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Forging a One Piece Bronze Corinthian Helmet
Corinthian helmet based on one found at the Marathon battlefield.
One Piece Helmets of the Ancient World
When you go to some of the bigger museums in the world, like The British Museum in London, or the Royal Ontario Museum in Toronto, you can take a walk to their Ancient Greece sections and see some interesting bronze helmets. They are amazing, because they are forged from one piece of bronze, and oftentimes have a fairly complex shape to them.
Now, it can be pretty time consuming to make a helmet out of multiple pieces, and rivet those pieces together. Helmets made like that can be pretty amazing. How does one go about making a flat piece of bronze into a 3 dimensional object that fits onto a persons head? We'll take a look at that here, using as model a Corinthian helmet.
The Corinthian Helmet
The term Corinthian is used to describe what is probably the most common type of Greek helmet. This sort of helmet has a bowl shaped area to cover the head, coverage for the nape of the neck (oftentimes, but now always, sloping in a graceful manner) a nasal piece to cover the nose, and cheekpieces that cover most of the lower face. Many ancient helmets have cool sounding names given to them by archaeologists that are just arbitrarily selected. Corinthian helmets are actually mentioned in one ancient source, we're just not sure if this helmet type is what was referred to. It is such a common helmet, both in ancient Greek artwork and in archaeological finds, that experts assigned it the name from the ancient written source.
The particular Corinthian shown in the pictures here was a commission by my friend, author Christain Cameron, who writes historical fiction novels about the Ancient Greek world (the Tyrant series, and Killer of Men). Christian is also a reenactor, and will be using this helmet in simulated battles. The original helmet from the Marathon battlefield that Christian wanted his helmet based on is in the Royal Ontario Museum in Toronto where he resides. I was able to study the helmet up close in the museum several times before work began.
The technique used to make such a deep helmet is called Raising. It uses mostly compression of the metal to shape it into a deep concave shape. The metal actually thickens a bit, mostly towards the outer part of the helmet, as a result of the compression making the metal "pile up" (more metal pushed into less space). This is in contrast to what is called "Dishing" or "Sinking", where the metal is stretched, and can only be stretched so far before it cracks.
The helmet started as an oval disk of bronze, around 2 feet long by about 22 inches wide. The bronze thickness was a little bit more that 18 gauge. I marked the center of the disc as a reference point, and then marked concentric circles over most of the surface of the disc, spaced about 1/2 inch from each other. These concentric circles would be guidelines for hammering.
Once marked, I placed the edge of the disc on the end of tool called a raising stake. A raising stake is a blunted bar of steel that will support the bronze as it is being hammered. For the hammer, I use what is called a cross-pein hammer, which has one blunt face, and a narrow face that runs crosswise to the hammer handle. Using the narrow face of the cross pein hammer, I use it to strike the bronze, aiming to hit metal in the outermost ring, hitting it just beyond where the bronze makes contact with the raising stake. I drive the bronze down a little in one spot, rotate the disc clockwise, strike again in the next spot, and so forth, driving down all the bronze in the outermost ring.
I then move to the next ring in, and repeat the procedure, and so forth ring after ring, until I reach the innermost ring, whis is about 3 inches from the center of the helmet. At this point, the helmet as a very rough, slightly dished look. Each ring that was pushed down towards the raising stake by the hammer added a little bit to the dish-like effect. I then repeat this procedure, but start from the inner ring and work outward, this time not trying to move the metal so much as to smooth it out.
When I finally get back to the outer ring and finish hammering it, i have completed "one pass". I then anneal the bronze, which involves heating it to a cherry red colour with a torch, and letting it cool slowly.
After about 8 such passes, the helmet looks like this:
After a few more passes the helmet looks like this (the oxidation has not yet been cleaned from annealing):
You can see that the central part of the helmet becomes narrower more quickly then the outer parts of the helmet, which tend toward staying flared out. The degree of metal that is moved,and the amount of slope that the metal has in different parts of the helmet can be adjusted by the angle at which the bronze is held on the raising stake, and to some small degree, the angle at which the hammer strikes the bronze.
After a few more passes this shape is reached:
I can actually temporarily mark in the prospective locations of such features as the cranial ridge, the eye holes, nasal, and outlines of the cheek pieces. The helmet bowl is fairly completed as far as raising goes, i.e. it doesn't have to be put through any more dramatic shape or volume changes, but will still need a lot of shape adjustment to become smooth and nicely rounded.
Work continues with drawing in the cheek pieces, drawing in the nape of the neck, and having the nape flow into the dramatic flare that forms the tail of the helmet. Here's a sequence a photos to help illustrate these steps:
Around this time I can set to working the nasal into the helmet. I use this stake to support the bronze from underneath:
Then I sculpt in the shape of the nasal, and the eyeholes, with both a narrow-faced raising hammer........
.......and a dull, rounded chisel struck by a hammer. The sides of the nasal get worked down quite a bit to give it depth and structural strength.
Adjustments are then made to the nape of the neck and the back most part of the helmet bowl. The nape is pushed in a bit with a raising hammer on the raising stake, and the helmet bowl is rounded out by working it on a round ball stake. Some planishing is done to the overall surface of the helmet, by using a polished, wide faced hammer. The face of this hammer is somewhat flat, but also slightly rounded so that it smooths the surface of the bronze gradually with a low chance of making marks by accidentally hitting with the edge of the hammer.
At this point I traced in the ravens onto the cheek pieces. Some sizing experimentation was needed to get the right proportion. Backing the bronze up with a chunk of lead attached to the surface of the raising stake, I chiseled in the outlines using various curved and straight dull repousse chisels. I then placed the outer face of each cheek piece onto a wooden stump, and hammered out the ravens from the inside with a ball pein hammer, getting them into a somewhat rough shape. I then filled each raven in turn with hot lead, and backing the lead up once again with the raising stake, worked the surface of the ravens with various smooth hammers and repousse chisels around the edges to make the shape smoother and more consistent.
Next, it was time to cut away the excess bronze. I drilled some pilot holes in the eye openings, and chiseled them out with sharp cold chisels backed up by a steel stake. I used a cutting wheel on an angle grinder to cut away the excess from around the base of the helmet, and from the rectangular facial slot.
A number of Corinthian helmets that I have seen in museums have thick bronze soldered into the underside of the nasal for reinforcement (these of course all had the deep, 3 dimensional style of nasal and not the flat-plate type that you see on some helmets). The Marathon Corinthian seems to have nasal reinforcement as well, so I soldered in a thick piece of bronze built up from several layers of sheet.
After this, I went over the helmet again with the planishing hammer, trying to get it as smooth as I could to reduce the amount of sanding (and hopefully reducing the amount of bronze lost from sanding). Then I sanded the helmet with an angle grinder, mostly using flap wheels starting from 60 grit, then 80 and 120. From there I went to flap sanding wheels mounted on a bench grinder, with the grits of 180 and 320. Then I buffed with a cotton wheel, using Dico's buffing compound for stainless steel (which works great on bronze).
I also drilled holes around the perimeter of the eyeholes, nasals, facial opening, and bottom edge of the helmet, like on the original. These holes are for sewing in a lining.
I built a "J" style crest and mounting out of bronze and wood. The bronze "J" and mounting is shown in Peter Connolly's book, "Greece and Rome at War". I soldered the mounting pieces(basically small bronze tubes) onto the top of the helmet with a low temperature solder. The "J" piece is held in place by pins pass over the base of the J and through the bronze tubes. Christian wanted white, red, and black horsehair, so I glued those colours of horsehair into holes drilled in the crest box. Christian wanted to paint the crest box himself, so I left it unpainted.
So, the next time you see a helmet like this in a museum, keep in mind the large amount of work that went into it. Under that green patina left by 2000 plus years of being in the ground, there was a lot of careful metal craft that went on.