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Tim Mitchell

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Tim Mitchell last won the day on December 10 2017

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About Tim Mitchell

  • Birthday 08/06/1975

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    New South Wales, Australia
  • Interests
    blacksmithing, knifemaking, wootz manufacture, carpentry, astronomy.

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  1. Tim Mitchell

    Wootz book by John Verhoeven

    Yes what he has recently released has made that a lot clearer for many. He recently published a paper on their work, just before he released the book. It had a big section on the mechanism of banding theories and how the "dendrite" arms could rotate in the grains and line up in cementite sheets. It was the best discussion on it that I have read ever... exactly what I would expect from John . This is the paper and it is well worth a read. https://link.springer.com/article/10.1007/s11837-018-2915-z
  2. Tim Mitchell

    Wootz book by John Verhoeven

    Thanks for the feedback on the book Gary, I look forward to getting a copy soon too. I know the material in it, but having it as a record on the shelf will be good.
  3. Tim Mitchell

    Wootz book by John Verhoeven

    Yes there are two that I know of on Youtube. The Mike Loades documentary about Al and a friend of mine from Jordan. The other was the Nova special about Ric making the Ulfbhert sword. Both are very good documentaries and with Al you will see there are many things that he does which reveal his process at that time, if you know what to look for.
  4. Tim Mitchell

    Wootz book by John Verhoeven

    I look forward to hearing your thoughts on it. I never met Al or John, but have chatted with them quite a bit over the phone and knew Al pretty well. I am glad that he finally shared their research publicly. It was a pain knowing their research for over a decade and not being able to talk about it except in general terms. I did appreciate Al's mentoring over the years though and what they researched is an important part of our knowledge of Wootz steel.
  5. Tim Mitchell

    Wootz book by John Verhoeven

    I just found out that John Verhoeven just printed a book about his and Al Pendray's work on replicating Wootz and their findings. I have yet to get a copy of it, but I know John and having read pretty much everything that he has written on the subject I know it will be well worth the money. It is currently selling for around $30 on Amazon. https://www.amazon.com/Damascus-Steel-Swords-Solving-Mystery/dp/6139884837/ref=sr_1_1?s=books&ie=UTF8&qid=1535108423&sr=1-1&keywords=john+Verhoeven Al and John focused on one specific type of patterning in Wootz, the Black Wootz or Kara Khorasan pattern. Their findings were focused on that pattern, but most of what they found out also applies to the general world of Wootz making and John, being a top notch teacher of metallurgy, will not disappoint I am sure. Tim.
  6. Gary, there were many sizes of ingots depending on the different uses and also the process used and the location.... and the century. Some ingots were round flat loaves, others were egg shaped, others were as you describe (from Hyderabad). The crucibles were sometimes fully closed and sealed, other times they had a hole in the lid to insert a rod, and other times there was no crucible at all (a bloomery furnace floor melt). The furnaces were in some cases open, heating the crucibles from below, some cases closed fully as you describe (at Merv) and some times able to be uncovered, checked and covered once again such as was used at Hyderabad in their round the clock process. It was there that they needed to know if the crucibles were ready to remove because of the cyclical process. As you can see, there were many different processes used in many different locations over a time period of close to 2000 years. Some crucibles were shaken, others were not but the final product was not controlled by the shaking, it was just a monitoring method. Much has been written on the web by misinformed individuals and some hold the understanding, incorrectly, that there was one "Wootz Process" which there was not. The only things that were consistent between all the Pulad/Bulat/Wootz processes was that a high carbon steel was produced and solidified into an ingot through medium to slow cooling and the resulting ingot was forged out into blades, tools or other useful items. Some ingots did not produce patterning due to insufficient dendritic structure in the ingot (through quick solidification), through incorrect forging temperatures, or through the ingots being so small that there was not enough reduction of thickness in the ingot to make the pattern visible. The ingots from southern India and Sri Lanka didn't produce a watered pattern as the ingots were rod like and too small in diameter, they were made into scissors, punches etc. There are few true researchers in this field and even some of the historical information can not be relied upon 100%. First hand accounts are the only accounts which are significant and what people said of the ingots in the past may or may not be true. It is a difficult task to weed out the facts from hearsay and rumour. Cheers, Tim.
  7. Hey Al, Your thoughts are good ones, but none of the things that you are asking about would make any difference to the patterning. The shaking of the crucible would be simply to hear if there were any clacking from metal pieces which were not fully melted. A crucible that was ready would have a fully melted charge and shaking the charge would in a similar way to getting bubbles out of concrete, cause some settling of the charge. However it would still need to sit long enough after the shake or there would be a risk of having slag inside the ingot after it solidified. The internal microstructure and microsegregation only begins to form once the ingot starts to solidify and the dendrites start to grow from the outside in. They will always grow from the same place and only the cooling rate will control the size of the resulting dendrites. The dendrites are the core building block of the patterns that are formed, without them there is no pattern it is that simple. It is what happens during the speed of solidification (size of dendrites) and the roasting period (dissolving secondary dendrites and increasing spacing of banding) and the subsequent forging temperatures (controls carbide shape and cluster sheet structure) which causes differences in the patterning. All of these patterning factors occur after solidification and are totally unaffected by the shaking of the ingot charge. One other thing that controls the way the pattern ends up is the proportion of reduction in the thickness of the ingot. Larger ingots have a higher degree of reduction than smaller ingots. This could explain some of the differing pattern characteristics through different centuries. Abbott drew a pancake style ingot that was forged edge on, this would have been about 5 inches in diameter and was from a different process which was used in the Salem district, melting steel prills in the floor of a bloomery furnace. Not all Wootz was crucible steel... unless you consider a quartz grit covered bloomery furnace floor to be a crucible, which technically it is. These are the same pancake style ingots which Joseph Banks received with the cone style ingots, all of which came from southern India. The ingots from Hyderabad area went to Persia and were not examined by the early scientists in Europe. The ingots from India, described in the 16th to 18th centuries were not the ones that we think of from Hyderabad/Deccani, or the Persian egg shaped ingots, but they are the pancake, buns of steel which were described to be like the size and appearance of a penny loaf. Penny loaves were round flat and about 5 inches in diameter. Other patterning differences can come from the use of shaped hammers and different forging techniques even if it may not be immediately visible to the average observer. Also the different trace minerals which are in the ingots can make a difference in the way the pattern displays, contrast etc. Hope that helps and good luck with your steel making, I look forward to seeing what you come up with! Tim.
  8. Tim Mitchell

    Reflection to the ancient steel.

    Really nice pattern Niko!! It is awesome when you get that consistency down and you can choose what pattern you want to make each and every time. I love that blade shape too, really nice. I can't wait to see what the finished blade looks like. Keep up the good work!
  9. Tim Mitchell

    Reflection to the ancient steel.

    LOL Yes...All patterns are repeatable it is just a matter of knowing how... It will be good to hear eventually what that method is. It will be helpful in the learning of many smiths. Niko does some really nice patterns and I am really happy for him that he is getting consistency now.
  10. Tim Mitchell

    Reflection to the ancient steel.

    Very nice fine spherodized groupings Niko! You have a very nice pattern there. Good work!
  11. Tim Mitchell

    Definitions and history of "Wootz" and such

    KONASANDRUM PROCESS AKA DECCANI PROCESS: (1820-1823) from repeated visits and inspection of the process by Voysey. "Native manufacture of Steel in Southern India" - Journal of the asiatic society no.6 june 1832 p 245 [Extracted from the Journals of the late Dr. Voysey] "The granitic clay of the furnace is highly infusible; it is found in the neighbourhood, and is formed of the decomposition of granite rock with small pieces of quartz and felspar, and is so valued for its refractory qualities, that it is exported for the manufacture of crucibles, &c. In making the crucibles, the granitic clay above described is ground to a fine powder along with the fragments of old furnaces and crucibles, and the whole kneaded together with the chaff of rice and oil. The vessels are defended by a luting of the same, they are covered with a similar top, but a perforation is made in the latter. No char- coal is put into the crucible, but small pieces of kanch, or the glass formed in the process, are put at the bottom of them along with the ore, and serve of course as a flux. The crucibles are arranged and steadied in the furnace occasionally by the superintendent, with a long and stout rod of iron. The materials used in the preparation of the steel are two different kinds of iron; one from Mirtpalli the other from Kondapur, in the proportion of three parts of the former to two of the latter. The Mirtpalli iron is derived originally from the iron sand already noticed, and is sent in the state of large amorphous masses of a redish grey color, and of an extremely porous texture. The internal fracture is often iridescent. The Kondapur iron is procured from an ore found amongst the iron clay, at a place about 20 miles distant. It is said to be of a dirty brown colour, and very frangible. The Iron however, is moderately compact and of a brilliant white fracture. Occasionally it contains some ingredient which spoils the steel, render- ing it excessively brittle : the natives assert that the adulteration is copper, but it is more probably arsenic. The mixture being put into the crucible, the fire is excited and kept up for 24 hours. It is then allowed to subside, arid the crucible is taken out and placed on the ground to cool. When quite cold it is opened,and a cake of steel of great hardness is found, weighing- on an average about a pound and a half. The cake is covered with clay, and annealed in the furnace for 12 or 16 hours. It is then taken out and cooled, and again annealed, and this may be repeated a third or fourth time until the metal is rendered sufficiently soft to be worked. The steel is known by the name of Wootz in Telinga, and a Kurs, a cake of about 110 rupees weight, is sold on the spot for 8 annas. The daily produce of a furnace is about 50 seers, or in value 37 rupees. The cost of this steel is much enhanced by the exaction of the Jaghirdar who not infrequently appropriates the advance to himself, and leaves the purchaser still to incur the whole expense. The export, however, of the metal to Persia must be profitable, as it is sufficient to bring dealers from that country and to defray the cost and risk of traveling. We found at the village, in 1820, Haji Hosyn, from Ispahan, engaged in the speculation ; and it must have answered his purpose, as he was here again in 1823, having returned in the interval to Persia and disposed of the venture. He informed us that the place and the process are both familiar to the Persians, and that they have attempted to imitate the latter without success. Besides residing at the village, whilst making his purchases, he bore a personal part in the operation, weighing the proportions of the iron, and toughness of the steel himself."
  12. Tim Mitchell

    Definitions and history of "Wootz" and such

    Here are some observations that I have compiled from different accounts over the last 350 years concerning the ingots which were sold to Persia for the making of Damascus Swords. Observations of the steel cakes from Golconda, (Hyderabad, Deccani, Konasandrum): The Golconda process was a carburising process where cast iron was added to iron with a lower carbon content. 1675 Tavernier: - The steel from Golconda is the only steel which will take a Damascene pattern. - The steel buns were in the past mostly sent to Damascus when trading went from India to Cairo through the Red Sea. - The steel cakes were sold to Persia and the Punjab for the making of blades from Hyderabad (editors note) - The Persians know how to Damascene with a sulfate etch. They can’t do it with their own steel. - The cakes of steel are large, the size of a Penny Loaf () and are cut in two. - Each half makes a sword. - These buns of steel are made in Hyderabad in the kingdom of Golconda (Deccan) and reported to be the best from the villages of Nirmal and Indore (editors note) Scott 1795: - “The specimens of Wootz were in the shape of a round cake of about 5 inches in diameter, and one thick; each of which weighed more than 2lb. The cake had been cut almost quite through, so as to nearly divide it into 2 equal parts. It was externally of a dull black colour; the surface smooth; the cut part was also smooth, and excepting a few pinny places and small holes, the texture appeared to be uniform.” Muchet 1805: - one of the cakes had two cuts in it cutting it almost in two so it was easy to break and see the quality of the steel in the middle broken section. He interpreted them as the result of crystalization, but also declared they could be cuts. These were the ingots which Holland declared were the ones made in Salem by the bloom process as they had occlusions of rust in some of the underside portions. Abbott 1856: - mentioned by Abbott in the Punjab Goorjrat, a 2 lb ingot which was lenticular in shape, was forged out into a bar in about 2 hours by the smith at a white heat (red heat according to edited version) This was available to be bought in Deli. - This ingot was not partly cut in half but was complete. - Dimensions were loaf like and about 5 inches in diameter and about 1 inch thick. - Were available in both large and small ingots. TL Lowe: - examination of the remains of crucibles from Hyderabad region Konasandrum, shows crucibles from 1 inch to 5 inches interior diameter. The 5 inch diameter ingots are the ones which the above reports are mentioning. NOTES: - It seems that there was a mixing of ingots, some from Salem and some from Hyderabad, arriving in Bombay and this accounts for the ingots which were clearly made from separate processes which both Joseph Banks obtained and which Smith sent to the royal society. Some ingots had oxide remains in pits on the underside as described by Muchet, and these were actually from Salem further to the south according to Holland's account in the 1890s. - It seems that the almost cutting in half of the ingots was stopped somewhere between the late 1700s and the mid 1800s. Although it was clearly a long standing practice. - Tavernier said that the Persian steel, although very good, did not produce the Damascene process. We know that in earlier times the steel from Persia did in fact produce patterns. However it is possible that in the later years the steel from India was found to be superior and replaced the steel from Persia. We know that Persia used large quantities of the steel from Hyderabad.
  13. Tim Mitchell

    Definitions and history of "Wootz" and such

    The refractory clay which was used for the process in Hyderabad was a granitic clay which was high in quartz and in feldspar, it was exported as a highly refractory clay specifically for crucible use. If you make your own crucibles make sure you go either very high silica content (add lots of silica and quartz grog) or make it very high in alumina content. Try to cut it with pure silica or alumina to reduce the content of fluxing ingredients in the clay. You can also add wheat chaff from the feed store if you want to, it will help to make a more refractory crucible. Prefiring the crucibles is also a must if you aren't using a charcoal fire and slowly raising the temperature. The process at Hyderabad took 24 hours so the crucibles were being prefired during the melt ramp up. Using an unfired crucible in a gas furnace is not an option. It will explode... been there done that and had lots of flaky chips of ceramic dancing around in the furnace. It is a real bear to clean out too.
  14. Tim Mitchell

    Definitions and history of "Wootz" and such

    I was asked about historical recipes for wootz and if we could add some to the thread. This first one that I am adding is the process from the Mysore region of India. It is important, in that it is one of the processes which is associated by many to be how they made the blades which we term Damascus blades or Wootz blades.... Some of these ingots were not used for producing blades, there were also variations of the process as will be seen from the excerpt that I include below. I was going to post it in the form of a summary, however I think it is better if the whole account is read to show how the processes in this one area were similar but also different. I have a copy of Buchannan's personal published account, but it differs so much from this account here that I really don't know what to make of it. Perhaps this was from a personal diary or a separate published account I don't have a copy of. Anyway the accounts here are more precise. This article excerpt was written in 1864 with the accounts going back to 1800. Southern Indian Wootz Accounts C1807.pdf
  15. Tim Mitchell

    Definitions and history of "Wootz" and such

    Not quite Daniel, I have always used a 16lb hammer one handed to forge 2kg ingots, it does take awhile and probably longer than some have patience for, but it works fine. If you get impatient, rope a friend in as a striker, it makes a real big difference! As far as crucibles, for a 2 kg ingot you will need around a #6 bilge sided crucible. You can make a crucible which is taller and slightly narrower if you so desire, which will make a more egg shaped ingot.