Medieval bronze casting

For stories, poems, pictures

Moderator: Moderators

guthrie
Absolute Wizard
Posts: 2341
Joined: Sun Aug 14, 2005 8:54 pm
Location: Polmont-Edinburgh

Medieval bronze casting

Postby guthrie » Mon Nov 15, 2010 9:15 pm

This has been a fairly successful summer for my 4 year old project to actually learn to do bronze casting the old fashioned way.
I got my bellows powered furnace working properly and reliably, new and better crucibles, and learnt how to make the mould material for the casting.

First, the crucibles. I had some made by a potter, using graphite flake supplied by James Durran and Son.
Image

Clay mixed with graphtie flake, about 1/3 by volume graphite. State of the art for the late 15th century, although most surviving examples from the 16th century onwards. Usually made in Bavaria and shipped all over Europe and even to the America's. They'll take going from a red hot furnace at 1200C to room temp without cracking or shattering, although repeated rapid cool downs does lead to cracking. The molten metal also runs out of them very easily. All you need to have to make them is graphite, clay and an experienced potter.

Secondly, a lost wax horse harness pendant, in bronze. It is a bit rough, and reflects the fact that i don't have a huge amount of skill in carving the wax or making the mould with it:
Image
Nevertheless, it only took about 4 hours from start to finish, carving the wax, putting the moulding clay around it, melting it out, drying the clay, and melting the metal, a leaded bronze similar to that which was common in the late medieval period.

Finally, the mould material. Clay and horse dung and some sand, made up by hand and feel. Too much organics and clay and it doesn't hold together well, too much clay and it can crack and is also a bit hard to work. I have examined quite a number of medieval clay and sand moulds, and mine look like some of them, but it is clear that the mould recipe varied depending on the job they were doing.
So here is a side view of one of my buckle moulds with a buckle in it. Note the blackened (reducing, ie carbon rich ) interior:
Image

So that is it, I now have everything to be able to do authentic medieval bronze casting in the middle of a field. And I have done, at Lanark festival of history.


Buy my book about Alchemy in Medieval and Tudor England:
http://www.newcurioshop.com/alchemy-med ... r-england/

Velund
Posts: 38
Joined: Mon Mar 01, 2010 8:15 pm
Contact:

Re: Medieval bronze casting

Postby Velund » Mon Nov 15, 2010 10:26 pm

Really cool!
We never tried doing like this though we are quite experienced casters, I'd say.


Welcome to http://armourandcastings.com/!
Loads of casting, armor and leather stuff for reenactors.

guthrie
Absolute Wizard
Posts: 2341
Joined: Sun Aug 14, 2005 8:54 pm
Location: Polmont-Edinburgh

Re: Medieval bronze casting

Postby guthrie » Mon Nov 15, 2010 11:10 pm

Once you know what you are doing it isn't too hard. But getting to know what you are doing takes maybe 3 weeks practise and a fair bit of research.


Buy my book about Alchemy in Medieval and Tudor England:
http://www.newcurioshop.com/alchemy-med ... r-england/

User avatar
gregory23b
Absolute Wizard
Posts: 2923
Joined: Sun Jul 17, 2005 9:46 pm
Location: Gyppeswyk, Suffolk

Re: Medieval bronze casting

Postby gregory23b » Mon Nov 15, 2010 11:19 pm

Excellent mate.

Next you will be doing a thurible, as per Theophilus.


middle english dictionary

Isabela on G23b "...somehow more approachable in real life"

http://medievalcolours.blogspot.com

"I know my place." Alice the Huswyf

guthrie
Absolute Wizard
Posts: 2341
Joined: Sun Aug 14, 2005 8:54 pm
Location: Polmont-Edinburgh

Re: Medieval bronze casting

Postby guthrie » Mon Nov 15, 2010 11:42 pm

Thats a point. I also managed to cast a couple of useful sized pestles when at Kentwell, but they are rather ragged due to difficulties getting the patron out of the mould.
THe Theophilus one is just a bit complex for me, I'll stick to buckles and pendants and suchlike for now. If there is anything you want cast just carve it in wax and I'll give it a go.


Buy my book about Alchemy in Medieval and Tudor England:
http://www.newcurioshop.com/alchemy-med ... r-england/

User avatar
Fox
Absolute Wizard
Posts: 2652
Joined: Wed Jul 27, 2005 12:27 pm
Location: Cheshire

Re: Medieval bronze casting

Postby Fox » Tue Nov 16, 2010 8:48 am

Bravo, chap.
I was really pleased at Lanark to see all the hard work was paying off.



guthrie
Absolute Wizard
Posts: 2341
Joined: Sun Aug 14, 2005 8:54 pm
Location: Polmont-Edinburgh

Re: Medieval bronze casting

Postby guthrie » Tue Nov 16, 2010 11:44 am

Cool! Thanks, you know I'd almost forgotten you were at LAnark. Too busy working the furnace. I'd like to know more about what the public got out of it though.


Buy my book about Alchemy in Medieval and Tudor England:
http://www.newcurioshop.com/alchemy-med ... r-england/

Tyra
Posts: 1
Joined: Thu Feb 03, 2011 2:13 pm

Re: Medieval bronze casting

Postby Tyra » Thu Feb 03, 2011 2:26 pm

Brilliant!

I have been trying unsuccessfully to melt my bronze. I have tried four times and although my fire is really hot, it won't melt. I bought the ancient bronze from Rio Grande. It has a melting point of c. 1800 C. I am thinking that the mix I have is not what I should be using since the other sites that I have visited mention a melting temp of c. 1200 degrees. Where do you get your bronze? Do you have any suggestions for me? Thank you.



User avatar
mattb
Posts: 84
Joined: Thu Apr 20, 2006 12:27 pm
Location: Worcestershire/Herefordshire
Contact:

Re: Medieval bronze casting

Postby mattb » Sat Apr 16, 2011 4:03 pm

Tyra wrote:Brilliant!

I have been trying unsuccessfully to melt my bronze. I have tried four times and although my fire is really hot, it won't melt. I bought the ancient bronze from Rio Grande. It has a melting point of c. 1800 C. I am thinking that the mix I have is not what I should be using since the other sites that I have visited mention a melting temp of c. 1200 degrees. Where do you get your bronze? Do you have any suggestions for me? Thank you.


I use modern techniques so a little different but my silicone bronze melts at a much lower temp (can't remember the exact temp off hand) but closer to the 1200C the actual crucible temp has to be higher obviously. I'll check my notes on monday.

Matt


Hand crafted reproduction armour and metalwork.
http://mattblackarmour.co.uk back online!

Lost wax cast bronze fittings.
http://bayleyheritagecastings.co.uk/
Follow us on Facebook...
https://www.facebook.com/Bayley.Heritage.Castings

guthrie
Absolute Wizard
Posts: 2341
Joined: Sun Aug 14, 2005 8:54 pm
Location: Polmont-Edinburgh

Re: Medieval bronze casting

Postby guthrie » Fri Jun 17, 2011 12:36 pm

1800C? You mean 1800 Fahrenheit, which is about 982C, which is a low but still reasonable temperature for a bronze alloy. I'd need to check my books for the actual temperatures for alloys, but you can do 1,000C in a charcoal fire with bellows without too much trouble. The problem is getting enough of an overheat to ensure it stays liquid and pours well into the mould, they seem to reccoment around 200C.


Buy my book about Alchemy in Medieval and Tudor England:
http://www.newcurioshop.com/alchemy-med ... r-england/


Return to “Creative Works”

Who is online

Users browsing this forum: No registered users and 1 guest