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Quote:Tony, that's a question that remains unaswered as yet. I've asked a number of blacksmiths (including you) and the best I got so far is that twisted metal shafts might be more heat-resistant, implying that such twisted plumbatae were used as incendiary devices.

Good thought; never considered that before.
The twisting adds strength to the shaft. Plumbata seem to have been made from assorted scrap iron, an thin band of metal can be made stronger (resist bending) by twisting it into a spiral. What you are basicly doing is making a cylinder from a strip. The flat strip is easy to bend/fold, once twisted, it will resist bending, as the whole thing will act as a cylinder the size of the widest part of the strip. So a strip of metal 1 mm thick and 10 mm wide will act like a cylinder about 8 mm across. You can do that test in any woodfire, using a strip of iron, two pliers and a pair of thick gloves for safety.
Thanks for the added info Robert.
To add to Robert’s post, the July/August 2015 edition of Minerva magazine (distributed free to those who attended the Greek and Roman Armour Day on Monday) contains an article by David Sim on this very point. Noting that the shanks of some arrow-heads, javelins and plumbatae had been cold twisted and doubtful that this had been done for decorative purposes, he tested the effect of cold and hot twisting on the rigidity of iron. He explains that cold twisting involves twisting the iron at room temperature, whereas hot twisting involves heating the iron to red heat (usually 720ºC), twisting it and then either quenching it in cold water or allowing it to cool in air. He cut a number of samples from a single bar of wrought iron and cold or hot twisted them through 360º or 720º. He found that further twisting was not possible as cold twisted samples fractured at 724º. He then subjected the samples to a three-point bend test. This consisted of supporting the samples between two cylindrical bars and dropping a square bar with a rounded end on to them through a hollow square tube. The distance of the drop and the weight of the drop bar were the same in each case. The extent to which the samples bent was then measured. An untwisted bar was also tested as a control. The degree of bending suffered by each sample was as follows:

Untwisted bar: 6.9 mm
Cold twisted 360º: 6.0 mm
Cold twisted 720º: 5.0 mm
Hot twisted 360º: 9.5 mm
Hot twisted 720º: 11.9 mm

Thus, cold twisting increases the rigidity of the iron and the greater the degree of twisting the greater the rigidity, whereas hot twisting has precisely the reverse effect. The conclusion he draws from this is that, when twists were added when the metal was cold, the increased rigidity rendered the weapon more effective in penetrating its target.
Michael,

Thank you very much for that information. Apparently David Sim is recently doing very intersting research about plumbatae!

I've taken a look at my database and as it turns out, only very few plumbatae have twisted shanks. Of the grand total (163 published remains), 63.8% has a smooth shank, only 5.5% has a twisted shank, and of 29.4% I have no information (in the case of 10.4% due to the find being incomplete). If the 57 unprovenanced items known to me are included, these figures chance to 71.3%, 5.4& and 22.2% respectively.

The question rising from that low amount would perhaps best be answered by looking at the plumbata as a 'fast and dirty' weapon (perhaps best compared to the slingshot), where in most cases not much care was put in perfection. All speculation of course.
Could it not suggest, perhaps, two things:

a. The nature of the enemy or target being faced? If you do not need burning plumbata why waste the twisted shanks unnecessarily?

b. There was no local facility or fuel (perhaps) to make a fire hot enough to twist the shanks?
Quote:Could it not suggest, perhaps, two things:
a. The nature of the enemy or target being faced? If you do not need burning plumbata why waste the twisted shanks unnecessarily?
b. There was no local facility or fuel (perhaps) to make a fire hot enough to twist the shanks?

Sounds logical.
It's been some time since my last update, and a few more plumbatae have been added to the database:

31 from Serbia
29 from Britain
15 from Austria
15 from Slovenia (up from 14)
14 from France
12 from Italy (up from 8)
9 from Croatia (up from 8)
9 from Hungary
7 from Germany
7 from Switzerland
5 from Georgia/Abchasia
4 from Rumania (up from 3)
3 from Bulgaria
3 from Greece
2 from Liechtenstein
2 from The Netherlands
1 from Belgium
1 from Slovakia
68 from doubtful or unprovenanced origins

Total 237
As usual an update is accompanied by a new map.

[attachment=12349]
Over the past 6 months, a few more plumbatae have been added to the database:

31 from Serbia
30 from Britain (up from 29)
15 from Austria
15 from Slovenia
14 from France
12 from Italy
9 from Croatia
9 from Hungary
7 from Germany
7 from Switzerland
5 from Georgia/Abchasia
4 from Rumania
3 from Bulgaria
3 from Greece
2 from Liechtenstein
2 from The Netherlands
1 from Belgium
1 from Slovakia
72 from doubtful or unprovenanced origins (up from 68)

Total 242

One beautiful example is from the (unknown to me) Vatevi Collection (Bulgaria), another from the usual internet sale.

[attachment=12901]
The usual additions to the plumbata database:
Currently there are 171 published finds:

31 from Serbia
30 from Britain
15 from Austria
15 from Slovenia
14 from France
12 from Italy
10 from Hungary (up from 9)
9 from Croatia
7 from Germany
7 from Switzerland
5 from Georgia/Abchasia
4 from Rumania
3 from Bulgaria
3 from Greece
2 from Liechtenstein
2 from The Netherlands
1 from Belgium
1 from Slovakia
74 from doubtful or unprovenanced origins (up from 72)

Total 245

One new (unfortunately unprovenanced) example is from the Balkans, location unknown. What seems to be a torqued shaft and an unusually four-bladed head. Length is 169mm, weight just 55 grams.

[attachment=13417] [attachment=13418] [attachment=13419] [attachment=13420]
Thanks again Robert Smile very different, it looks like it has a square shaft before twisting. How do you think it is attached to the shaft ? tang or socket. it is a good length as well Cry ouch! if you are hit with one Cool Thanks again.
Regards Brennivs Big Grin
(11-24-2016, 11:43 PM)brennivs - tony drake Wrote: [ -> ]How do you think it is attached to the shaft ? tang or socket.

As it widens slightly toward the lead, my guess would be socket.
Thank you very much Robert most useful  Wink
REgards Brennivs Big Grin
A study I did earlier this week:

[attachment=13495]
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