Melting steel in an enclosed clay container (NOT CASTING)

[Matthias 0311]

Hello everyone, this is my first post after browsing for a few days looking for an answer to my question. I couldn't really find the answer I was looking for, but perhaps I didn't look hard enough. I work at a living heritage museum called Furnace Town, outside of Snow Hill, MD, where in the early 1800's, people smelted iron from bog ore they dug up out of the bottom of the nearby creek. I do demos for people regularly, especially for school field trips, showing them how blacksmiths back then worked and dressed and the tools they used, etc. etc. After years of doing this, I have accumulated buckets of steel (we mostly use mild and carbon steel nowadays) that are too small to use for anything and I have wanted for a while to melt it down and form ingots out of them to then hammer into bars and then whatever it is I want to make from that. I know that this is the foundry/casting forum but casting steel is the last thing I want to do. I don't have the want or desire to mess with molten steel in a tiny crucible cup and try to pour it into a mold and end up spilling it onto the floor or have it melt a body part off, etc. Instead, what I wanted to do was what people here did with the small bits of iron they couldn't work with anymore, which was to dig up a bucket of clay which is common around here, add things like dried shredded grasses and wood ash and envelope the small bits of iron in a clay ball. They would then either make a clay/brick enclosure, fill it with charcoal and place the clay ball into the center of it or dig a hole in the ground, fill it with charcoal and again, place the clay ball into the center of it. The hole in the ground would then have either more clay or more likely, mud laid over the charcoal to enclose it. Then they would use a small bellows to pump air into the side of the enclosure, or down a trench that was dug next to the hole for supposedly at least half a day to make sure the iron melted together. This idea just seems a lot safer than pouring molten iron/steel into a mold so myself and an older blacksmith wanted to get other's opinions on the matter seeing as how there are not any classes on the topic anywhere nearby. Any of the self-proclaimed curmudgeons on here have any advice on things like the amount of ash/shredded grass to mix with the clay, or how thick to make the ball surrounding the metal, or how much charcoal to use for this (I was thinking about a couple of buckets of charcoal at least). Thanks for any advice and I have posted some pictures of the old furnace and the blacksmith shop in my profile for those interested.

I'm pretty sure that people here back then also melted iron in a crucible and poured it into molds, but there hasn't been any evidence of this discovered so far and most of the records of this place, which were stored in the courthouse in Snow Hill, were lost in a fire during the turn of the 20th century, so things like census reports, tax information, and whatnot were all lost. There are also old pictures of people sitting atop of the furnace working on the pipe bellow as well as standing on top of humongous charcoal mounds that were covered with mud. Once they get scanned I will upload those as well as anything else I can scrounge up. Thanks again for any advice.

[ThomasPowers]

May I commend to your attention "Steelmaking before Bessemer Vol II Crucible steel."  I'd be AMAZED if they melted steel and did anything but just cast it in an ingot at that time period.   For one thing cast steel has poor properties and required a lot of forging to refine the grain.  It's main virtue is that it lacks the ferrous silicate slag and uneven carbon content.  Forge welding odd bits of iron/steel together was a common and easy task at that time.  Your description of what they were doing sounds a lot more like making blister steel or the oroshigane process in Japan.

[Lou L]

While dangerous, it would definitely make for a great learning process if you work your way to it carefully and thoughtfully.  I personally have no knowledge base to help but I have an insight.  If you intend to do this as an intellectual endeavor then I commend you and wish you a safe learning process.  However, I would guess that the cost of doing this just in casting equipment and safety gear would far outstrip the cost of buying the steel you need.  

If you are just trying to be frugal you could find a metal artist who may seriously love a stockpile of randomly shaped scraps.

 

Lou

[ThomasPowers]

I was thinking of the apprentices who had to weld used horseshoe nails into usable sizes.

Definitely today this would be a "look I just spent US$50 in charcoal and two days time to make a $1 piece of steel!"

But like smelting iron ore it can be fun to do just for the experience!.

[Matthias 0311]

Oh this is definitely not a money saving venture, we were just curious about what it would be like and to see how the possible ingot would turn out and if it were workable at all. When it comes to it being dangerous, this whole trade is dangerous. That's what I tell people when they ask me questions such as, "Isn't this dangerous?", "Won't you get black lung?", and "Why aren't you wearing gloves?" It just always seemed a little too dangerous to try to cast any type of metal really, let alone steel, hence why we never wanted to do that. There is a bunch of protective equipment, from safety glasses to face shields and welding helmets, aprons and large welding gloves and jackets, although I wasn't quite sure any of it could withstand molten steel exploding out from the clay ball/enclosure if it indeed would ever do that. Thanks by the way on looking into Steelmaking before Bessemer, lots of good info about that and you're right about it sounding like blister steel. There are archaeology students from a nearby college who do digs here every now and then and I was told that between their professor and an older blacksmith here that could have been a possibility that they might have tried something like what I was referring to, although again, like I said, they haven't unearthed any actual proof of it as of yet.

[Lou L]

It sounds to me like your crew knows how to have a good time!  I applaud your willingness to bring history alive.  Please keep us updated on your process.  I'm sure that, with all the knowledge on this forum, we will amount to some help...and your investigation is right up our alley.

[CMS3900]

Welcome to IFI Matthias.

I might be reading what your trying to do the wrong way, but it sounds to me like it's along the lines of Ric Furrer's Wootz process with different materials. He takes a clay vessel that has been fired, adds his ingredients, puts a fired clay top on it and seals it, and then heats it until everything is together. Check out "Secrets of the Viking Sword" if you get a chance, it might be on youtube. He goes over the process in it.

I have yet to get to Furnace Town, but have heard it is really nice. Only about 2 hours away and I can never make it down there.

[ThomasPowers]

Now Dr Feuerbach's Thesis on Crucible Steel in Central Asia (it wasn't all wootz you know!) has a lot of info on how the process was being done there which was to melt in a sealed container and let gool and then break the "puck" out and recycle the container remains as grog when making more of them...

Steelmaking before Bessemer Vol 1 Blister Steel has a lot of good info on the Blister Steel process

And of course there is Theophilus'  Divers Arts (1120 A.D.) talking about case hardening files by "greasing them and wrapping them in leather and encasing the leather with well kneaded clay and then heating the clay'd bundle and breaking it open and dropping into water"  

Also please remember that a lot of blacksmiths do not know much about the history of the craft prior to the 1850's...so a good idea to vet your expert sources!

[Lou L]

Thomas, I'm not sure if you watch much YouTube but a machinist who runs a channel called Clickspring is currently rebuilding the Antikythera mechanism from X-ray scans of the original.  He is doing the research and trying to use period methods wherever it is realistic to do so.  He made his own files using the same resource.  He also came up with a strong theory about how they may have layed out the gears.  His argument is powerful and may be a legitimate addition to scholarship on the subject.  I think you would enjoy watching his process.

Lou

[ThomasPowers]

Since I have slow rural internet connectivity I don't watch much video; but I may have to track those down.   The interesting thing to me is the device does NOT appear to be the result of starting tech but  rather from mature tech; where are all the ones leading up to it?  Are there lumps of verdigris languishing in museum sub basements awaiting CAT scans?    Any good works in Ancient Greek on the use of gearing for such things?

[Lou L]

I'm not aware of any.  Sadly, most Greek knowledge was lost to the fire in Alexandria.  What was left was sold to Turkish and Muslim kings who knew it was worth more than the gold, silver and silk they desired in Constantinople.  The Eastern Roman Empire sold their libraries.  It could likey be found in Arabic.  I imagine some of the texts are still sitting in a monastery somewhere but they have never seen the light of day. Truth be told, in my Attic Greek classes they always focused on Homer, Plato, the historians, and the New Testament (easy Greek we hoped was on the test).  Hated translating Thucydides!

JHCC would know more for sure though.

[JHCC]

No, that's about right. 

As for earlier forms of the technology, my own hypothesis is that the Antikythera was preserved by being lost, and that other examples of similar ancient technology ended up getting melted down and used for other things. 

[Lou L]

I actually did some searching and found a few books by scholars who collected all of the references to technology and building they could find from Greek and Latin texts.  There was some interesting stuff on metal work and files but, sadly, it was all just references and limited descriptions of processes.  The loss of knowledge was great.

[ThomasPowers]

I assume you are familiar with the Berlin Foundry Cup?