Cool gadgets you never heard about: alcohol blowtorches.

The goal of the blog is to show you new stuff you might have never seen before.
Apart from hobbies and projects, I will also sprinkle articles about low profile cool devices or technologies here and there.

My pick of the day is alcohol blowtorches. They date from somewhere between the time when the ominous flea market petrol blowtorches were a thing, and before everybody got cheap and easily accessible compressed propane.

Precise hot flame, no moving parts, from a fuel you can make at home even after the zombie apocalypse.

They're very elegant in construction and simplicity, and produce a nice roaring pressurized hot flame, using only alcohol as a fuel source.
They're suitable for a variety of jobs, including soldering, or scavenging electronics parts.

Operation

Those torches operate on the self pressurized fuel vapour principle.
What this means, is the heat from the torch itself, gently vaporizes the liquid fuel.
Vapours build up inside the device, and get lightly pressurized, just enough to produce a nice precise roaring flame at the small output nozzle.

A simple example of a device that both shoots fire and heats itself up at the same time.

This is the simple and elegant operation principle that also drives alchool/penny stoves (about which we will also talk in an upcoming short-project article).
And it is opposed to other styles of pressurised torches, where you have to pump additional pressure in, making fore more complex and failure prone designs.

It works mostly like the petrol blow torches you probably already know about.

A common design of petrol blowtorch.

But how does that elegant and simple design work anyway ?
Let's take the case of the iconic Lenk alcohol blowtorch design.
The lamp is made of two tubes, held together with an articulated joint.

The iconic Lenk design. One among lots of variations on the same operation.

The highest tube, mostly works as an alcohol lamp/candle. It is nothing more than a reservoir, filled with alcohol, topped by a large wick/pad.
It is lit on fire, and heats the other tube nozzle.

The nozzle tube extends down into the shortest tube, which is also filled with alcohol.
Heat transfers from the tube to the fuel, which in turn evaporates and rushes out of the nozzle, producing the useable flame, while also feeding the "pilot" flame to prevent blowouts.
An additional wick running down the tube helps bringing more fuel in contact with the warm metal and enhances vaporisation.
The pressure build-up ensures a "jet" flame, as opposed to a free burning one, like that of an oil lamp.

Cross section of the torch.No moving parts. Only metal reservoirs and cotton wicks.

If you're interested, the original patent can be found here.

DIY and variations

Those torches are now easily available on ebay. But you can also make working tools on the same principle as quick projects.

Making actual clones would require more work, but is still possible in the home workshop.

This Make article is about making an alcohol lamp, that could become one of those torches with just a bit more work.

The Internet has many occurrences of "DIY alcohol blowtorches".
Many of them just random useless Youtube projects using fireas an excuse, some of them actually useable designs cloning other kinds of commercially made torches. Finally, some of them are clever proper tools made from scarce materials, and features in old time DIY magazines, from an era where resources were scarce and tools expensive.

This one mimics a common commercial dental work torch, it isn't self pressurising but rather uses squeezes on a plastic bottle to produce intermittent fire spikes:

The commercial version

Great depression era article on how to make a very simple yet effective fixed torch for the shop.

There are also multiple commercial variations around the design, including varying flame configurations, or solder iron extensions:

The reason I like those is the ingenuity in their design.They're both simple and effective, and make for a very good ratio of manufacturing effort vs usability.

There is no parts to wear or break (seals, valves, threads...), and that the fuel itself is always guaranteed to be available, even in the most remote country or rural area, or after the beginning of the zombie apocalypse. (I'll make some posts on brewing and distillation in upcoming articles too.). Pressurized butane or propane isn't even available in some countries right now, and petrol derivatives are of unknown future, or can't be produced outside of a working oil industry. 

The vintage touch, and the discovery of "how it was done before our fancy tech" also greatly contribute to how attractive those are. 

I will make more posts of that essence, to highlight a few lost technologies or mechanisms, that were used while we were still trying to figure out the best way to do things.

Those will deal with powerless water pumps, locks and restraints history, alternative fuels and energy conversion and storage, or even electricity-less ice making. 

The past is full of ingenuity, and many objects we take now for granted are the results (or just another step !) of a long refinement process.

I hope you're interested in those things too.

If not, don't worry! Cool and niche hobbies and projects are also coming!