I don't know whether many people here watched the BBC4 programme about Owen Bush making a kitchen knife on BBC4 the other night? I would have liked to understand a bit more about what he was doing, and why, at various stages of the process. Anyone got any comments?
I once watched someone make a knife at an event (a country show thing), he commented he had learned how to do it from Youtube.
He made it look quite easy but it obviously wasn't his first attempt. As I recall, he used sections of old circular saw blades (large ones, probably 12" in dia or more), which he had cut out with an angle grinder. He didn't show this bit, just the remains of the saw blade with the 'holes' etc.
He also mentioned that kits were available on Ebay etc.
The end results looked quite impressive, although I can't comment how well they actually functioned as kitchen knives. I've recently bought a couple of 'ceramic' kitchen knives which are very impressive, compared to a traditional steel knife. However, reading the instructions, they seem quite fragile- apparently they are prone to chipping. So much so that you shouldn't use a dishwasher! I've bought a special sharpener for them but not needed to use it yet.
I gave up on ceramic knives, drop one once and the show's over. More a specialist use thing than a household item.
NT
+1 Just stack a plate on top of one in the washing up bowl and it will chip/snap.
As a layman, it seemed that a lot of it was to do with making several strips of steel into one blade by heating them, bashing them, heating them, twisting them and so on. The end result was a blade patterned by what would have been lots of different layers.
I think this is called 'Damascus Steel'.
Just checked on Google Images. Looks like it is. It's very attractive.
Cheers
I wanted some explanation as to why it was twisted, whether that was done just once or more times, etc. It (the programme) seemed to be all about images, with no substance. We could see that Owen was working away, but not why and what he was trying to achieve.
Even the simple pickling process was not explained. We saw a blade being put in a jar, but had no idea what was in the jar.
I think the idea is that the blade ends up comprised of many very thin layers of steel which aren't quite a single mass, presumably because an oxide layer prevents them from becoming so. Twisting and flattening a wodge of initially quite thick layers seems to achieve this. I don't know what the arc welding was about.
He heated and quenched the blade in oil to temper the steel, and pickled it in something - probably hydrochloric acid according to Wikipedia - to remove scale.
The lack of explanation was maybe a bit frustrating, but would have detracted from the beauty. Maybe optional subtitles would have worked.
Cheers
They'd have to be optional. I liked the canal trip in the same series, but I found the superimposed explanations distracting.
The process goes back literally thousands of years when swords were high status objects. and had to look good. The swirls in thefinished blade were an appearance thing. Iron wa smade from "bloom" as temperature in a hand ventilatedfire were too low for modern methods. Steel was made by hammering the hot iron so breaking down and distributing the carbon granules. Bit on the topic here.
The layering makes the steel flexible. I didn't know the did it for knives, I've seen it done for swords before. In simple terms, more layers, more flexible, but there must be some kind of limit or point where enough is enough. Even a smallish number of folds will give a lot of layers, 10 folds gives just over 1000, 16 over 65000. (2^number of folds) .
While flexible, the knife can still be hardened and tempered, if it is the right kind of steel (carbon content is the main thing I believe).
The 'Make' programmes are part of the Four Goes Slow season, which are deliberately not voiced-over, and have no accompanying music ...
Didn't see the program but folding allowed craftsmen to forge the steel without the need for heavy equipment.
Hitting a bar of red hot steel with a heavy weight forces the carbon grains into the longitudinal shape of the bar. Of two bars of the same eventual size a cast bar would be brittle and would break across the grain which would be essentially random whereas the forged bar wouldn't, and would get stronger the more it was forged.
If you started with a billet of steel one ft deep and put it through a succession of hammers or rollers until it came out a quarter of an inch thick then that would probably be the equivalent of a folded bar which started off as a billet a quarter of an thick* and was folded 12 to 16 * times. Which is obviously easier to handle and heat in a small forge.
michael adams
*Japanese swords which were made in this way were folded 12 to 16 times* - although they comprised of two different steels - a flexible steel for the core and a harder steel on the outside to take the edge....
On 06/05/2015 23:43, GB wrote: ...
The twist was to produce a particular pattern. He probably only did it once, but that would depend upon what pattern he was trying to achieve. Depending upon how the metal is worked, you can produce various other patterns, such as bands of colour along the length or across the width or eye like ovals of different colours.
There should be no need to pickle forge welded steel. The hammering drives out impurities. However, the final step would be to put it into a solution of ferric chloride, to etch the steel. He will have used at least two different alloys and, after etching, they would give different colours, depending upon the alloying elements and their proportions. Manganese turns black, nickel produces a silvery colour while chromium gives a light grey.
Actually the original name of the game was to work the metal hard before it became a final shape and alter the chemistry in it.
Pure iron is very soft, but cast iron or newly smelted iron is too full of carbon - its so brittle its useless.
heating it and smashing it oxidises that carbon at the surface. You need to do that many times and expose the new surfaces to get a more ductile and elastic steel out of it.
Final quenching case hardens it to give a steel with a better ability to take an edge.
Bob Eager laid this down on his screen :
I didn't know what it was, or what it was supposed to be, when it came on, but I found it quite enjoyable too. I agree the captions were quite distracting and some of them difficult to even read. I would have preferred an occasional voice over.
I wasn't aware it was part of a series, I'll have to investigate. Reminds me of The Potters Wheel lol
I have a 12 bore shotgun with Damascus twist barrels. I vaguely thought the *etching* picked out the twist due to some metal being *end grain* and more susceptible.
On 07/05/2015 10:09, Nightjar There should be no need to pickle forge welded steel. The hammering
Possibly, but the programme showed all the steel being cut in strips off one sheet of metal. Then he welded them together before heating them up and bashing them (lots!). It would make sense to use two different alloys, but that was not shown. Quite misleading, really.
Also, whilst I am sure he folded the metal, at no stage were we shown that all-important stage.
If it gets too popular we will get the inevitable copy cat versions like we have had with gardens,house restoration/wrecking, cooking and so on. Some producer will put on two hours of paint drying and then another will come along and suggest an image of lines and blocks of colour in various patterns relieved in the middle by a picture of a little girl holding a balloon and left on the screen for hours on end would be a cheap way to fill some airtime for which they will get a standing ovation at a self congratulatory award ceremony.
G.Harman
A Time Team special from Sheffield did this - they showed how two guys with long tongs passed a red-hot billet through successively smaller rollers to make the steel needed for cutlery.
Apparently it was very high-risk. The slightest slip, and the rollers would pull you in.
Intriguingly enough, in the same programme, the archaeologists were totally unable to produce the steel needed using the 18th century techniques (which we know must have worked, since we have the steel to this day). They were unable to make a furnace hot enough. They resorted to cheating, and using a modern furnace.
And the sooner the better, if you ask me. As some people clearly weren't paying attention the last time around.
michael adams
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