How DENSE are you? Measuring Blooms

20 years

90 personal bloomery iron smelts

Ya, I have a few blooms kicking around...

Like about 30 

(not counting smaller pieces, blooms now rendered down into bars)

During the early years, working with Lee Sauder and others at the annual Smeltfest workshops, typically individual smelts were in the 45 kg range, which in turn resulted in blooms at 8 + kg. 

Tests done here in Wareham (where accessing ore was a problem) more typically ran 25 to 30 kg ore, with resulting blooms averaging between 2 - 5 kg. This primarily because we figured if you could make a medium sized bloom, with more ore and time you could certainly make a larger one. 

Another reason was simple handling of the blooms themselves. There is a physical limit to how much impact force (largely untrained!) workers can apply with hand sledge hammers. Even historically, once blooms got much over about 5 - 8 kg, they were cut up into smaller chunks to allow effective compaction into the finished iron bars.

So 

Something I was told at the 2008 'Iron in Thy' symposium always has annoyed me. As it did the other working participants sitting around that table :

'Modern experimenters are unable to produce iron blooms of similar quality to those made by the ancient iron masters'

At the time, I certainly felt still fairly new to bloomery iron smelting, to the point I just felt I was staring to get some handle on the methods. (I would have been at numbers 33 - 35 at that event). In 2008, I did not feel I had enough direct experience, and certainly not any hard numbers, to refute that sweeping statement.

Obviously, even a dozen years later, that statement (from a well known archaeo-metallurgist) still sticks in my craw.

Generally, all the blooms produced here at Wareham are 'finished' to the same level, which does help make some comparisons valid. Given the small working team, with normally only myself as having any blacksmithing experience (1) we hammer work any bloom through only the heat available at extraction. This involves knocking off any clinging slag, then very rough compaction to force loose exterior into the core. As temperatures are rapidly dropping while this is happening, there is rarely any actual welding taking place, more mechanically pressing out larger voids and forcing out still fluid slag. 

Starting in 2012, there was a 30 ton hydraulic press available at Wareham (modified log splitter). In some cases, after the initial hand hammering, blooms were rushed to the workshop and the mass was given several compressions, then cut via the press.

So over the last two weeks, I have pulled out the blooms on hand here.

Each was re-weighed (to differing methods, depending on overall size)

Three different containers were used for volume by water displacement. 

There certainly will be accuracy limits determined by the simple equipment used. Water measurements at best accurate to 5 ml within 1000 ml. Larger blooms, over 6 gm, weighed with a scale +/- 5 gm

The overall intent here is to compare these measurements against densities published for some artifact blooms, one problem being that sample size is considerably smaller.

Preliminary results :

Wrought Iron (solid bar) = density of 7.75 gm/cc (2)

Bloom Average (28 samples) = density of 6.28

This actually compares very favourably to artifact blooms, at least the few I have found with descriptions of density. I will be trying to contact some specific museums to see if they can provide numbers on their artifacts.

1) Neil Peterson has been slowly increasing his skill and knowledge of working blooms specifically. Neil has been coming up and undertaking afternoon workshop sessions were he has been taking pieces in the 500 - 800 gm range and compacting these down into finished working bars. I should be noted that this still is different than sledge hammer work - Striking is it's own separate skill set (and one that I also have rarely done!)

2) https://www.engineeringtoolbox.com/metal-alloys-densities-d_50.html

Recent Workings : 'Look at the BONES...'

 

'Look at all the BONES...' 

Addition of Animal bones into a Bloomery Iron Smelt
  June 20, 2020

Smelt Team:
Neil Peterson, Rey Cogswell
Smelt Master : Darrell Markewitz

ABSTRACT

    Several recent papers have suggested the presence of small fragments of bone sometimes found within the debris fields related to bloomery iron smelting point to a possible 'ritual' practice, even so far as proposing a functional impact on iron bloom quality. How might the physical process within a complete iron making sequence effect the ability of bone to endure, and thus remain to be recovered archaeologically? A typical 'short shaft' furnace will be constructed and operated through to bloom extraction on a clean working surface. Both bone pieces and meat containing bone of several animal types will be added, before, during, at at the final stage of the smelting process. Afterwards, the debris field will be examined in detail to determine what remains of the bones.

 

This is another lengthy report, more a draft for a possible paper later :

Part One : Build and Smelt

 Additional : Smelt Images

    Part Two : Excavation and Evaluation

  " It is important that this experiment makes no attempts to suggest ‘why’ Norse smelt masters may have chosen to, or even if they ever did, add bone pieces into a working furnace. Extreme care must be taken in any attempt to apply ritual practice from other cultures, remote in time, geography, working methods, and especially radically differing world views.
    " The fairly consistent destruction of any bones added during charcoal charging does suggest that it is unlikely to recover archaeologically anything beyond the uncommon and smallest traces of added bones. The only likely situations where bone has much chance of leaving traces after being added to a functioning bloomery iron furnace :

• Meat containing bone, but only if added at the very end of the smelting sequence.
• Bones placed on the base layer of the furnace, before the smelt actually starts."

10 Lines - 'Golden Age...'

 

Looking back, we all realized it had been a golden age :
 

As we had moved southward into those wide open plains, it was clear the animals had never seen a human hunter before, the large game falling to our spears so easily we could choose only the best cuts of meat.
 

The floods came so predictably every spring, our new crops harvested to surplus every year, allowing some to not even farm at all, learning instead to shape clay and metals beyond merely functional, into intricate art works.
 

Copper begat bronze which begat iron, as our leaders became kings, organizing the building of stone monuments to rival the works of the gods themselves.
 

Our roads spanned the landscape, with our iron clad Legions enforcing the Pax of Empire and allowing ease of communication, trade and travel for our Citizens.
 

Using our water powered mills we built stout ships while we looked to the sun and stars, braving with confidence the open ocean to spread our rule using Guns, Germs and Steel over what we now knew was a sphere.
 

The universe itself became a clockwork toy, our mechanisms breaking forever our bondage to the land, crowding us into cities, into factories, while the chosen few lived a life of ease.
 

First through steam, and the power of electricity, our machines drove Empires on which the sun never set, allowing the Educated Gentlemen to explore and catalogue and ponder.
 

Dreams shown on flickering screens drove aspirations of material wealth beyond the wildest imaginings of even a generation before, while education and medicine became the norm as the ‘have nots’ strove to become just as wealthy as the ‘haves’.
 

We broke beyond the bounds of the Earth itself, watching on tiny screens, each holding more information than had even existed in our parent’s youth, while fully expecting stores stocked high with cheap goods from all corners of the globe and foods wildly beyond natural seasons or limits of geography.

10 Lines - Load Out

 

The gear had hung in the backroom closet, since the move up country, long years ago.
 

A personal load out, intended to support a sudden flight from urban target into some vague rural destination.
 

It had been packed against potential need, a reflection of now distant times and once dreaded circumstances.
 

’I’ve got it if I ever need it, and if I ever do need it, I’m going to really need it.’
 

’Besides’, with a smile, ‘You know the deal : If I have a thing, I’ll never actually need the thing…’
 

At least dry tested after hushed late night phone calls from friends of friends of associates, warning of bright green tracks on sweeping screens.
 

Now, not so much forgotten, but more like some kind of integrated talisman; not much of a guarantee, but at least some kind of preparation.
 

But the years churned by, ‘the bones turning old, stiff and sore, the forgotten gear from a forgotten war’ (to paraphrase a line).
 

‘Lessons’, some just imagined, from situations two generations back, put together in bits and pieces, hanging ready, while the world changed, circumstance changed - and physical ability faded away.
 

In the end, the carefully packed equipment, and the knowledge it represented, turning into a home for mice.

Readers : This is more intensely personal than these have been up to this point. Although you can see the shift into topics pressing on my mind of late. 

The image was gathered over the internet, my gear not exactly as seen there. Missing is the shell dressing to upper left shoulder strap, compact binocular case the lower right strap. There is a machete scabbard, then the mess tin carrier on the left belt (holding a folding stove and two pouch meals as well), with a small personal first aid kit, then grenade pouch (compass matches, snare wire, basic fishing kit) to the right. The rear 'fanny' gas mask pouch holds a plastic tarp sheet and more boil in bag meals, plus odds and ends.