I’d been a blacksmith (mostly in a hobbyist capacity) for nearly decade when in 1998 this passion combined with my historical interests. As a result, my wife and I founded the reenactment group Ancient Celtic Clans.
Now, one of the advantages ACC has is that Sarah and I are both blacksmiths. This is key because almost without exception every other Celtic skill, either directly or indirectly, needs a blacksmith to make tools for them. It also means that we can recreate all the period correct tools we might need when learning any other new skill. This core dependence on the blacksmith was just as true back in 300BC as it is for our group today. It was very rare for a community not have at least one blacksmith.
But how do you go from iron ore to a spear?
For most of the Celtic areas hematite and especially bog iron (goethite) were the primary sources of iron ore. But regardless of the ore type, a blacksmith can’t just heat this rock up and hammer it into a chisel, spear or nail. This rock is iron ore, not just “iron” and that means it’s got a lot of other stuff sticking to the iron molecules; and believe it or not the main thing sticking to the iron is oxygen. So how is that oxygen removed? The primary method is intense heat; around 3000F. Amazingly a simple charcoal fire when exposed to blown air can get that hot, and the most common method of delivering that air is with bellows.
Unfortunately, there are no known surviving Celtic bellows from the iron age so we don’t what kind they may have used. But the two most likely candidates are “bag” and “single lung” bellows. The former is a leather bag whose top can be squeezed shut as the bag is collapsed thus forcing air out a hole in the bottom. The latter is what most people think of when they hear the word bellows. In fact, this style is still included with fireplace tools today.
But even adding air to the fire to increase temp it can still take 6-8 hours to smelt ore. Unfortunately, the smelting process is not 100% effective and so a lot of ore (and charcoal) is needed to obtain a reasonable amount of workable iron. In fact if you’re lucky 100# of ore will only yield about 20-25# of iron. This means you’ve got to build a structure that can take 3000F temps for the length of time it takes to slowly add 100# ore and 100# charcoal.
The Celts solved this problem by building the “Short Stack Smelter”. We assisted building and running this particular short stack (with many others) at the Metalworking Symposium held at the Cooperstown Farmer’s Museum back in 2004. If I remember correctly, the person in charge of this smelter (Darrell Markowitz) went for a 50# charge and obtained 10# of iron after 7.5 hours. Oh, and BTW it took a 1-1/2 days to build the smelter prior to the smelt. As if that wasn’t enough, if you toss in the 2 days to make the 50+ pounds of charcoal, you’ve got a very time and labor intensive activity just to get a mere 10# of iron bloom. The iron bloom is the result of a successful smelt and looks kinda like a sea sponge.
But we’re not done yet! That bloom needs to be mashed down into a consolidated mass and eventually into a nice smooth bar free of all the pockets and impurities of the original bloom. Now, it’s during this refining that the smith may notice sections of the bloom that work harder than others. With experience the smith can segregate these “steely” sections out for special projects; tools, weapons, etc that need steel.
You see, steel is not a modern invention; it’s a by-product of the smelting process. Steel, is iron+carbon which is readily available from the charcoal fuel. So, as soon as man smelted iron, he was also creating steel. That said, the actually process that allows iron to hook up with carbon in the smelter is reliant on a number of variables, and therefore unpredictable. As if that unpredictability wasn’t bad enough, it seems that the skill level of Celtic smiths were widely variable.
The results of metallurgical testing show great fluctuations in heat treating methods employed by them. Briefly heat treating is the process by which the desired properties (such as hardness, toughness, or springiness) can be brought out in the steel. So, for instance, shears, at one geographic location, might be made from excellent quality steel but not heat treated at all, while an iron dagger elsewhere might have gotten worked with the old fashioned processes suitable for copper/bronze, or perhaps a spearhead was beautifully wrought with perfect tempering. Blacksmithing in the Celtic world was just too variable to make any generalizations about it’s quality or technological advancement.
If I was forced to guess I would say this is most likely the result of two main factors; their tribal/clannish nature preventing information/technology exchange and the availability of consistent quality resources.
Now, as far as blacksmithing proper is concerned, the techniques they used 2500 years ago are virtually unchanged from what I do today. There are seven core processes: drawing out, upsetting, bending, swadging, forge welding, punching and twisting all which date back to the beginning of ironworking. One of the few things that have changed over the past 2500 years is the size of the anvil and combination of once independent tools into the familiar anvil shape we use today.
But the overall continuity of methods is one of the nice things about reproducing Celtic ironwork. I can simply look at an archaeological artifact and deconstruct how the original, ancient blacksmith made it. The processes they used to create it back in 200BCE are the same I use in my shop today.
But what were Celtic smiths of antiquity making?
Tools for nearly every trade like:
- spoon augers
- Flesh forks
- Bails & Handles
Although the items in that list are far from exhaustive, you might have noticed a particular stereotypical item missing from this list. Horseshoes. Although the Celts were well known for their equestrian expertise, they rarely shod their horses. Why? No, need. Most roads weren’t paved, so the horses could easily go “bare foot” without incident. And besides, as we’ve seen, with iron as labor intensive to make as it was, iron weapons and tools were FAR more important.
Thanks Dan for this fascinating insight into how the Celtic Forge really works… it’s been great to have you on my blog today, I’ve really learned a lot!