Wednesday, April 11, 2007

On the Sutton Hoo Sword

(from an ongoing discussion with Catherine Crowe on Iron Age artifacts)

> So if all the swords are coroded piles of dust how do
> you know they were pattern welded? ...

If you think of a badly rusted piece of wire cable you might get a picture. The various types of iron alloys used as the layers in the pattern welding degrade at different rates. So even oxidized there is a visual indication. Any real details are reveled by X-rays. They take swords expanded inside bronze scabbards and can X- ray those to show internal details as well.

> ... Or if they had
> designs on them? I found a replica of the Sutton Hoo
> sword - and it had interlacing right on the blade -
> which struck me as fanciful - but maybe I'm wrong?

Absolutely! I've never seen interlacing on an artifact blade.

Sutton Hoo is the most complex sword of all the surviving pattern welded type. Its relative (!) state of preservation also is why it is commonly used as an example.
Although the artifacts are Saxon, take a look at:
Angela Care Evans 'The Sutton Hoo Ship Burial' ISBN0 7141 05449
The book shows the sword (blade x-rays) as well as the cauldron hanger I mentioned earlier, plus that elaborate helmet (the iron base is relatively complex for the period).

I may have mentioned that this sword has eight core rods. Each is twisted right / left / straight in regular sequence. The straights are set on edge so the lines of the individual layers show.
Now the rods are set four on top, four on the bottom. On each of top and bottom, the rods are further set in pairs right and left.The twists are done so as to alternate in a pattern that is matched by pairs, side to side and top to bottom - this diagram as you look at the surface of the blade:

\\\===/// top four

===\\\=== bottom four

This is a repeating pattern down the whole length of the centre of the blade. Notice how the straight sections on the top will match up with twisted portions on the bottom. (For a clear discussion of this see Langton & Engstrom, 'A modern replication based on the pattern welded Sword of Sutton Hoo, ISBN 0 918720 289 X )

There is an argument to be made if this type of elaborate patterning was enhanced by the use of lightly etching the blade. Note that modern practice is to use acids not available before about 1300. At the time of Sutton Hoo (c 625) the choice would be salt water / urine / vinegar. Salt water is really a controlled corrosion and I would suggest not likely for that reason. I have experimented with vinegar and it will produce a slow discolouration of the various alloys in the layers that helps to slightly highlight the patterning. (No - have not done urine - yet!)

Now - there is good archaeological evidence for two other methods to decorate sword blades. That would be engraving, or inlay of other metals. Engraving is cutting into the surface with fine chisels. Inlay is most typically either silver or sometimes gold. An engraved channel is cut and the softer metal hammered into the groove. Most commonly these methods are used to add text inscriptions. This also tends to be only seen on POST CHRISTIAN objects - the texts normally in Latin.
There are sometimes makers marks found on blades. These are usually hot punched during forging as you have seen on my own work. Its safe to say this is not about decoration as much as ownership.

I suspect that what you saw as interlace on that 'replica' was very modern acid etching. You may remember that I have done a LOT of this method in the past! Never to be found pre 1300 because of there being no acids available that would cut the metals.
I further expect that you would not find any kind of interlace etching applied to a real pattern welded blade! It would be like adding gold paint on top of real enamel work. Modern acid etching is relatively easy to do - unlike producing a pattern welded sword which is EXTREMELY difficult. I have also seen modern blades with a photo etched 'pattern' applied to they that attempt to duplicate the look of an etched pattern welded blade.

The price on a modern sword will tell the story here. Real hand forged pattern welded swords cost in the multiple thousands of dollars. Scott Langton, who made the replica of Sutton Hoo now on display in the British Museum, said once that a duplicate would run roughly $25,000 US (thats in 1990 dollars too).

1 comment:

STAG said...

Malaysian Keris makers still use lime juice to develop the pattern. I have not been able to get it to differentiate between high and low carbon steel though. Between stainless and carbon problem.
I now use lime juice to darken blades, gun barrels, and armour. Makes a nice dark antiquey grey.


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