Letter Re: Post-TEOTWAWKI Welding

James Wesley;
I’m worried about keeping farm machinery operating, in a long-term TEOTWAWKI whammy. Some of my equipment is horse-drawn and a full century old. God forbid we go through a multi-generational scenario like you’ve talked about. How will we repair broken metal, or cast metal, or join metal (‘cept drilling and nuts and bolts)? Obviously arc welding is out, unless someone has a huge solar battery bank, and I’m not at that Pay Grade. (I live almost paycheck to paycheck, other than a seasonal bump when I sell hay each year.) And gas welding will be non-functional once the available welding gas supplies run out. I also saw the SurvivalBlog piece on the giant fresnel lens solar oven (for aluminum casting) but beyond that I’m stumped. What am I missing? Thanks for your time, – Rod C.

JWR Replies: Missing? In a word: Thermite. (The formerly patented trade name was “Thermit.”) Thermite welding is a simple process that just employs a mixture of iron oxide powder and aluminum powder to create what my high school teacher called “a vigorous exothermic reaction.” It is most commonly used to join railroad tracks, using specialized molds and tooling. (Thermited tracks don’t have that traditional “clickety-clack” sound.) The only fairly exotic material needed is magnesium ribbon, to ignite the mixture. An Aside: My #1 Son found that a Blast Match or Sparkie fire starter (both sold by several of our advertisers) works just fine as an igniter, just by itself.

The iron oxide and aluminum powders needed for thermite welding can even be produced locally, albeit very laboriously, with materials from your local automobile wrecking yard. (Hint: Look for aluminum “Mag” wheels.) Welding with thermite can be tricky: If you use too little or if you don’t contain the “puddle” properly, then you don’t get a good weld. If you use too much, then you destroy the parent metal. Practice a lot now with scrap metal so that you don’t make costly mistakes, later.

Warning! All the usual safety provisos for welding apply, and then some! Thermite burns at thousands of degrees and looking directly at the reaction can cause permanently-blinding retinal burns. You’ll need welding goggles. Since a thermite reaction creates its own oxygen, unless you have a Class D fire extinguisher there is basically no effective way to fight a thermite fire. (Without a Class D extinguisher you have to just wait until it burns out–although cooling it with a CO2 extinguisher helps a bit.) Also, keep in mind that if a glob of burning thermite contacts water or even just mud, it can cause an instantaneous steam explosion that will throw burning thermite in all directions. Also, using finely-ground thermite powder, or any sort of expanding gas containment can also cause thermite explosions, so use extreme caution. And if you aren’t wearing welding clothes and dark welding goggles when igniting thermite, then you are foolish. After mixing or otherwise handling loose thermite powder be sure to thoroughly wash your hands before using it. (Setting your thermite-powdered hands on fire would be a Very Bad Thing.)

Thermite has many other clever uses, as described, in my novel Patriots. (The Mythbusters guys demonstrate overkill.)

Reprints of two old thermite welding references now that are now in the public domain are available from Amazon.com. They are:

Thermit Welding Process 1914 by Richard N. Hart


Thermit Welding (A series of articles revealing the art and science of welding) by Ethan Vial

Thermite welding is also briefly described in the free Kindle e-book: Oxy-Acetylene Welding and Cutting Electric, Forge and Thermit Welding together with related methods and materials used in metal working and the oxygen process, by Harold P. Manly.

An inexpensive source for iron oxide powder, aluminum powder, and magnesium ribbon with excellent customer service is AlphaChemicals.com. They have been a SurvivalBlog advertiser since early 2011, and I must mention that I have had ZERO complaints about the company, since then. They have satisfied thousands of SurvivalBlog-reader customers. AlphaChem now packages most of their iron oxide powder and aluminum powder in resealable heavy duty mylar pouches. This keeps everything neat and dry. They double package and discreetly ship via UPS in boxes that just have one small blue “ORM-D” safety label. (The binary components are not classified as pyrotechnics until after you mix the component powders yourself.)

Because of its weight, any casting equipment (molds, crucibles, refiner’s sand, etc.) is best found locally, from an industrial supply company, or better yet used, via Craigslist. And of course terra cotta clay pots are available at garage sales or your local garden supply store.

Lastly, keep in mind that if you are planning to cast metal with Thermite, then wet sand or damp clay processes cannot be used. (See my previous warning about instantaneous steam explosions.) Your molds must be quite dry!

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