So we started our apprenticeship with Doug Swenson as part of the Folk and Traditional Arts Apprenticeship grant that we received. The work plan was originally developed about six months ago and we’ve learned a lot since then. And we are about to leave on a trip and be away from the forge for several weeks so we kind of are starting out of order with the Viking-age bellows.
We’ve used Viking-age bellows once or twice and they are surprisingly easy and fun to use. There’s actually not a lot of information about them because they haven’t survived through time very well and they aren’t mentioned to often in literature or historical accounts. There is a cool depiction of one on a runestone from Sweden.
We spent a bit of time going over how bellows evolved and how they work. Some have a single chamber and others have a double chamber. Later ones got rather large and hung overhead, operated by a lever or a foot pedal. But they all essentially work the same way: air goes in one end and is directed out as smoothly and steadily as possible out the other end. And valves in the middle keep the air moving in one direction.
So we started talking about the valves for the bellows we are about to build. In this case we are going to use leather for our valves. It’s a traditional material and actually quite suited to this purpose. The air intake is actually just a round hole cut into one side of the bellows and the valve consists of a couple of pieces of leather that cover that hole. However, there’s a bit of elegant math to the size and placement of the leather pieces. There’s two pieces that are involved. The first is a square large enough to cover the hole plus a bit more. That piece is placed with corners to the front and back of the bellows and tacked down at the sides. The second piece of leather is twice the length of the first piece and covers it and is tacked down at the corners. It should be extremely taut as it will need to allow air to pass through it freely.
After that we looked at the construction of the bellows that our master blacksmith instructor uses in his Viking-age demonstrations. Most of it is very suited to purpose and have stood up to use and time, but we might make a few minor adjustments when we build ours.