Trimethyl Borate Lantern Built From Garbage


This lantern was built from recyclable goods. It’s a bit dangerous when used like the image above, but [The Green Gentleman] does give you a few other options in his build instructions which make for much safer operation.

The lantern enclosure is made from old cans and a glass jar. He screwed a couple of boards together at a right angle to act as a jig for cutting the glass. The V-shape created by the boards holds the jar on its side, giving his glass cutting tool something to rest upon. He then turns the jar to score it around the top, and then bottom. He alternated pouring boiling and chilled water on the score mark to shock the glass into breaking along the line.

This makes up the clear part of the enclosure which is later mated with metal top and bottom pieces. From there he adds either an LED, an alcohol lamp, or the Trimethyl Borate lamp seen above. The first two are relatively safe, but the latter burns at around 1500 degrees F. We have reservations about using a plain old glass jar as the enclosure for something burning this hot. It really should be heat resistant glass.

18 thoughts on “Trimethyl Borate Lantern Built From Garbage

  1. Borate-based roach killer (usu. boric acid) dissolved in ethanol (mostly colorless flame) will produce a green flame at a safer temp. Easier to come by than trimethyl borate. The fumes aren’t toxic, but I wouldn’t want to be trapped in a closet with that as my only light source. The same boric acid would probably work with some oils, the problem is, the oils themselves burn yellow and don’t dissolve boric acid readily.

    1. I’ve done this with the bug killer as well – and as the instructible says methanol works best.

      If EtOH is used the flame is less blue, and you make triETHYLborate. I personally tested with 75% EtOH (151 rum) and noticed a less spectacular green effect. Everclear may work better.

      Oils won’t work, because the chemistry isn’t there – boric acid has to undergo a chemical change to easily burn with a green flame. Check wikipedia for more info (it’s fascinating)

      I do worry about the methanol released from these sort of candles. Chemically, if you get a complete burn there should be nothing but H2O and CO2 and a little B2O3. I’d still worry about inhaling vaporized methanol – especially after blowing out the flame.

      The summary makes it sound like he’s burning pure trimethyl borate. He states how he gets the effect in the article, and it’s most certainly not pure trimethyl borate. Also, methanol will burn at 1500 degrees (according to the article, didn’t verify that), regardless of there being boric acid in the mixture. It may be possible to produce extremely small amounts of more pure trimethyl borate by distiling the methanol/boric acid mixture (64C VS 68C), but I’d say it’d be very hard – and it’s not what he’s doing.

      That said, this is a very fun experiment to do. Give it a shot if you can.

    2. Trimethyl Borate is the standard boric acid added to methanol. very similar and just as easy to get “parts” and to produce. Stir in Boric Acid until the solution will not disolve any more, filter, and done.

  2. Never thought about this till now- but in watchmaking school, we use boric acid mixed with denatured alcohol until it is a paste in consistency to waffle batter, then coat steel parts with it, and light in on fire as a preparatory step for heat treatment. This is done of course with the part in a wire steel basket.

    The alcohol burns off, leaving a coating of boric acid to protect the part from fire scale during hardening afterward, but the flame of the alcohol burning off is bright green!
    Could denatured alcohol be used for this with boric acid mixed in instead?

    1. Denatured alcohol and Boric acid is actually used by some fire-jugglers as a way of making a bright green flame, so I don’t see a reason why it can’t be used in this amazing build

      1. Fire jugglers do it with methanol, at least everyone I’ve ever known and I’ve been at it for a dozen years. It should also work with denatured/ethanol, but in my experience is not as bright green as with methanol. Of course methanol is cheaper and much more readily available in my neck of the woods so that would definitely factor in to what people choose to burn.

        Personally I’m not so fond of it myself, though I’ve done countless shows with it in the past. The fumes get to be a bit stinky for my taste and it’s not very bright. Give me straight up camp fuel (white gas/naptha) any day.

    2. “Could denatured alcohol be used for this with boric acid mixed in instead?”

      Yes – as Mad Causal had pointed out before you asked. Denatured alcohol is simply adulterated ethanol; typically 90% ethanol and 10% methanol. Many other denaturing agents can be used – the only real criteria is that it’s made unsuitable for human consumption (and preferably difficult to purify via distillation or other simple techniques).

  3. The question I have is: How healthy is it to breathe whatever chemicals are found in the combustion products of this solution??? The methanol is much less a concern when burning as it does under normal circumstances burn quite clean on it’s own….. But the borate product??? This solution of boric acid in methanol as is commonly used by jugglers burns without leaving a residue, which means that the boric acid is forming some type of volatile combustion product. What is it, and how healthy or not is this stuff????

  4. Ethanol/methanol can be gelled with calcium acetate (antacids+vinegar+free time). I know in the tutorial the alcohol is in a lidded container so there is little risk of a spill and subsequent fire, but at least in a gel state the risk is more contained. I wonder if a small amount of boric acid could be added before forming the gel. I know what I will be doing later!

  5. Alluring as it looks I also would have reservations about having a live flame enclosed in glass not designed for the purpose. Having said that, jam jars are okay with heat. You can sterilize them by putting them in a hot oven for a few minutes.

    An alternative could be to use a hyperbright LED, or a cluster of them. These have the advantage of being highly energy-efficient.

  6. Hi,

    I’m the author of the Instructable featured here. First of all – thank you for the props! I love this site, and I’m totally geeked to be on it!

    Secondly, I’m aware of the concerns expressed here about flame temperature, and I’ve tried to address them in a new paragraph in the first section of the Instructable. I’ve clarified that the 1500 F temperature is at the inner cone of a methanol flame using a much larger wick. The metal top of the lantern doesn’t get anywhere near that hot – if it did, the wood knob on top would char, and it doesn’t. The glass is even cooler than the metal lantern top. I’ll try to find out how hot the glass gets, but I suspect it’s enough to boil water and not much more. As relates to the trimethyl borate, spector306 is quite correct that not very much is created in this reaction. I touched on that in the earlier instructable I linked to this one, but did not reiterate. I’ll try to fix that too.

    Thanks, everyone for reading!


Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.