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Darrell @ warehamforge.ca

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About Darrell @ warehamforge.ca

  • Birthday 11/03/1955

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    Wareham - Central Ontario, Canada
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    iron smelting
    Viking Age material culture
    N. European Pattern Welding
    Design based Artistic Forgings

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  1. I have been waiting a bit (very busy here) to stick my nose in. A couple of general comments, not so much on the actual techique that Lee has suggested, but on artifact tool sets. The Mastermyr find is highly unusual. - It represents what certainly appears to be a *more or less* complete set of both woodworking, and to this discussion, metalworking tools. - The range of metalworking tools is quite wide - ranging from light fine (jewelery?) tools to heavier forging / sledge hammers (hammers run from 400 - 3370 gms) - It includes a good number of 'bits and pieces', so scrap / partially completed / possible 'under repair', both iron and copper alloy materials. - Tenative date for the deposit is roughly 1150 AD Other tool finds tend to be isolated pieces - or collections from burials The problem with a burial collection is that there is no way to tell how complete it is - in terms of representing an actual working set of tools. Did they bury grandpa with * all * his tools - or just a 'representative set'. Where the tools included just 'grandpa's favorites' - or 'give him something, but we're gonna keep the good stuff for ourselves'. I certainly can't remember any of the grave finds containing more than a minimal selection of tools. No collection that specifically resembles a weapon maker's tool selection. And honestly, given the rarity of blacksmith's grave goods, this is hardly surprising! Given the raw expense / value of iron as a material, we should feel lucky we find as much as we do. As has been pointed out by Ric, Mastermyr certainly appears to represent a 'generalist' selection. The original reason just *why* that tool box ended up sunk into a shallow pond is quite unknown. That reason may suggest much about just what got included in the box. To double check, I did go back to my copy of 'The Mastermyr Find' by Arwidsson and Berg. There is nothing in the find that to my eye looks like the required top and bottom fuller set. The design of almost all the hammers is identical, with fairly sharp cross peens (offset to the handle side surface). Number 66 does have a reasonably rounded face, at about 3 cm diameter, curved about 5 mm off flat. Weight is 600 gms, I'd think a bit light for forging. It also is extremely elongated, at over 20 cm long. This really looks pretty much like a modern raising hammer, and given the cook pots included in the find, this does seem to be its original intended use. Number 68 has a wider, but shallower curve to its striking face. It is however, constructed with all the mass to the opposite side of the handle eye. This again most certainly is a dishing hammer. (I use a replica of this tool for that purpose in my own shop). There are a couple of rectangular blocks in the collection. these are generally about 4 x 2 cm cross section, range from about 5 to 18 cm long. All have generally flat end surfaces (May be slightly domed or dished in, but that really appears more from use than purposeful design.) Of course, one of the standards for experimental archaeology is 'Abstinence of Proof - is NOT Proof of Abstinence' I will suggest however that the notion of spring style fullers I would consider unlikely. Do remember the general small size of 'Dark Ages' anvils in the first place. They are taking a big bloom and shaping it down into a rough cube - and that makes the biggest anvil they could make. Norse blacksmithing anvils do tend to be in the size range of 10 x cm blocks, something like 5 - 10 kg total. As someone has pointed out, assistants were most likely on hand. A blacksmith was very unlikely to work in isolation, like so many of us are more or less forced to in the modern world. Another related factor; Consider the small scale of the historic *forges* as well. I've done a bit of work with a re-created Norse style forge. Charcoal piled against a bellows stone using a twin chamber bellows closely based on the two existing illustrations from the time period. Although welding temperatures can certainly be achieved, the effective heat zone is much smaller than what we all are used to. My own experience is no more than about 10 cm at effective working temperatures, more like 7.5 cm worth to welding heat. I certainly have not attempted pattern welding with this equipment. (Was on my research list this year, but at best its looking like late fall before I can even consider getting to this!) As I mentioned to Lee when he first floated this working concept to a few of us - I really do think he may be on to something.
  2. Lee does lurk here, but on a more irregular basis. Allan has given some good basic suggestions. You can't go far wrong with input from Jesus. The short shaft furnace, with a high air volume, is a basic set up many of us have refined over the last years. see some descriptions: http://iron.wlu.edu/ http://leesauder.com/smelting_research.php (those are Lee's collected materials) http://journal.exarc.net/issue-2012-1/ea/if-you-dont-get-any-iron-towards-effective-method-small-iron-smelting-furnaces (article on basic method I wrote - but slanted to living history sites) I personally like Royal Oak. It is not the cheapest. The quality is very high. I find the oak charcoal breaks nicely into suitable 'cubes' and produces less dust and fines. We end up using maple wood charcoal as standard here in Canada. Maple gives good heat, but does tend to splinter a lot on breaking (more dust and fines). Most of us agree the worst choice is 'Cowboy' brand. The quality is uneven, there are a lot of rocks, dirt lumps and even metal pieces sometimes in the bags. (It looks like they are using old rail way wood ties for the source.) Traditional in Japanese furnaces is pine charcoal. Not sure if you can even get that type here in North America. Also check local resturant supply outfits. Sometimes you can purchase large bags intended for use in BBQ places. Your ore will also prove critical to your final results. ??? One note on tuyere angle: The Smeltfest group initially tested for various air insert angles. The 'sweet spot' appears to be between 15 - 25 degrees down angle. Lee likes the shallower 17 down. He also has the best experience and by far the best control over the furnace of all of us. The slightly shallower angle means more room for the bloom to develop, but also means your have to be very careful about slag creation and control via tapping. (Lee has developed and uses a 'continuous tapping' method.) I tend to a slightly deeper 22 down angle. This has proved a bit easier to manage (at least for us here). Again, your ore is going to be important in relationship to the exact angle you select. Natural ores vary considerably in terms of how much slag they can produce. Your air equipment is going to be a factor as well. Too little air volume - and too little air pressure, may result in more errosion of the interior of your furnace = more slag produced as well. Its all a balancing act - there really is not a 'one size fits all' good luck Darrell
  3. A couple of things On Tuyere angles The Smeltfest Group (Primaries Sauder, Williams, McCarthy, Markewitz) undertook a specific series in 2005 to test just this aspect. A number of similar furnaces were constructed, varying the tuyere angle. That is obviously the short form. Refer back to one of Lee's (or one of my own) formal papers if you want all the details on what we *think* is going on inside the furnace. For practical purposes, an tuyere angle of between 15 - 25 downwards angle has proven most effective with these short shaft furnaces. At core this is the balance between doing, recording - and analyzing (!!) Most all reading here are *doing*. I have put together some overall charts of my own experimental work http://www.warehamforge.ca/ironsmelting/smeltvariables.html (only to 2007) http://www.warehamforge.ca/ironsmelting/index.html (at the top there are a set of 'point form main variables', each with images) That web site also has all the data individually from all the smelts so far (although I'm a bit behind on the most recent ones). I did start a larger project attempting to pull in all the data I could find, from individuals undertaking 'Dark Ages' period equipments and methods (c 450 - 1100). Since the explosion of interest in Early Iron, (and my own life, the universe) I have pretty much given up on that project (at least for now). Right now Neil Peterson and I are attempting to get more data collected on all the blooms we have made and have on hand here. Primarily to get accurate weights and undertake very (!!) rough carbon content via simple spark testing. I freely admit the problems with sparking blooms, and my own limits on observations. I remain (pitifully!) behind in the 'bloom to bar' conversion phase. Right now I'm trying to get some data together on loss rates at that step, especially as it relates back to the ore to bloom phase. Oh, yea. Should be making some more actual *objects* out of all this bloomery material too! Darrell
  4. Bryan (and everyone else) since I was implicated... My team here has made some input pressure readings. Honestly using fairly cobbled together instruments. This primarily to counter criticisms (largely from theoretical academic commentators) that all the current work is not 'scientifically rigorous' enough. (But like Lee says 'If you don't get any iron - whatever you have done *has* to be wrong'.) The first thing we tried (cheap and only a relative measure) was a simple U tube with water in it attached to the tuyere side. This gave us some rough ideas - at least between individual smelts. Eventually I got a small guage (off E-bay) that measured 0 - 30 psi range. (The trouble I had was finding something in the right range, at a price I could manage.) Some of the individual smelts in our series here have the input pressures measured. You would have to check through the individual 'smelt data' records one by one - there is no centralized table with all the variables charted from all the experiments. (Neil and I am working on that however - with plus 60 smelts, and so many measurement points, its pretty ugly.) see : http://www.warehamforge.ca/ironsmelting/index.html Overall, the average we recorded for input pressure at the tuyere was 3 - 5 PSI.* We also were using a rough guage for input volume. This consisted (budget again) of a wind surfer's speed guage placed across the input pipe. The volumes were calculated mathmatically from the flow speed. Again not the ideal, and it turned out fatigue in the vanes at the high speeds measured really effected instrument performance with time. I have been using a different method than Lee uses for controlling the input air from the electric blower. (I've managed to purchase one of the same high end blowers he uses by the way). You can see the sliding plate gate (from a dust collection system) located just at the exit from the blower. So I'm limiting the amount of air into the entire downstream system. (Lee uses a moveable plate just in front of the tuyere set up, venting off excess air.) Both of us have some rough calibrations on these valves that let us have some rough approximation of the air we are providing to the overall system. Mine is marked (very rough approximations!) of 100's of litres / minute (based on earlier measurements). Lee's (was) marked in fractions of total possible (1/4 - 1/2 ...) My smelting partner, Neil Peterson, is driving an experimental series investigating Viking Age glass bead making furnaces. (Even *less* archaeology than for iron smelting furnaces!). He has deeper pockets than I certainly do (!) and has recently invested in a multi input data recorder system. Along with high temperature probes, he has purchased some modules that will record pressure, and a better quality vane type air speed (so volume) instrument. We still have to assemble the fittings and run some tests, but we have good hopes for better (more consistant) measurements into the future. You may have gathered from all that - my thrust here has been to researching possible historic *process* - with less concentration on *product*. I have to agree with what Mark has said : That historic air delivery systems may not result in the most efficient utilization of ore = not the best quality blooms. You most certainly can *make* iron in lower air systems (and this most certainly was the method for much of human made iron production). What many researchers miss is the second stage - of bloom to bar. What you may gain in simplicity from ore to bloom is competely lost by the extra labour / materials converting a lacy bloom into a working bar. Lee has much better experience / notes / observations about this aspect. Ok Lee and Skip experimented and documented and then introduced to all the concept of high volume air = better ore to bloom conversion, both in terms of size and density. (Historic note, look at the impact of water powered systems circa 800 - 1100 AD in Europe - pretty much the same thing!) Although some experimenters have produced measurements of input air pressures, I am uncertain that anyone has attempted to measure pressures inside the actual furnace itself. As Mark as mentioned, delivery air needs to be considered in terms of not only *volume* but also in terms of *pressure*. This is why people attempting to use rotory blacksmith's forge blowers as air sources often have less than the best results. Those equipments produce a large volume - but at virtually no pressure. The air simply does not penetrate through the tuyere diameter into the charcoal mass. Increasing the diameter of the tuyere might assist this. Using multiple tuyeres would certainly help (and both methods are seen in historic systems.) But in actual fact, none of us need to really worry so much about absolute pressure measurements, or even with measuring air volume. The best 'working' measurement is via charcoal consumption. Rate of charcoal consumption is also the effect of internal temperature and size of the effective heat zone. Bigger and hotter = faster charcoal burning. Most of us are working on some variation of the 'Sauder System', what historically I would call the 'short shaft' furnace. Most typically our working furnaces have an internal diameter of closer to 10 - 12 inches. This is quite important when discussing measurements and working methods. As you have seen, there is a dance between ore / charcoal / furnace / air. My own experience is that there is no *absolute* 'perfect' furnace. Any basic design will have to be modified based on changes to those four primary elements. Hematite will not produce the same results, even in identical furnaces and method, as the bog iron ore analog I typically use here. I'm (educated?) guessing that any attempt to modify the internal gas pressure in what is a very rough and simple furnace will prove far more effort than effective in result. Past experience has proved the simplest way to effect the reaction ability of a furnace is just to increase the total stack height. (Nice example there, Mark gave 40 inches as his ideal stack height - I usually build for closer to 24 - 30 inches. My standard furnace diameter is larger, rarely below 10 inches, to his reported 8 inch minimum. I know we are working with quite different ore types, and maybe charcoal as well.) There are just too many other variables (things that can, and often do, go wrong!) I'd be interested in what results you come up with / records generated. Darrell
  5. hmm I must start by staying I run coal here as my primary, although I do have a good number of propane forges of various builds and sizes. I think the best you can do is get some rough estimate at best. The individual burners make more difference for fuel consumpton and top temperature as anything else. Heat loss from the containment is a function of surface (square) while your interior space is volume (cube). This suggests the effect of heat lost is reduced for larger forges? Just as important might be the time to temperature of the metal itself. Penetration into the centre is another volume over surface ratio - but this time working the opposite direction (volume increasing far faster than the surface area where the heat can be absorbed). You may have the number of BTU available, but its just going to take a lot longer to get that bloom mass hot enough. Consumption per hour may be fixed, but heating time is greatly increased. You run 10 lb tanks? I'm using 40 lb ones here and need three of them to keep an ample supply on hand. Admittedly my forges are home builts (and thus not the best in terms of burn effeciency!). I get about 12 - 14 hours out of a single 40 lb, giving me just into a yellow, with my two burner (with about a 12 x 12 x 5 inch interior). Delivery pressure on that one set about 6 psi (although that number might not mean much specifically) Be interested in any actual numbers you generate. I do have a digital pyrometer here, next time I fire the propane forge (today a day off for me). I will get some accurate temperature numbers on my unit for comparison. They have been talking about starting a user carbon tax here in Ontario - and in Canada generally. Of course right now this is too vague to really mean much, but it would likely increase my costs at each purchase. The blacksmithing coal we use here already is shipped by truck from the USA (Penn. / WV). Right now it runs roughly $50 CDN for a single 75 lb bag (closer to $35 with bulk purchase). I had looked into *carbon* use for my full time operation here in Ontario back in 2008, when the concept of a carbon user tax was first proposed here: http://warehamforgeblog.blogspot.ca/2008/07/carbon-and-forge.html The currious thing was that *coal* turned out to be the *smallest* carbon foot use - at least based on my use. (I freely admit that this did not take into account production or transport carbon generation.) Darrell
  6. Historic (European) furnaces are found made of many materials: slabs of stone large stones used like bricks smaller stones as filler in poor quality clay pure clay grass sod stacked like a volcano hole dug into the ground along a natural bank Modern Iron Smelters have used: plain clay brick chimey liner tile various combinations of refactory materials / heavy steel pipe The construction of the furnace needs to: endure high temperature for the course of the smelt hold in the reactive gasses There are two general principles you can base the furnace on - a *thin* wall - that radiates off excess temperature to keep the wall from melting Sauder, Flue Tyle - http://www.warehamforge.ca/ironsmelting/FlueTyle/index.html - a thick wall - that edures the errosion of high temperature Markewitz, Econo-Norse - http://www.warehamforge.ca/ironsmelting/EconoNorse/index.html One note on stone: You ideally want an igneous type of rock: https://en.wikipedia.org/wiki/Igneous_rock The softer sedimentary types will be destroyed by the temperatures inside these furnaces.
  7. Jared: Nice little photo essay on your experiment. I especially like the spark test images. Charcoal size is in fact critical. Aim for 'walnut to pea' size. (The standard is breaking through a 1" grid, then sieve out the small fines via a 1/4" grid). I would say that the irregular carbon content over a single metal 'puck' is pretty much normal as well. (This goes with full bloomery iron furnaces as well.) A few numbers might help assess just what you got: - Furnace interior diameter and height - Depth below tuyere - Tuyere angle - Metal input - Metal output Its hard to say exactly how your test turned out - without knowing your input and especially output numbers. The location of your formed puck seems about right however. The depth this forms below the air entry point is effected by tuyere angle and air blast (both volume and pressure). Do be aware that a 'virgin' furnace almost always run a bit strange the first firing. Individual builds tend to 'burn in' to some kind of comfortable base shape with multiple firings. I realize you ended up breaking the furnace, but something to consider into the future. I will mention that to my eye, the walls seem a bit on the thin side. How quickly did you get in there to pull the resulting puck out? There is slag formation in an Aristotle furnace, and this very quickly cools and hardens - and pretty much locks any puck formed into the bottom of the furnace. Your mention of sccoping out remaining charcoal is the method I would advise. Once the last bar is added, you should be keeping it covered with charcoal as it drops, but pretty much letting the charcoal burn down at the same time. It is a bit of a trick (practice!) knowing how much to bleed the air flow off as the charcoal volume reduces. What you are attempting to do is keep the area around the formed puck at roughly the same temperature up to the point you pull the puck out. If you don't have a hooked rod, make one up. A short 3/8 - 1/2 long hook is small enough to work down inside the hot furnace, but big enough to latch on to the edge of the white hot metal puck. Remember to pull *straight up* when you hook out your formed puck. (I have seen many students lever sideways against the top of the furnace - this almost always results in tearing the upper part of the furnace apart.) I typically run 700 - 800 gm input and get roughly 500 - 600 output. This can vary a lot with several runs in a row, with metal 'lost' in the first run or two suddenly 'showing up' with a much larger puck than expected on run three or four. But the cool thing is you got a good result - and on your first run of the furnace!
  8. Boy - did this get warped fast! My original commentary on the 'living body' thing was an attempt to ** dismiss ** the concept, with the purely practical reasons why. As 'fake-lore' goes, it has amazing staying power. (The topic had come up in another, quite unrelated, newsgroup I participate.) I will point out however, the technical truth that a 5% salt solution might be effective (sometimes). And pose a question, as this thread is concerned with history: How do you produce a consistent salt solution - in ancient times? 1) Not every location has access to mineral salt. (consider the cost / significance of salt in history) 2) Urine is far from consistent! (consider the difference between production after a hot forge day - against production after that mentioned '9 Guinness') 3) Sea water is far from consistent. (consider the effects of wind, currents, recent weather, local fresh water sources) Blood, on the other hand, *is* extremely consistent, at least in terms of salt content. The donor requires a fairly small variation to maintain life at all. I will leave it to the more experienced blade makers here to discuss the actual effective application of 5% salt solution as a possible quenching medium. I fully expect the response will be 'Depends what you are making - and what metal alloy you use.' The 'point to North' thing is given in Alex Bealers' book on Blacksmithing. As it was available as a cheap re-print for a long while (at least here in Canada) I suspect many reading may have a copy. (it was a common gift item for decades). For the younger readers, you should remember that for a good long while there was very little available as a resource for starting blacksmiths. As poor (and often inaccurate) as Bealer's book is - before Jack Andrews published 'Edge of the Anvil' in the late 1970's, there was almost nothing at all. I honestly have not made any effort to trace that specific bit of fantasy back any further. I would * highly * recommend Prof. Foil's extensive web publication 'Iron, Steel, and Swords' http://www.tf.uni-kiel.de/matwis/amat/iss/index.html Helmut Foil is a material scientist, he covers the basics of the science in some detail - but goes on to cover a huge amount of technical, historical (and just plain interesting) material - over some 1000 pages of linked text and illustrations.
  9. Friends: I thought this might be of some interest to the regular readers (excerpt from a posting to my own blog) : In his blog post, Prof. Föl discusses a number of historic receipts for quenching solutions. He provides the original texts, translations, plus interpretations of the (often hidden) meanings for the individual components. Not too curiously, carefully manipulated urine figures prominently in many of the historic 'secrets'. In my own return communication to him, I had mentioned my belief that the original source for the 'quenched in a living slave' concept was from an Early Medieval Arabic text. His research into historic sources has pointed to this idea itself being nothing more than another piece of the 'fake-lore'! Fortunately, I see my original post on 'Quenched in the Living Body' does not give this specific (incorrect) source. I had just referred to the very real practical problems that makes the whole idea plain stupid.
  10. That first suggestion is information by Lee Sauder. Lee is more or less responsible (along with is smelt partner Skip Williams) for starting the 'early iron' movement here in North America. You will also find some technique guides plus extensive documentation on my own web site : http://www.warehamforge.ca/ironsmelting I would also recommend you look at the tutorials available from Jesus Hernandez at : http://jhbladesmith.com/ All three of us are active on this forum Although somewhat dated now, there is some basic information available on the original Early Iron web site : http://www.geocities.ws/earlyirongroup/ As for single purpose publications - there basically are none. The closest you will come - and highly recommended, is Lee's DVD 'Ore to Axe' This documents the entire process he has established, from material preparation, furnace building, through the smelt itself. Available from Lee : http://www.leesauder.com/smelting_video.php There are a couple of specialist research volumes that a few of us in the core experimental group have found valuable. These are collections of related academic papers, and not really directly 'how to do' guides. They are also not easily come by... Darrell PS - A word of caution: There is an ideal combination of ore / fuel / furnace design / physical process. Change one, you almost always have to change other elements for true success. The basic system of a small scale direct process bloomery will not always produce identical results - most especially dependant on the type of ore you utilize. Part of the adventure has to lay in the trials (and expected error!), and there is no substitute for just getting out there and trying it! (Be extra careful of single attempt illustrations seen in places like YouTube!!)
  11. Tim Your frame of reference is 900 - 1000 AD, and I believe the physical location is in the Dublin region? You should take a look at the extensive archaeology from the Woods Quay excavations in Dublin. Admittedly primarily Norse rather than Irish - but given the interactions between the two groups, the close match in time and place, it would be hard to find better references. Most of the hard archaeology I have seen indicates the use of ground mounted forges. The only illustration we have from Scandinavia from the same time shows a table mounted fire however. I've put up a number of articles on my blog referring to Norse forges, bellows construction: Shape of Forges in Early History Viking Age Sand Table Forge
  12. Justin: you also said : "First run, tuyere the diameter of a pencil, 45deg about 3 inches above floor" The Smeltfest team initially ran Aristotle furnaces for over a week - something like 5 -6 different builds, over 35 individual firings. As with the full sized iron smelting furnaces, the 'magic number' for the tuyere down angle is * 22.5 *. You can get good results from 15 to 25 down - but you should stay in that range. Your 45 degrees is so steep that you would be placing the air blast right on top of the developing metal 'puck' - and slag is all you would likely be your result. You would have most likely just cut up any developing metal deposit. Did you see those bright 'burning iron' sparks at the top of your furnace? (Bad sign!) Those who try to warp this process via using higher temperature refractories are putting too much work / expense / (theory) into the build. The intent her is a fast, easy to build furnace - which should be considered 'semi disposable'. With the small size, my own experience is that you are far more likely just to break the thing when extracting the metal puck - than suffer significant erosion to the furnace walls. Some erosion *is* to be expected (remember what I said about 'virgin' furnaces. Simple potter's clay, or cobb mixes (chopped organics) work extremely well. Cheap and easy. You mention a furnace at 10 - 12 inches tall - but with the tuyere point set at 4 inches above the base. That gives you only a reaction column of perhaps as little as 6 inches. Just barely enough. Especially when combined with the next factor... You mention using pine as your charcoal. The Aristotle system was developed and tested for hardwood charcoal. And also for charcoal sized at walnut to pea sized pieces (as I mentioned). Different types of charcoal can act quite differently in any smelting related furnace. With the Aristotle, the miniature size means any margins for error are also quite small. Softwoods are going to burn faster - and collapse the working column quicker. You would certainly have to make some modifications to the entire working system to account for this. As Mark has suggested - each working system varies from a theoretical base template. Each variation from the exact details given in any description means also a potential variation in the results. If you copied *all* the method exactly, then you *might* get expected results as given. Do remember that these smelting and hearth based furnaces are only recently 're-discovered' - there is still a large amount of objective experimentation required to realistically understand and control all the variables involved. (Compare this with learning to forge weld - only at least an order of magnitude more complex!) I have personally run / observed the Aristotle system run over at least 20 + different furnace builds - and maybe 75 + individual firings. (bet Mark has done a big pile of these as well). Every time you build a new furnace - there is almost always other variables that need to be adjusted before you get some desired result. If you wanted to consider any of the smelting processes 'science' - it would certainly be 'rocket science'. The *process* has to be considered as big an objective as the physical *product*. Otherwise you might as well just purchase modern alloy from your steel supplier... Enjoy the experience! Darrell
  13. Justin: First - there are a couple of guides to the Aristotle method, done up individually by those of us involved in the original 'Smeltfest' research group that worked up Skip Williams' concept furnace. My guide is posted at : http://www.warehamforge.ca/ironsmelting/Aristotle-HO.pdf On my blog at : http://warehamforgeblog.blogspot.ca/2012/03/demonstrating-aristotle-furnace.html One description you left out - How high was your furnace? You say you followed Skips original description. Did you use the shredded horse manure with clay (possible sand) mix? Normally what should happen is that your first use burns in the furnace to some stable shape internally. It is not unusual to get a lot more slag your first cycle. It should stabilize after that firing. As you indicate - charcoal can be surprisingly important in the small scale of the Aristotle. You do indicate that you adjusted for correct (walnut) size the second time around. Did you screen out the dust / fines ? (Nothing larger than pea sized ideally) What brand of charcoal / type? A lot of us have experienced problems with cheaper brands (Cowboy brand especially, but there is one brand made of tropical cut and slash stuff that is also inconsistent.) The big one - air flow / burn times. It may be that using a blacksmtih type blower (that is a crank blower you mention?) may pose a problem. You need not only *volume* but also a certain *pressure*. My own experience is that crank blowers may produce volume, but they often have little force to the air flow - and given the small size of the normal inlet tyuere to an Aristotle - the air kind of 'bounces off' the tyuere. You need to watch the *rate* of consumption. Burn rate should be roughly 200 gms / 4 - 5 minutes. For those metrically challenged, that is roughly a standard coffee can measure. Remember that the internal layout (the distance of the base level below the tuyere entry point) is largely what will control carbon absorbed by the growing 'puck'. Each individual furnace is a bit different (and a brand new furnace always gives different results until it stabilizes inside). Once you can effectively get the source bars to effectively melt and re-deposit into a mass, you can expect to tweek that base level to start modifying carbon. You must remember that any working with bloomery type materials (either full iron smelting or hearth modification) is more an art than a science! If you are expecting a single 'cook book' method - you are certainly not going to get the single use method to specific product situation that many blade makers have been expecting...
  14. " I am not recommending this process to anyone ..it is dirty and a lot of work..and may only work with some ores. " I wanted to pipe in here. I've maybe worked with more ore types than most others reading here, primarily because there is no naturally occurring iron ore in my local region - due to geography. Cerainly, * any * natural ore will vary considerably in potential iron content, oxide type, silica combination, dynamic impurities, structural form. One of the source 'ores' I had access to for a while was processed hematite asi fine particle blasting grit. I have worked with this stuff at least 5 + times. I know both Antoine Marcel and Jesus Hernandez have used this material with success as well. On a guess Yan - you are using either hematite or 'iron sand' as your ore? My own experience is that the small particle size of the hematite grit tends to create a metallic iron particle size that also is quite fine. Because of this, temperature control is critical. The iron will very rapidly absorb * too much * carbon. Unless you are very careful, you end up with cast iron. As I understand it, this absorbtion is a surface area effect. Those small starting particles just have a lot of surface area compared to volume. Your images of the results of this smelt certainly look like my own results sometimes - with this fine material at least. The iron produced (if everything is going well) tends to be a crumbly texture, looking much like dampened dark brown sugar. This also tends to be a higher carbon content iron as well. The image you provided of the (potentially) forgeable iron bloom certainly looks the same to my eye as my own results ( http://www.warehamforge.ca/ironsmelting/smeltfest06/report03-06.html ) And yes - I certainly have gotten identical cast iron formed below the slag bowl. One key in your own comment: "...may only work with some ores." For any given ore - there will be * one * ideal design of furnace. The problem here may be in attempting to utilize a single static furnace layout - then attempting * that * to dictate the process (and expectation of results). My consideration of ancient furnaces has caused me to appreciate the basic wisdom of a clay construction for the furnace. This material functions well, especially when modifications of mix using various proportions of sand / addition of organic materials is undertaken. This construction is relatively fast, simple and cheap. The furnaces can be fairly durable under normal operations, especially if a little care is taken with the construction - and especially the extraction method used. More importantly, it is relatively simple to modify the base design of the furnace (stack height) - or simple enough to just build a whole new furnace body (Two or three bags of powdered clay and a couple of hours!) When you examine the archaeology, one thing is commonly seen at larger scale, long term use iron smelting sites. There is often two or three 'unique' furnaces, commonly that show often only single firings. Then there are a whole pile of escentially identical furnances, usually with more durable construction and showing multiple uses. Iron smelting was located most commonly at the site of the ore body. Furnaces were then adapted from a theoretical template to suite the exact combination of ore (and likely charcoal) available at that location. It also needs to be constantly remembered that the historic objective of a direct process bloomery furnace was dead soft * easy to forge * iron. Meaning no or next to no carbon content. As many of the 'old hands' will tell you - bloomery iron making is more an art than a science!
  15. Scott et All One of the problems is of definitions - and just who sets the terms of reference. If you define 'Iron Age' as 'marking the use of iron as material' - then the true Iron Age runs from at least about 1000 BC in Northern Europe. One of the other definition problems is that mainland Europeans / British / Scandinavians all see the frame work of their own past marked by different events. So much of what us English speakers have access to is from Britain. The line between 'before the Celts' and after this invasion is fuzzy at best, and does appear to also mark the transition from a primary Bronze Age into the early Iron Age. The Roman period has sharp lines for initial start and theoretical end. Then there is another fuzzy period around the 'Saxon Shores', when the 'Germanic' Angles and Saxons are invading and colonizing. Complicating this is the whole very modern concept of national boarders. I mean, does a person living in North west France about 200 AD part of 'French' or 'Celtic' or 'Gallish' culture? (Or maybe even some weird mix of Roman plus all of the above?) Part of a big problem for me is the whole concept of the 'Viking Age', which is defined by two British only events : Lindesfarne in 783 and (usually) the Norman invasion of 1066. Some argument at least can be made for an end to the true Viking Age some place about 1000 - 1100, with the growth of centralized kingdoms and gradual adoption of a more feudal structure. The notion that the Scandinavian culture sprung to life fully formed overnight is obviously unrealistic! I was a bit surprised when I managed my one trip to Denmark that there they break the lines at 'Iron Age' to 1000 AD and then 'Medieval', running afterword. (I guess I should not have been!). North Germany and Denmark into Scandinavia was relatively untouched by Roman culture (quite unlike the rest of Europe). Some histories out of mainland Europe will mark 'Migration Period', which usually is some (again fuzzy) time 'post Roman - pre Medieval'. This is at least a bit better than the older seen line of 'Roman to Medieval', given as the 'Dark Ages'. (Honesly, I'm never quite sure just when that is supposed to cover - at least in terms of end dates.) As your interest is clearly on * object *, your best bet might be just digging into the archaeological record. Not a simple task, as you are unlikely to find a single point reference that is going to help you. Its going to be a tedious task of checking dates and find locations. One of the huge problem is one of simple survival of iron objects. The Celts of La Tene are a primary * Iron Age * culture. But what do we find? Bronze objects! Iron swords corroded and locked into decorative bronze scabbards, with only rare x-rays giving any clue at all about physical structure of the blades. Complicating this is the whole modern tendency to apply our current 'best technical practice' backwards. 'Steel' means something quite different when applied as a descriptor by an archaeologist to an Iron Age blade than it means to a modern bladesmith. Original bloomery iron materials most often had little or no carbon - and have a quite different physical structure from our modern alloys. It is clear when you look at primary archaeological reports that our current practices of heat treating were only being developed and more randomly applied through the 'Late Iron Age'. Darrell (ok - I'd guess a big chunk of those commenting here already know this stuff...) Hoping that one of our friends from NW Europe might add their (better) knowledge!
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