Soldering Like It’s 205 BC

Did you ever stop to think how unlikely the discovery of soldering is? It’s hard to imagine what sequence of events led to it; after all, metals heated to just the right temperature while applying an alloy of lead and tin in the right proportions in the presence of a proper fluxing agent doesn’t seem like something that would happen by accident.

Luckily, [Chris] at Clickspring is currently in the business of recreating the tools and technologies that would have been used in ancient times, and he’s made a wonderful video on precision soft soldering the old-fashioned way. The video below is part of a side series he’s been working on while he builds a replica of the Antikythera mechanism, that curious analog astronomical computer of antiquity. Many parts in the mechanism were soldered, and [Chris] explores plausible methods using tools and materials known to have been available at the time the mechanism was constructed (reported by different historians as any time between 205 BC and 70 BC or so). His irons are forged copper blocks, his heat source is a charcoal fire, and his solder is a 60:40 mix of lead and tin, just as we use today. He vividly demonstrates how important both surface prep and flux are, and shows both active and passive fluxes. He settled on rosin for the final joints, which turned out silky smooth and perfect; we suspect it took quite a bit of practice to get the technique down, but as always, [Chris] makes it look easy.

If you’d like to dig a bit deeper into modern techniques, we’ve covered the physics of solder and fluxes in some depth. And if you need more of those sweet, sweet Clickspring videos, we’ve got you covered there as well.

42 thoughts on “Soldering Like It’s 205 BC

        1. I live down aquifer from a super fund site.

          The cities well water is contaminated with a number of industrial chemicals (and lots of lead), as part of the settlement the federal government covers all the costs of treating our water for those things.

          a couple of years back a new chemical (industrial solvent) was found in our water, while they are getting the equipment installed for the new system our wells were shut down, and our water source was pumped in from a nearby large city, they used treated surface water.

          The PH of the new water source was corrected and matched that of the old water source, the water ended up being a bit warmer (surface water) out of the pipes, and the water from the other city was not as hard as the water from our wells.

          The end result was non-acidic water leaching lead from pipes that were not leaching lead with the previous water source.

          So no, it doesn’t require acidic water for lead to get into the water supply from lead solder… all it requires is a change in the water, it could be temperature, it could be level of calcium in the water, it could be any number of things, so the question has to be, why risk it when unleaded solder works just as well?

          1. For (Copper) pipes for potable water leadfree solder is a good choice. For electronics – which are not intended to be ingested – it is a very poor choice. It decreases product reliability and lifetime.

          2. I dunno if it was PEX fitting, it was a “shark” push on union, label on said ” California has determined that the chemicals contained causes cancer”. I returned them

          3. Everything causes cancer in California. The law, written by the people, not the legislature, requires listing of everything that is even suspected of causing cancer without regard to quantity. Parking decks have warning signs that say “This area may contain exhaust emissions which are known to the state of California to cause cancer”.

    1. I generally feel the same way about lead-free solder, but you have to think about what you’re doing. When I built freezer alarms and other devices that are used near food, I was very happy that lead free solder is so easy to come by these days.

      So yeah, 95% of the time I’ll used leaded solder until they pry it from my cold dead hands but RoHS solder has a place too.

  1. I don’t see the discovery of soldering that difficult. Copper, tin and lead were some of the first metals men used. So I am sure at least when experimenting with alloys like bronze, soldering could have been discovered easily. The melting point of the components is very different, and also the addition of flux like substances is somehow natural when experimenting with metallurgy.

    1. Possibly the discovery for processes could’ve been someone drinking and throwing things into a fire then waking up and finding the conglomerations of metals melted overnight, or someone that was a smith / tinkerer seen the result and asked how that drunk did it or it was a drunken tinkerer etc possibilities, It’s all very depressing

    1. An Iron is something that has come to be a universal term for something that applies heat. Things like branding irons and clothes irons would have been made of iron, today however they can be made of a variety of metals.

      It is the same way we use terms like ‘record’ for a music track or in British english ‘Film’ for a movie despite records and film mostly no longer being used to record music and movies.

        1. A cord means a ligature, a bind, and a rib-like texture of fabric, which also reminds of rows of text in a book, and the joining of letters as in cursive handwriting. What medieval monks were scribbling onto books were “records”, and that was the original use of the word.

          Now that any kind of data is handled digitally, in strings of binary digits, the word “record” has the same meaning as to “file” (“to arrange in order”), and it’s perfectly meaningful in the sense of recording music.

    2. Eons ago when I was in junior high, they *were* called soldering coppers, at least by my metal shop teachers. Possibly to distinguish them from the electric soldering irons we also used.

  2. You think soldering is unlikely? Wow. It’s incredibly obvious. Heat a low melting point easily obtainable metal like tin or lead and use it to tack other metals together.

    You want to talk about unlikely. How was bread ever invented? Or coffee….take the seeds of certain inedible cherries, semi-burn them, grind them into a powder, and steep that gunk in boiling water. Who would have ever dreamed that up?

    1. People have probably always wondered what happens when you mix different things together. Lead + tin = solder. Experiment with ratios. Same goes for brass, pewter, semiconductors, battery electrolytes and plates… and some of the combinations of materials in those latter two boggles the mind as to “what on earth made you try that!”

  3. Soldering irons like the ones used here were in use as late as the 1800’s I have a tool chest made by my great-great-grandfather, with many of the original tools. There are 2 soldering irons that are basically lumps of copper on a handle. Years ago, I used them (I use the woodworking tools to this day). They work surprisingly well, it was a *very* mature technology by then…

  4. Could also have been done without an iron, either by “chip soldering” or coating one side of the smaller parts with solder, positioning the parts, and heating in an oven, much like SMT today. (Chip soldering = cut a small chip of solder, place next to the joint, heat.)

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