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MacKINNON last won the day on May 20 2021

MacKINNON had the most liked content!


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  • Birthday 10/02/1965

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    Taranaki, New Zealand

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  1. You are not alone in chasing nuance. I made six or seven just trying to get a form that suited a new kashira die I had made. I arrive at a example I find pleasing only to reject it a week later. I don't think this little game ends any time soon. I think your work is pretty impressive. I especially like your inlay techniques. Inlaying and producing a clean ground without surface texturing is no mean feat.
  2. Shibuishi is an awful alloy for splitting seams. I'm not surprised you had some issues. One of the handy things about forming them in the round is that you can then work one edge over a standard ring mandrel to form a slight cone. When you shape this up it forms ' funbari', ( Stradle) , that is, the fuchi takes on some flaring at the seppa. It makes for a more subtle form than a simple parallel ferrule.
  3. Thanks for the explanation. I do the same thing, but in the round, with soft materials, knocking them into shape after soldering. It doesn't work very well with iron or harder alloys as even a reinforced joint generally can't handle the stresses of hard shape changing. Me too. I get very sheepish talking about koshirae as invariably my friends in Japan waive their fingers at me and ' tut,tut'.
  4. It is my understanding that using panels of Samegawa was a reaction to material shortages after the closing of Japan by the Tokugawa shogunate in the 1600's. 'Belly meet' and 'overlap' wraps were still used, but only by the wealthy Samurai. Using panels is also technically a lot easier to do than either of the full wrap versions. Late Edo tsuka are often seen with multiple small panels of Samegawa cobble together.
  5. Beautiful work. I'm wondering why you joined the fuchi in the middle rather than than traditional join on the mune ?
  6. It does have it's moments in the North Island. View from my old factory.
  7. Right now, the view is less inviting. Just waiting for the start of a week of rain.
  8. Are you pitching for a job at Tourism New Zealand ?
  9. Mr. Schneider, I have shown you the little I know. I have given my opinion of the use of modern coatings on crucibles. I'm sure you will develop your own recipes from research and experiments. I am a tradesman, not a teacher. Good luck with your endeavors.
  10. Just a couple of broad strokes. In high temp wares, clay is often your enemy. Yes. I know, it sounds stupid, but if you think of clay as a 'green strength' binder that holds together the more durable materials until they solidify at higher temperatures, you're getting my point. Try to keep the clay content as low as practicable. All they clays I used , whether Fire Clay , ball clay or Kaolin are all high Alumina clays. In some trials I tried high iron, terracotta type clays. In low %'s , some made reasonable non-ferrous pots but most just melted at stoneware temps. And as for historic practioners. It's very difficult to remove people from their materials environment and understand how they did things. Until recently, many of the 'unlikely' ingredients in old recipes were brushed off as 'magic' or 'myth'. Modern analysis has made their purpose known. An example would be straw ash. Straw ash is used in Japanese Tanren forging and in many old crucible recipes. In Europe, silver sand was used as a flux for wrought iron, but not for steel. The liquid/solid phase for steel is simply too low for coarse silica to melt. However, the silica in Straw stalks is in the 8-12 um range and will act as a flux at much lower temperatures than sand. So, the prevalent idea for many years in the West, that the Japanese used straw ash predominantly as a carbon source have been proven wrong. Likewise , straw ash ( colloidal silica in the 8-12 um range) in pots is now embraced by numerous high tech patents for carboniferous refractories as it has been found to coat graphite and prevent early oxidation. Another example would be a Japanese iron patination solution that contained frankincense. Seems a bit bizarre but does make for a nice smell. Until, you talk with a biochemist working at an essential oils lab and she inform you that Frankincense under heat breaks down to a hexane component that would act as a de-greaser. The history of archaeo-metallurgy is replete with mysteries compounded by assumptions about our predecessor skills and knowledge, or the lack thereof. FYI Graphetised coke is a fine carbon make from petroleum products. It is identical to the coke build up you get on oil burning furnace injectors through incomplete combustion. It is far less dense than flake graphite , with an open , porous structure. It tend to burn out of pots before the body has sealed at high temp , therefore leaving a less slag resistant surface but an open fabric with much higher thermal conductivity. Very similar to the purpose of charcoal in Japanese blade clay. My hypothesis is that controlling thermal conductivity is why both flake graphite and coke dust are found in the 'Berlin' crucible formula.
  11. Pots are serious business, and I don't even like clay ;-)
  12. Giving you a simple recipe isn't that easy. I was not making wootz but was trying to make large, first stage direct reduction pots, similar to the process described by Needham as in use in Shanxia, China in the 19th century. First, I talked with potters. After numerous clay trials I gave up on potters as being particularly useless and began reading patents. I followed them back through 'patents reference by' until I arrived at formulas I understood. Then I moved forward in the patent search trying out new formulas and recipes. Once I had a reasonable handle on the technology. I was able to talk with Ceramic Enginners without them putting the phone down on me in disgust. They really are very, very knowledgeable people who don't suffer fools gladly. The phrase, 'You're not even wrong' is a fond memory. As you can see but the pictures of my trial notes, I tried all sorts of patents and variants. Outside of very sophisticated ingredients and manufacturing methods I found four, basic starting points. Tradtional clay graphites, like Berlin pots. Prof. Vasily's bulat pot recipes amd my variants My own shrinkage adjusted, clay graphite pots. And, a TiO2/ clay, silicon-carbide recipe I based on a patent for 'Self healing' crucibles. I tried a lot of different things. I tried powdered aluminium addition to create 'Exothermic, internal drying' of clay bodies. I tried borax addition to create 'self glazing' pots and colloidal silica additions to prevent graphite oxidation ( OK for low temps but at steel ranges the whole pot just went into solution ). Almost all of the carbon/clay pots will work for standard uses. Flake graphite is what you need and that posed my biggest problem, because of where I am. I was forced to use graphite furnace charge , made from ground electric furnace eletrodes or substitute with graphetised coke. Those I made with good grade graphite flake worked fine but were uneconomical to make. Shrinkage reduction pots. I won't go into detail here but clays shrink when they are fired. They shrink at known rates. Kyanite expands as it converts to mullite. It converts at the same temperatures as clay contracts. Hence, you can add kyanite in amounts to ballance this shrinkage making your pots ( in theory) more easier to fire and less susceptible to thermal shock Standard 'Berlin' crucible recipe fire clay 40% Graphite 20% Powdered coke 25% Grog 15% ( traditonally ground broken crucibles) I took these % by weight A 9kg bre would be 3600gm Fire clay, 1800 gm graphite, 2250 gm powdered coke, 1350 gm #200 grog. My shrinkage adjusted Berlin Fire or 'Ball' clay 22% Kyanite 42% Grog 20% Graphite 16% Prfessor Vasily's bulat pot recipe follows a 7.3,1 ( or 2) ratio 7 parts volume Flint clay ( I used chamotte or 'flint grog. This isn't a clay but a hard, fired material) 3 part fire clay 1-2 parts grahite. This is quite a tricky brew to mold as my chamotte was a a bit coarse. It would probably do well in a rammed mold. If you could find a finer chamotte, this recipe would be worth a second look for small, round wootz pots. I made a variant that was shrinkage adjusted and used a finer, flint grog. It was much finer in texture and really quite tough for 'one off' use. firedc clay 25% Graphite 6% Kyanite 47.5% Mulite 9.5% #200 flint grog 15% A brew that was quite promising in A8 size, rammed pots. This has a TiO2 addition to create a 'self repairing' crucible as per the patent. A similar patent included 5% metallic aluminium powder. Once made into a wet clay, the water/aluminium reaction is claimed to dry the pots from the inside and result in Al2O3 additions. I made about 9 variants of this and had to pack up my whole shop and move it before all the trials were done. I did several recipes with alumina additions, but both the alumina and the metallic aluminium didn't seem to make any positive difference to this basic TiO2 recipe. For the test pot , I replaced graphite with graphitized coke, simply because I couldn't afford more graphite. It handled a 2kg cast iron melt but did show scouring at the slag zone. It was also very thermally transparent ( probably because of a porous structure caused by the coke loss) and the iron melted in a record time for my setup. I would definitely try this one again with flake graphite in a rammed mold. Fire Clay /ball clay 35% Graphite/G coke 45% silican Carbude #200 17% TiO2 3% Glazes I tried a lot of different 'washes' to try to prevent carbon loss during bisque firing. One turned out fine for high temp pots. Sil. Carbide powder (fine) 164 gm Kaolin 36 gm TiO2 20 gm Al2O3 20 gm Silica flour 20 gm Water to form slurry. Painted on bisque fired pots, dried and furnace fired under use to stoneware + temps. I did some with a anhydrous borax addition and these produced the nice, chocolate colour you fine on commercial Borosilicate i.e. clay graphite pots. Fine for non ferous but degraded badly at steel temps. A simple borax glaze brew I developed for non ferrous pots, 2 heaped teasoons of Kaolin 1 teasoon anhydrous borax powder 4-5 teasoons silicon carbide powder ( 1200#) I did make several non-graphite pots which worked well at low temps but grapite is the main 'ant-wetting' agent in clay pots that stops slag errosion at iron and steel temperatures. I'll post a few picture of my notes so you can get some idea of the volume of trials I did between 2004 and 2008. In the end, I decided to bypass crucible refining and allotted to make a small, tilting open hearth furnace for the Basic process. These note are only a fraction of those made over the four years. It might be a quick read but it cost me a lot in time and resources when just putting food on the table was a struggle.
  13. I did similarly with little good effect. Most often the wash simply puts more of the pot into solution at high temps. I tried ITC Turdish liner in the early days and found that it handled slags OK but impacted thermal transfer to he charge so badly as to make the whole exercise pointless. These lining are used on pots used to transfer molten iron and steel, not for melting in a standard crucible fire. As I said previously, there are many things that will handle molten steel slags but they tend to be highly insulatory, making melting in a small crucible furnace very difficult.
  14. I'll have to find my notes from 15 years ago. Half the issue is that pots need to be thermally transparent as well as slag resistant. If they simply insulate well, then you don't end up melting anything unless you are running induction. I've tied all sorts of glazes, washes etc. and I have found that a simple kaolin/alumina wash will increase the life of pots if used on the inside.
  15. I made a few Silicon carbide pots using a molasses and flour , carbonising binder. Could never get the things to bisque without turning into piles a asphalt in the kiln.
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