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M. Eversberg II




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PostPosted: Mon 22 Mar, 2010 1:10 pm    Post subject: The revitalization of mediveal iron working?         Reply with quote

On more than one occasion here and on other websites I've seen mention of a 12th century (?) "enhancement" to the collective whole of iron working in medieval Europe. This lead to a vastly larger quantity of iron being produced in weapon and armor quality, and more iron for other products as well. This lead to more and more fighting men getting heavier equipment for less, and apparently lead to the all-famous sword becoming much more easily obtained. What exactly caused this progression?

I know sometime around this event larger smelting furnaces were being constructed, which would allow you to put in more iron at a given time, and thus receive a larger bloom per run. Since from what I understand you have to put the furnace back together each time you do a run, this would certainly save some time. But what would make larger furnaces needed? If there was a "backlog" or ore before this period, then I'm sure they would just have built larger furnaces to compensate. Was there a boom in the quantity of ore known about and or harvested that lead to this? Were mines becoming more efficient due to mining technology advances? Was there simply more labor (larger population, more efficient farming) that could be put into mining and processing? Was it advances in water power that enabled billows large enough to pump enough air into these furnaces?

Before this period, were simple iron goods like farm equipment (iron plough and those cooking pots come to mind) just that much more expensive? I've read some things about the knights of Charlemagne needing to sell their entire lands to own a handful of military goods, from horse to helm and sword and mail; a value worth a small fortune. I cannot venture to guess what simple but iron intensive things like cooking pots and farm tools would have cost, unless they're very thin and perhaps not work/material intensive (were pots cast?) I'm often told that it was the value of the raw iron, not the wage, that really drove the prices of a given good, though with some things (say military-spec equipment) I'd imagine the tiny labor pool could have been a major contributor; lots of knights, not so many sword-smiths.

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Chris Kelson





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PostPosted: Mon 22 Mar, 2010 4:21 pm    Post subject:         Reply with quote

I'm pretty certain that such 'simple' household ironwares just didn't exist until iron production had dramatically increased. There are of course alternatives to iron, for instance wooden mouldboards on ploughs, wooden spades with (at least by the 14th C) the edge occasionally re-enforced with iron and I'm pretty sure I've come across mention of copper and bronze cookware.
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Jared Smith




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PostPosted: Mon 22 Mar, 2010 8:31 pm    Post subject:         Reply with quote

I don't claim to know the exact answers to your questions. There were several developments that spread around 12th and 13th century. I would say that on the whole, iron production began to become something of an organized industry with trade specialists. Water power was harnessed to drive blast furnaces and more industrial type forging machinery. Needle mills and other specialty production can be dated to around 13th century. Steel wire drawing mills are known to have been in existence near late 14th century. Coal mining is not considered to have been popular in that era yet, but charcoal production was itself a specialty trade.

This is mostly later time period, but you can probably appreciate the scale of development within just a couple of centuries, and the long history of the Wealden area. http://www.solarnavigator.net/history/wealden_iron_industry.htm

Also check this one for 8th century forward known archeology. http://ads.ahds.ac.uk/catalogue/adsdata/cbare...003001.pdf

There is a good survey of 13th century English iron production, but right now I don't know where to locate it. The interesting finding in it was that audits indicated that cutting tool grade steel was imported from Germany in 13th century era.

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Jeroen Zuiderwijk
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PostPosted: Tue 23 Mar, 2010 1:10 am    Post subject:         Reply with quote

The introduction of the blast furnace, which is more suitable for working at larger scale. As you said, a bloomery is an interrupted process. But also, if a bloom gets too big, it becomes more difficult to handle (not impossible, just difficult). Cast iron can be cast into the size ingot that you want, and then refined.

Waterpower became used not just to power the bellows, but also to pump water out of quaries such as in Sweden, powering large grinding wheels as well as large hammers.

Overal industrialization, such as f.e. in Solingen. There you have good ore, lots of forrests for fuel and lots of streams for water power all on the same location. Because of this Solingen became a major iron producer as I understand it.

And what would have helped is an increase in wealth in general. If agriculture becomes more efficient and productive, that leads to more wealth and more people being able to do other things then grow food and spend on other things than food, such as ironware.

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PostPosted: Tue 23 Mar, 2010 2:24 am    Post subject:         Reply with quote

Chris Kelson wrote:
I'm pretty certain that such 'simple' household ironwares just didn't exist until iron production had dramatically increased. There are of course alternatives to iron, for instance wooden mouldboards on ploughs, wooden spades with (at least by the 14th C) the edge occasionally re-enforced with iron and I'm pretty sure I've come across mention of copper and bronze cookware.
To my knowledge, bronze or copper has always been a lot more expensive compared to iron from the time iron became in common use. So bronze or copper cookware would have been very expensive luxury items, certainly with the amount of metal that goes into them. The cheap alternative to metal cooking wear is pottery. AFAIK they were used until well after the medieval period.
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M. Eversberg II




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PostPosted: Tue 23 Mar, 2010 6:04 am    Post subject:         Reply with quote

So the iron melting blast furnace was what allowed iron industries to flourish? I suppose with that you could get bars of iron (or plates) in almost any size, though you'd have to reduce them before you could forge them since the carbon's going to be really high. Was this a specialist industry as well? Or would I, the product maker (say a blade, or a sickle) likely have to reduce it myself? I was under the impression that, throughout the middle ages and up until the 18th or 19th century, most iron/steel goods were worked -up- from wrought and not "down" from pig iron.

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Jeroen Zuiderwijk
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PostPosted: Tue 23 Mar, 2010 8:10 am    Post subject:         Reply with quote

M. Eversberg II wrote:
So the iron melting blast furnace was what allowed iron industries to flourish? I suppose with that you could get bars of iron (or plates) in almost any size, though you'd have to reduce them before you could forge them since the carbon's going to be really high. Was this a specialist industry as well?

It was probably a specialized industry as well. Unfortunately, I don't know all the details in steel production development in Europe. I only have a vague overview with a lot of gaps in knowledge.

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Or would I, the product maker (say a blade, or a sickle) likely have to reduce it myself? I was under the impression that, throughout the middle ages and up until the 18th or 19th century, most iron/steel goods were worked -up- from wrought and not "down" from pig iron.

There are a lot of different ways to turn pig iron into workable steel or wrought. The method you're thinking of is the Bessemer process. This involves blasting oxygen through liquid pig iron. This was introduced in the mid 19th century. I don't know if and when other methods were in use. One method is by carefully forging the pig iron in a finery forge, and loosing carbon through decarburization. Another method is puddling, which involves melting the iron in a slag bath, and stiring it to extract the carbon (possibly not introduced until the mid 18th century, though more primitive variants may have existed earlier). And of course there's also combining bloomery and pig iron in crucibles to produce crucible steel. There's many more ways to produce steel, which makes the history of steel making very complex.

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Thom R.




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PostPosted: Tue 23 Mar, 2010 10:13 am    Post subject:         Reply with quote

Its a bit of the chicken and egg economic interrelation of supply and demand but there does seem to be an increase in higher quality iron ore supply in the 12th c., Many of the richer deposits in present day Germany, especially in Saxony - for whatever reason - geological, political, etc - don't seem to have been discovered or developed until the 12th century. It is also the 12th century that we see the blast furnace develop in Central Europe. This is a major technological development for smelting iron ores. There were also other technological advances involving water wheels, wheel driven hammers for crushing ores, and wheel driven pumping systems that allowed drainage of mines which facilitated getting at more ore. So there does appear to have been a mining/technology reason for increasing supply of iron.
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Jared Smith




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PostPosted: Tue 23 Mar, 2010 1:31 pm    Post subject:         Reply with quote

Thom R. wrote:
Its a bit of the chicken and egg economic interrelation of supply and demand but there does seem to be an increase in higher quality iron ore supply in the 12th c., Many of the richer deposits in present day Germany, especially in Saxony - for whatever reason - geological, political, etc - don't seem to have been discovered or developed until the 12th century.


I am uncertain what the actual situation was. The same "Germanic" approximate regions seem to be known for active specialty in metal related industries from B.C. era until present. (There is a lapse of knowledge in migration era, but very little to prove if the industry completely collapsed at that time.) Fairly good quality iron seems to have been shown in some artifacts dating back to B.C. era. (Even pattern welded, twisted spits, or core rods, suitable for what we think of in the center of a "Viking" pattern welded sword. Some spits found in a Greek temple to Apollo fountain are even 1.5% carbon wootz strands twisted and welded with dissimilar steel. I do not know of someone who can replicate that welding feat today as chemical wootz simulations crumble at welding heat.) I personally attribute the successes of some early Celtic works (Halstatt cultures and others) in that region to be at least partly a result of discovering the quality of local ores, and also having neighboring regions that also specialized in metalworking.

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Thom R.




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PostPosted: Tue 23 Mar, 2010 3:15 pm    Post subject:         Reply with quote

yes my point is the supply of high quality ores, derived from magnetite and hematite, increased in great part due to improved mining technologies in Europe in the 12th c. . that was true also of copper and silver mining. in general mining tech made some big leaps forward in the 12th c. yes there were other factors too. (political, social, economic).
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M. Eversberg II




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PostPosted: Tue 23 Mar, 2010 7:14 pm    Post subject:         Reply with quote

Jeroen, I was actually thinking of the second process you mention, where I forge work it from a hard bar of pig iron and reduce it in my forge fire until much less carbon remains; the Bessemer process completely skipped my mind.

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PostPosted: Tue 06 Apr, 2010 3:13 pm    Post subject:         Reply with quote

Below are a couple of excerpts from “ARCHAEOMETALLURGY OF LOMBARD SWORDS From artifacts to a history of craftsmanship”, VASCO LA SALVIA. It is available as a free download, and I recommend it to those who are interested in this subject area.

It is not mentioned in this article, but a handful of the 11th-13th century era German style furnaces’ geometries functioned as efficient natural draft designs. Part of the increase in iron production resulted from two aspects of the improved furnaces; an average 3X capacity increase in throughput, and higher quality resulting blooms that are believed to have only needed one reheat and reforging before sale as ready to use iron.

“The decline and the eventual dissolution of Roman-imperial mining teams did not in fact produce a parallel disappearance of the related mining techniques; on the contrary, due to the dispersion within the territory of the artisans once active in the traditional mining centres (19) such techniques were maintained without substantial changes until the introduction of extractive machines which led to the technical progress typical of the European mining-boom from 1460 to 1530 (20).”

“It is clear that, during this given period, it is difficult to determine a uniformity in ironmaking, either by evaluating the situation of the two differing traditions (the Roman and the German one) or by analyzing the forms that this metallurgical activity took.

However, there is a crucial point which can be regarded as the main contribution of this period to the metallurgy of iron, and it is apparently of German origin: the spread of the slag-pit furnace. Once a “simple” sunken hearth was equipped with walls the low shaft furnace was created. This changed not only the capacity of the furnace, which was increased, but also the fuel’s loading system which was now loaded in a vertical direction. Moreover, since charcoal and ore remained longer in the reducing atmosphere of the shaft, poorer ores could also be smelted, even if not much below the 55% of Fe2O3, and better slag creation conditions were achieved. A deep hearth was maintained even if it did not take any part in the reducing process and was transformed into the slag container. This slag-pit furnace, possibly of remote Celtic origin, dominated iron metallurgy during a period of about five centuries in those countries never occupied by the Romans. This was the progressive model, which through the further development of the classic shaft furnace, can be regarded as a predecessor of the blast furnace (60). With regard to the production capacity of these slag-pit furnaces, experimental archaeology provides some results. Presumably, one iron bloom weighed circa 2.5 KGs;
100 KGs of bloomery slag is the discard-material from the smelting of about 18-30 KGs of iron. In the case of a production unit of five slag-pit furnaces, which produce around 20 KGs of slag, the rough output can be estimated as 9-15 KGs of iron ready for blacksmithing after reheating and reforging (61).”

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Jean Henri Chandler




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PostPosted: Wed 07 Apr, 2010 7:36 am    Post subject:         Reply with quote

It was the Cistercian monks spreading the technology of the overshot water wheel and the windmill which lead to automated triphammers and automated bellows which allowed for a sorrt of mass production of iron, this lead to many more and larger bloomery forges being made in many regions of Europe, particularly in Northern Italy (notably Milan) certain parts of Central and Northern Germany and Bohemia, and Catalonia, and a few other places.

http://en.wikipedia.org/wiki/Cistercians
http://en.wikipedia.org/wiki/Overshot_water_wheel#Overshot_wheel
http://en.wikipedia.org/wiki/Overshot_water_w...val_Europe

Quote:
Cistercian monasteries, in particular, made extensive use of water wheels to power watermills of many kinds. An early example of a very large waterwheel is the still extant wheel at the early 13th century Real Monasterio de Nuestra Senora de Rueda, a Cistercian monastery in the Aragon region of Spain. Grist mills (for corn) were undoubtedly the most common, but there were also sawmills, fulling mills and mills to fulfill many other labor-intensive tasks. The water wheel remained competitive with the steam engine well into the Industrial Revolution.


http://en.wikipedia.org/wiki/Catalan_forge#History

Quote:
Early bloomeries were relatively small, smelting less than 1 kg of iron with each firing. Medieval Europe saw the construction of progressively larger bloomeries, leveling off at around 15 kg on average, though exceptions did exist. The use of waterwheels to power the bellows allowed the bloomery to become larger and hotter; European average bloom sizes quickly rose to 300 kg, where they leveled off through the demise of the bloomery. Water powered bellows and larger bloomeries also increased the heat to the point where the iron could melt; this was not considered desirable because it allowed carbon to diffuse into the molten iron, producing unworkable pig iron. Molten iron was not desirable until the advent of the blast furnace.


http://en.wikipedia.org/wiki/Triphammer#Medieval_Europe

Quote:
Water-powered and mechanised trip hammers reappeared in medieval Europe by the 12th century. Their use was described in medieval written sources of Styria (in modern-day Austria), written in 1135 and another in 1175 AD.[20] Both texts mentioned the use of vertical stamp mills for ore-crushing.[20] Medieval French sources of the years 1116 and 1249 both record the use of mechanised trip hammers used in the forging of wrought iron.[20] Medieval European trip hammers by the 15th century were most often in the shape of the vertical pestle stamp-mill, although they employed more frequent use of the vertical waterwheel than earlier Chinese versions (which often used the horizontal waterwheel).[8] The well-known Renaissance artist and inventor Leonardo de Vinci often sketched trip hammers for use in forges and even file-cutting machinery, those of the vertical pestle stamp-mill type.[10]


Europeans apparently also began converting bloomery forges into blast furnaces in the 11th-12th Century in Sweden, Catalonia, Switzerland and Central Germany:
http://en.wikipedia.org/wiki/Blast_furnace#Medieval_Europe

Quote:
An improved bloomery, named the Catalan forge, was invented in Catalonia, Spain during the 8th century. Instead of using natural draught, air was pumped in by bellows, resulting in better quality iron and an increased capacity. This pumping of airstream in with bellows is known as cold blast, and it increases the fuel efficiency of the bloomery and improves yield. The Catalan forges can also be built bigger than natural draught bloomeries.

Modern experimental archaeology and history re-enactment has shown there is only a very short step from Catalan forge to the true blast furnace, where the iron is gained as pig iron in liquid phase. (snip)
The oldest known blast furnaces in the West were built in Dürstel in Switzerland, the Märkische Sauerland in Germany, and at Lapphyttan in Sweden where the complex was active between 1150 and 1350.[10] At Noraskog in the Swedish county of Järnboås there have also been found traces of blast furnaces dated even earlier, possibly to around 1100.[11] These early blast furnaces, like the Chinese examples, were very inefficient compared to those used today. The iron from the Lapphyttan complex was used to produce balls of wrought iron known as osmonds, and these were traded internationally – a possible reference occurs in a treaty with Novgorod from 1203 and several certain references in accounts of English customs from the 1250s and 1320s. Other furnaces of the 13th to 15th centuries have been identified in Westphalia.[12]

Knowledge of certain technological advances was transmitted as a result of the General Chapter of the Cistercian monks. This may have included the blast furnace, as the Cistercians are known to have been skilled metallurgists.[13] According to Jean Gimpel, their high level of industrial technology facilitated the diffusion of new techniques: "Every monastery had a model factory, often as large as the church and only several feet away, and waterpower drove the machinery of the various industries located on its floor." Iron ore deposits were often donated to the monks along with forges to extract the iron, and within time surpluses were being offered for sale. The Cistercians became the leading iron producers in Champagne, France, from the mid-13th century to the 17th century,[14] also using the phosphate-rich slag from their furnaces as an agricultural fertilizer.[15]


Ingots of partially processed wrought iron began to be widely traded throughout Europe in the early Middle Ages:

http://en.wikipedia.org/wiki/Osmond_iron


A trip hammer


A 12th Century Cistercian water mill


J

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Jean Henri Chandler




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PostPosted: Wed 07 Apr, 2010 7:55 am    Post subject:         Reply with quote

Jared Smith wrote:
Moreover, since charcoal and ore remained longer in the reducing atmosphere of the shaft, poorer ores could also be smelted, even if not much below the 55% of Fe2O3, and better slag creation conditions were achieved.


I think this is an important point, from what I have read the most important factor was the improvements in the smelting techniques, largely due to new mechanical technologies, that allowed so much more good quality iron to be produced, not so much a vastly superior supply of ore. With efficient enough forges etc., the ore doesn't matter that much.

J

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M. Eversberg II




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PostPosted: Wed 14 Apr, 2010 12:13 am    Post subject:         Reply with quote

Thanks for the information. I think one day I'll have to find a way to give smelting by hand a go just to see what that's like.

M.

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