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Dan Hurtado

Where to begin?

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Guys,

I'm looking to try my hand at steel making. But it is (to put it mildly), daunting.

I've read numerous threads within the Bloomers and Buttons section here and watched countless YouTube videos on the topic. They are all very informative and helpful, but it seems that many of them start at a knowledge base which is still a distant spec on my horizon.

 

I've got about 70lbs of Florida bog ore and I've made a setup to produce my own hardwood charcoal. I was planning to roast the ore in the drum while making the charcoal, then build a bloomery. I'm not looking to turn out huge quantities, just enough high-ish Carbon steel to experiment making blades with.

 

I guess what I'm looking for is some repeatable process data: stack & tuyere dimensions, charcoal & ore weights, air CFM rates, burn times, etc.

 

I realize this is somewhat like asking, "Hey guys, how do I make a knife?" or "What's this whole 'brain-surgery' thing about?" I'm just looking for a way to speed up the trial and error process.

 

Thanks!!

- Dan Hurtado

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Along with the video, most of what I've ever managed to write down is also an the website, here:

 

http://www.leesauder.com/smelting_research.php

 

It's good to be realistic, but don't be daunted. The sooner you get the mistakes out of the way, the sooner you'll get iron!

 

Good luck!

 

Lee

Edited by Lee Sauder

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Dan

 

there are almost three separate aspects to your request - so here is some (unasked for?) advice.

 

It seems almost anyone will put something on to YouTUBE. If they know what they are doing or (more often) not. As an information source, this makes it almost useless. Compounded by the truth that few people actually * explain * what they are actually doing there. Multiplied by the poor records or measurements many groups illustrated even bother with in the first place.

(The number of * failed * iron smelts seen on YouTUBE *greatly * outnumbers the effective ones seen)

 

You obviously have access to the internet. Google search 'iron smelt' and you may notice something. A couple of names come up in excess : Lee Sauder / Darrell Markewitz / Jesus Hernadez

All three of us provide extensive documentation on our process, and significantly, records of past work. Lee alone is pushing 200 individual smelts he has personally undertaken (!)

 

Both Lee and I have 'basic method' documents available for download. Jesus has an excellent video tutorial available.

 

This is not YouTube. A successful bloomery iron smelt takes at least two full days of work to accomplish (one for build and prep, then roughly 4 - 6 hours plus on the actual smelt process). Nothing you can distill down usefully into a ten minute clip.

 

Two effective teaching furnaces described:

Lee's 'Flue Tyle' - http://www.warehamforge.ca/ironsmelting/FlueTyle/index.html

Darrell's 'Econo Norse' - http://www.warehamforge.ca/ironsmelting/EconoNorse/index.html

 

Effective bloomery iron smelting is as much * Art as Science *.

A well written guide by an experienced teacher can certainly help you avoid some of the worst mistakes. Anyone who tells you that this is a cook book process just does not know what they are talking about.

 

This is a long adventure - welcome!

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In addition to the excellent advice already given by people who know FAR more than me, I will suggest not roasting your ore in the charcoal kiln. There is a real risk of over-roasting it that way, actually kind of pre-smelting it into something that will be harder to reduce in the end. A simple wood fire for an hour or two is more than enough. There would be way too much reduction going on in the coaling barrel.

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Guys,

Thank you so much for all the great information. As you have said, much of what's online is somewhat anecdotal and it's difficult for a novice to fill in the gaps.

 

Since iron ore in Florida is about as common as hen's teeth, I'm grateful for anything that will help accelerate the learning curve.

 

We didn't pick an easy hobby, did we?

Thanks again,

Dan

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Lee, you have made several modifications to your stack furnaces over the years. What is the best design you have come up with to date?

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My advice would be to get to somewhere where someone who knows their onions is smelting and watch / help them.

 

Its much much easier to start with a proven model and then deviate away from that into your own direction than to start everything from scratch.

however with your own ore its all gonna be individual.

 

It is satisfying and challenging and frustrating and fun!!

 

and trust your gut instincts, it's very easy to get bogged down by knowing to much and cerebralising the whole process

 

and keep records.

 

and don't drink 8% belgian beer during the smelt , it can really mess the whole thing up.......

 

I have found it very useful having a smelting partner to cross flow information with , that really helps with working out what is wrong/ right...

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My advice would be to get to somewhere where someone who knows their onions is smelting and watch / help them.

 

Its much much easier to start with a proven model and then deviate away from that into your own direction than to start everything from scratch.

however with your own ore its all gonna be individual.

 

It is satisfying and challenging and frustrating and fun!!

 

and trust your gut instincts, it's very easy to get bogged down by knowing to much and cerebralising the whole process

 

and keep records.

 

and don't drink 8% belgian beer during the smelt , it can really mess the whole thing up.......

 

I have found it very useful having a smelting partner to cross flow information with , that really helps with working out what is wrong/ right...

 

Absolutely!

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Good general advise from Owen!

(especially the beer part - ask Mikey)

 

- Use a proven design (look for those who have had repeated successful smelts)

- Make sure you have a blower that proves both * volume * and * pressure * (see Lee's descriptions)

 

- Having a separate team ready for the consolidation hammering is a good idea. Your smelt workers are going to be tired (especially those undertaking extraction!). As Lee (wisely) says : 'its never going to be as hot as when you first pull the bloom'.

 

Ore quality and characteristics is the single largest variable. You can do everything else perfect, but if you ore is below about 50 % iron content - you are not likely to get anything (but slag).

 

Darrell

Edited by Darrell @ warehamforge.ca

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Thanks guys!

One final question. (Well, that's a lie. This is FAR from my final question)

Any advice on smelting furnace materials? Firebrick? Kitty Litter?

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One of the easiest and cheapest is equal part by volume EPK pottery clay (comes from Forida, btw!), sharp white sand, and shredded peat moss. Mix well dry and add just enough water to make it into a dryish dough, kneading thoroughly, mold into balls about the size of a softball, and store in a sealed plastic bucket. After a the clay and moss have had time to let the moisture even out, use the balls to build your stack. Hard firebrick can work, but doesn't contribute to the slag and is kind of expensive. Kitty litter is Bentonite clay, which is not the most heat-stable. In other words, it cracks more than most.

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As I mentioned, there is a dance between ore (as the lead) and furnace details. Playing the tune is construction materials on melody and charcoal type sometimes improvising.

 

Powered potters clay is cheap and very easy to work with - and can be purchased as known types.

Local clay is considerably more work (unless you are one of the lucky ones) and usually will have quite specific (likely unknown) properties.

You can make your own decision if digging, hauling, drying, breaking, cleaning then re-mixing a local clay is worth the roughly $10 - 15 a bag of powdered clay costs.

 

Working with clay obviously gives you the most flexibility in terms of design. (Making a cylinder using rectangular bricks is sometimes not the easiest.

Remember that the air blast, so the burn pattern in the furnace will be some variation on a *spherical' volume. You make a square or rectangular furnace and there are going to be corners that are not going to burn / contribute to the reactions. (Japanese Tatara aside, but there the system uses multiple air points to get around the physics.)

 

Like everything else, there is a knack to working with hand mixed clay.

Lee / Owens advise of mixing up your clay balls and leaving them to relax is excellent (time / space / manpower allowing)

 

At this point I don't think any of the successful, multiple smelt workers are using a straight clay (??)

 

Sand in the mix reduces the way wall material expands when it heats to operation temperature.

A high sand mix does require considerably more effort on the build. It also requires much more careful drying / baking before the furnace is used.

The result however, with the care needed, is most certainly a more durable furnace.

This is the mix that Lee is using, and has had an individual furnace re-used dozens of times.

 

Organics added will do three things

Pieces remaining in the outer layer of wall act to bind the whole structure together. This action tends to limit potential cracking, and hold the walls together even if cracks form.

Organics with hollow cross section (ie - straw) allow some place for the expanding steam to go, steam produced when the water in the clay heats. The massive increase in volume as water flashes to steam is the primary source of cracking of the clay walls. (Obviously very careful / long duration drying limits this available water remaining in the walls)

Pieces remaining in the inner layer of wall will eventually burn away with the high temperatures of an operating furnace. This in effect leaves air spaces, which are insulators. The gross effect is to help limit the loss / spread of heat into the exterior surface of the furnace. (This at least in theory, honestly I doubt anyone has actually tested for this ??)

 

Obviously differing organic additives will perform differently:

- We tested 'peat moss' - purchased locally as spaugam moss for gardening. The long pieces soaked up excessive water and held it, making mixing a bit of a pain (hard to get consistent mix). Then the drying became a real problem. In the end we got excessive wall cracking - there was just too much water being held by the mix.

It might be that what you get locally as 'peat moss' might vary an extreme amount - region to region. (Sorry Alan)

- We have had extremely good results with shredded, dry horse manure. Get last year's pucks, rub them between your palms. What you end up with are very dry lengths of grass, usually about 5 - 10 mm long. Added to clay, these pieces act just like fiberglass bits in car repair 'bondo'. (I learned this technique from Micheal Nissen in Denmark.)

- Our old stand by here is chopped dry straw. Cut the pieces to 5 - 10 cm long with a hatchet or machette. Straw (rather than hay) has the hollow core mentioned above. The net effect is just like adding rebar to concrete. It does make hand mixing a bit of an effort.

 

Learning from Lee, the normal mix used here at 'Viking Age Central' (Wareham Ontario) is a rough mix by volume :

1/3 powdered clay / 1/3 course sand / 1/3 organic material

Often we will use a higher fire temperature clay (like the EPK suggested) for the part of the furnace around the tuyere level (which suffers the highest temperatures). I have noticed any particular problem mixing different clay types in one furnace.

 

We are undertaking more experimental archaeology here than production smelting here. For that reason, we are constantly changing details on furnace construction (so building a *lot* of individual furnaces!). To date we have only used one furnace for a total of five smelt events, the average is closer to two smelts per furnace before we build a different model.

 

After seeing a whole lot of furnaces built, I would suggest the most important factor is :

Take your time and use care in the build - this pays back with less cracking and more durability

The single biggest error people make is not making sure the individual balls / blocks of mixed clay are well fused to each other as you build up the walls. Cracks are almost always along the joint lines of the individual blocks as added.

 

Darrell

see

www.warehamforge.ca/ironsmelting

for images of a whole lot of differing 'Short Shaft' furnaces

 

(yes - this will end up today's blog post...)

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