions to avoid loosing my health. Even breathing dispersed fumes can burn your lungs or eyes and it is VERY EASY TO MAKE A MISTAKE. Do you trust wannabe chemists. HF can destroy glass.

          1. When I was a kid, I deal with HF (work with glass itching and in chem lab experiments) burn hands a lot. 40 years gone and my hands still not amputated and I am alive :-). Just standard lab safety procedures like with all strong concentrated acids, sulfuric acid , Nitric acid all of them. Nothing incredible terrific.

  4. Anyone have a good etching chemical for tin. I started looking, but I thought I would comment as well.

    Without a good etching chemical this is useless to me. With a good etching chemical I will be making a see though HUD

  5. I wish there was DIY way to make solid state window shading coat. Something that you spray on window that you then would be able turn between black (or at least opaque) and transparent using electricity. There are some commercial solutions, but they are expensive AF.

  6. “Make no mistake, this is definitely do-it-outside chemistry. The mixture that [Simplifier] has settled on includes stannous (tin) chloride and ammonium bifluoride in solution.”

    Ahhhh, the 1950’s mindset that it’s okay to spew toxic crap into the air / dump it in the ground / into a river. Out of sight? Harmless / not my problem!

    1. And where do you think it goes if you do it inside under a fume hood? The biggest reason to do this outside is so that you can reduce concentration of fumes/spills easily, not just to dump it outside.

    2. I specifically designed the formula to be environmentally benign, since I was doing this in my backyard. Any solution that hits the ground (whether it’s dirt or concrete) will instantly precipitate tin hydroxide and calcium fluoride, both of which are harmless. The fumes are acidic, sure, but it’s no more harmful than using muriatic acid to clean concrete. The minute amount of HF that gets released can be safely disregarded on anything less than an industrial scale. I think I’ve used less than a gram total of ammonium bifluoride throughout this whole experimentation process.

  7. spraying tin chloride solution on hot glass is called fuming, and is a very old craft technique for people doing decorative glass work. Many other chemicals have been added, I’ve read that there are hundreds of French patents on this subject from around the turn of the 20th century. The chemistry will determine what forms and thickness the metal film up: metalic, oxidized, some combination.
    A gold or silver wire in a torch flame can also be used to deposit metal films on glass. Look on YouTube, there are several videos.
    Keep in mind that hot glass can be quite chemically reactive. Some glasses slowly dissolve platinum crucibles, a major problem in laser glass. Tin shouldn’t be a problem at all….

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