Monday, 6 February 2012

The Twist-Welded Blade

The ultimate expression of the smith's art in the First Millennium was blade-smithing, especially sword making. A useful sword needs to be light, strong and flexible; and various cultures, using varying local iron sources have come up with a number of solutions to this dilemma over the centuries. 
The solution evolved between the 1st Century BCE. and the 9-10th Centuries CE. in Western Europe was to weld strips of iron of varying types together. By doing this repeatedly, a composite structure could be built up composed of soft but flexible ferrite and harder but more brittle low-carbon steel. This was tougher than ‘wrought iron’ and could be hardened by heat treatment. This technique could also be performed using rods of ferritic and phosphoric iron...

This "piled" construction became increasingly complicated and eventually developed, in about the 3rd Century C.E. into what we now call "Pattern Welding" - a horrible term first coined by Herbert Maryon in the 1940s to describe the complex patterns woven into the fabric of the middle of the blade during its manufacture.
Existing swords and daggers from our period are mostly in an eroded condition and soil acidity has often differentially etched the blade surface, making the complex patterns very obvious. Originally, academics proposed impossibly complex explanations and methods for these designs but in fact the techniques remain in use in the making of so-called "Damascus steel" shot-gun barrels and knives to this day.

How then would an Anglo-Saxon manufacture a Seax of heroic quality ?
First he would select rods of low-carbon iron, some of high phosphorus content and others of low phosphorus content. These strips would be forged up before welding to improve their grain structure and to adjust the carbon content of the components, thus imparting life and "spring" to the finished blade. Using three rods he would weld up a "sandwich" of high/low/high Phosphorus Iron. This would be repeated to produce four composite rods which would then be twisted, two clockwise and two anti-clockwise. These four twisted rods would then be fire-welded together. Two lengths of low-phosphorus iron would then be welded on either side.
About one third of each side of the pattern would then be ground away. (-not for nothing was a sword called "The survivor of the files") This would take considerable judgement and care.
The smith would then make and weld up a block containing a thick, inner core of hard steel surrounded by an outer layer of low phosphorus iron and (outermost) high phosphorus iron.
This edge steel (stylecg) would then be welded to the pattern-welded block. This would then be forged out to shape - a very time consuming process requiring great care, so as not to disturb the pattern. (~about 2½ hours vs. 20 minutes for a plain iron knife.)
The blade would then be ground, trued up and heat-treated. Great care needed to be taken while tempering as the blade is made of many different irons and steels. Heating gently releases some of the tensions in the metal structure. The piece would then be quenched i.e. cooled fairly rapidly, usually by plunging into a barrel of water. The quicker a metal is cooled the harder (but more brittle) it becomes, so this would entail considerable judgement.

Sword blade with two-twist pattern (Pb*)

The blade could then be ‘etched’ with vinegar to bring out the beauty of the pattern. The phosphorus-containing ferrite would have remained virtually carbon-free and remained bright when etched, whereas the non-phosphorus iron would have picked up a lot of carbon from the hearth, becoming carburized to about 0.1% and was, in effect, a steel. This etched darker, partly due to smaller grain size in the metal structure.
The intricate patterns obtained were of a regularly repeating nature. Many patterns resembled the markings on a snake's back. The Englisc thus called these curving patterns 'Wyrmfah' (O.E. wyrm - a snake, dragon + 'fah' -? related to 'feg' - "joining, joint" / 'fegan' - "to join, unite") Other Anglo-Saxon descriptive terms for these patterns are:
Atertanum - "with poisoned twigs / stripes", again suggesting the markings of an adder.
Brodenmæl - which I would translate as "Sprouting Pattern".
Hringmæl - "with ring-like patterns".
Sceadenmæl - "like the scales of a shad" (a fish).
Wægsweord - "sword with wavy pattern" and
Wundenmæl - "Twisted pattern"

Patterns formed in Anglo-Saxon knives and swords are many and various and depend as much on the forging and grinding as on the initial welding. If the pattern is not ground and forged in just
the right way, the most likely outcome was the common plain chevron pattern also called "The Reaper" or "Herringbone". How to obtain a particular pattern must have been a closely guarded trade secret!
The blade of a Seax could thus take a good smith at least 20 hours of hard work. The manufacture of a sword was thus infinitely more difficult and could take at least 75 hours. Construction would be similar although the amount of material needed would be greater and the chances of something going wrong in the welding much higher. This process of "pattern-welding", apart from being time consuming, would require vast quantities of charcoal, literally tons, and huge amounts of iron and steel, as approximately 15% of the iron is lost every time the workpiece is welded.

Spatha blade of "piled" construction. (Pb*) 

Pattern-welding was seen as a sign of quality and was used for some spear-heads as well as many knives and swords. As Anglo-Saxon civilisation stabilised in the 8-9th Centuries and better ores became available and smelting furnaces improved the need for the "pattern-welding" technique for sword-making disappeared, although seaxes continued to be made in this way.
Some swords may have also continued to be made in this way for ceremonial or funereal purposes. Actual 'War-Swords' were still made with a piled structure- with hard outer steel and softer, more flexible core but the surfaces were uniform. These later swords, however, often had twisted iron inlays forming letters welded into the blades. These often took the form of the maker's name e.g.. ULFBERHT and INGELRII. Phosphorus-poor iron was used, as in pattern-welding, to give shiny inlaid letters. These could be described by the Old English terms 'searofah'- "cunningly inlaid" or 'malswyrd' - "sword with inlaid ornament". In Old Norse, such a weapon would be described as ‘mál-fár’.

Important sources of information were:
H.R.Ellis Davidson's "The Sword in Anglo-Saxon England", Boydell Press 1962, and an internet article "The Serpent in the Sword" by Lee a. Jones. [which has excellent photos of patterns]. Also "Medieval Craftsmen - Armourers" by Matthias Pfaffenbichler, British Museum Press 1992; "The Anglian Helmet from Coppergate" by Dominic Tweddle. York Archaeological Trust 1992 and "Arms & Armour of the Medieval Knight" by David Edge & John Miles Paddock, Bison Books 1988. Kevin Leahy’s new book “Anglo-Saxon Crafts” was an invaluable aid, as was Zoëga’s “Concise Dictionary of Old Icelandic”.
Watching a real smith at work was also invaluable and I am grateful to Simon Stanley for all those evenings in the forge. Thanks also to master sword-smith Paul Binns who has allowed me to use some of his images.

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