Last year the Bronze Casting Festival was a wonderful experience. People from all over Europe came and exchanged information about bronze casting and metalworking techniques.
Here are a few photos of the First Bronze Casting Festival in 2017.
My talk on air flow and furnace design
Casting with Heide Nodegaard
Casting with Mark Vyvyan-Penny
Pumping Viking bellows. It’s a bit more work than Roman ones, or even bag bellows.
Pouring into stone moulds.
Stirring the bronze to make bronzing powder.
My furnace and bellows
A small Roman furnace designed for jewellery casting.
Bronze Age Bunsen burner
Chris Stein carving stone moulds.
I’ll be returning there again this May and furthering my experiments in metal finishing. In addition to casting, I’m interested in using metal oxides as colorants for enamels and how they are affected by the reduced environment of a charcoal furnace. In the past I did a lot of metal enamelling in an electric furnace. This will be a chance to explore how the process of enamelling could have been developed. I might even have a chance to make some glass while I’m at it!
Bellows are a bit of a mystery. We know they had to have existed in the Bronze Age, but the only physical evidence we have consists of fragments of tuyeres. An Egyptian painting from the Tomb of Rekhmire, from 1450 BC shows a man using pot bellows that are operated by hands and feet. There are also Chinese documents depicting the use of box bellows. But bellows, after blowpipes, are likely to be one of the earliest forms of delivering air to the furnace. Unfortunately they are also constructed of ephemeral materials.
Scene from the Tomb of Rekhmire. The man on the right is operating a set of pot bellows. The valve is opened when he lifts both his foot and pulls on the cord attached to the top of the bellows. The air is pushed out of the bellows when he steps down. These require a lot of coordination.
Until a set of bellows is uncovered preserved in a bog somewhere a lot is left to the imagination. How big or small could they be? How can the valves be altered to be more efficient? How heavy should the leather be? Should sturdiness trump suppleness? How are all the parts held together and made airtight? Bellows are one of the most essential pieces of equipment that we have for casting bronze and yet very little information is available about their origins, and we rely on information for their use and construction from the community of experimental archaeologists and reenactment groups.
Over the years I’ve seen many different shapes and sizes of bellows and always thought that a forum where bellows design and use could be discussed would be invaluable for people to share ideas and experiences.
I would like to invite others to share photos of the bellows they’ve made on this site. This could be a welcome forum for discussing the pros and cons of different designs, what worked, what didn’t. Of course any news of archaeological bellows or tuyeres discovered would add to the fun.
Note the round bottom. a good way to keep the bellows from deflating if they are pulled up too high.
The new bellows, ready to use
Close-up of the new bellows showing how the valve and handles were assembled
An earlier set of bellows by Morgan van Es. These had smaller bags and took more work to deliver enough air to the furnace.
Note the depression along the top of the tuyere. The tuyere is made from wood in which a deep groove was cut. Then the tuyere was covered in leather. Much less labour intensive and it delivers the air very well.
A close-up of the tuyere that Morgan made for the bellows
Pump Bellows
Matthias’ bellows: I saw these at the 2018 Bronze Casting Festival at the Bronzezeitehof in Germany. The handles can be adjusted at an angle, and they have other nice features.
Note that a small nail and a bit of string can give you more control and make it easier to close the bellows when the valve is on top.
These bellows have the leathering on the outside. This decreases the possibility of air leaks, but also limits the height that the bellows can be drawn. That said, they did deliver a lot of air with little effort.
I would welcome others to send in photos of their bellows, and not just bag bellows, any bellows that could be considered to fit in with what we know or can surmise from archaeology would be interesting for this forum.
