The Joy of Discovery

historic trades

Recreating 18th-century technology takes perseverance and luck, says Jay Gaynor, Director of Historic Trades.

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Transcript

Harmony Hunter: Hi, welcome to the podcast. I’m Harmony Hunter. With me today is Jay Gaynor, Director of Historic Trades at Colonial Williamsburg. Jay is back on the program today to update us on the progress of a project that is, I’m sure, consuming all of your time. Jay, thanks for being with us today.

Jay Gaynor: Pleasure to be here.

Harmony: For folks who might not be familiar with this cannon project, can you review what the process is you’re going through and what you’re trying to achieve?

Jay: We’re doing it just to see if it can be done, to be totally honest. We’re reconstructing an 18th-century cannon. It is a reproduction of a British light three-pounder, which was a gun that was developed about the time of the American Revolution and saw deployment over here during the Revolution.

So, there are several challenges. One is getting all the information that we need to build this thing accurately. We want to make it as accurate as possible. The other is attempting this cannon-casting technique, this bronze casting technique, which is new for us.

We have a lot of documentation from the 18th century that explains how they did it then. Of course, like most documentation of that type, there are a lot of details that aren’t filled in. That’s what we’re doing right now. We’re trying to figure out – and we’re finding out – what can go wrong. We’re in the process of trying to think through that and make it work.

Harmony: So last time we talked, you were preparing to pour this first cannon, to pour the metal into the form. What’s happened since then?

Jay: To go back a little bit, the reverberatory furnace that we built worked. We experimented off-site with some folks that were helping us with it, and we weren’t sure, we thought that may be one of the major problems we’d run into, but it worked well, and it worked the first time. So we were absolutely thrilled about that.

The casting that came out, when it came out of the ground, and we broke the mold away from it, looked pretty good. We thought that maybe we’d been lucky all around. Once we started to clean it up, put it on the lathe, started to skim the surface, we realized that we had some major problems with porosity – with little honeycombing on the brass casting itself.

What we’ve been doing over the last couple of months is trying to figure out why that happened, and what we can do to eliminate as many of the variables as possible so we can control the process and narrow down where the problem might be coming from.

Harmony: So you’re getting ready, coming up August 20th.

Jay: August 20th is what we’re shooting for right now to do another test pour. We’re going to cast another coehorn, relatively small. We want to get that right, get our casting procedures down so that they work before we go for the bigger barrel.

Harmony: What are you going to do differently this time?

Jay: Several things. I think just the experience of running the furnace that first time taught us some things. We’re aware of three or four factors that may have been major in what went wrong.

One, we don’t think that we baked the clay mold to a high enough temperature. It probably still had too much moisture in it. So we’re going to literally fire this next mold, and we may even use a modern pottery kiln just so we can control that and make sure that it’s baked to a high enough temperature to provide the porosity and the nature of the material that we need for the mold. So that’s one.

Two, and this was suggested by one of the folks who got in touch with us through the blog, was that we didn’t divert an initial part of the pour at all. So we may have washed some things into the mold that we could avoid by running a little bit of it off somewhere else first and then going into the mold.

Harmony: So you’re saying you have this hot, liquid metal coming down a chute into the mold, and what might have happened is that this liquid metal just from the chute that it was flowing through, might have picked up some debris.

Jay: Or in the furnace itself. We wanted to see if we could get rid of some of that. We don’t think we degassed it properly. When bronze is molten, it tends to absorb hydrogen, and that gives some gas in the bronze itself, which can form bubbles when you pour it. So we’re looking at ways we can do that better.

The other thing that may have happened, we don’t know for sure, is that the bronze may have been too hot. We’ve only got a little door about a foot square, that we can access the bronze when it’s melting. As soon as you put a piece of wood in there to stir it or poke it or whatever, it immediately turns into charcoal. We’re thinking that maybe – we thought that the bronze was still gooey or solid, when in reality, we were dealing with the scum that had sort of formed on the top of it.

So we’re going to try to monitor that better, and probably do something really simple like wearing welder’s goggles so that we can see better what’s going on inside the furnace when we’re getting ready to do the pour.

Harmony: Does this give you a new respect for the way that the craftsmen who were trying to figure this out in the 18th century?

Jay: I think that respect has always been there. It’s interesting, because some of the problems that we’re having are the same kind of problems they were dealing with, which is kind of reassuring.

But there’s no doubt – and again, some of the people we’ve talked to on the blog have brought this out – the folks doing it then started doing this stuff when they were kids, they were working under folks that had been doing it for 25 and 30 years, and there was a huge amount of empirical knowledge about what they were doing.

Trying to start out from scratch like we’re doing is going to entail some, hopefully some good reasoning and research and application. But there’s going to be a good dose of good luck there, too. Because we’re really trying to do something that has been lost for a long time. We don’t have that continuity, there’s no way we can go back to it.

Harmony: So nobody else is making cannons this way anymore. You’re attempting it for the first time in 200 years?

Jay: I don’t know if it’s 200 years or not, because I’m not sure when the technology really changed from the late 18th century on, but certainly nobody has tried to do it like this in the 20th century as far as I know. People are certainly casting cannon barrels, but they’re basically using modern foundry techniques.

Harmony: How will you know you’ve been successful?

Jay: When we get a piece of bronze out of there that doesn’t have holes in it. It’s pretty much that simple. The only way we can really tell that is, once it’s out of the ground, we put it on the lathe, we skim the surface, we see what it looks like.

We expect some surface roughness, that’s just part of the process. If we get what appears to be a good clean surface, then we’ll bore it and see what it looks like internally. If it appears to be solid, some folks have suggested it might not be a bad idea to x-ray it, something we would think about.

Once we think we’ve got something that’s right, we’ll proof it and see what it does. We’ll pull out the casting, we’ll clean it up, we’ll see what it looks like. If it looks good, we’ll see what was a variable and what we had control over, and probably in the cases where we’re using modern technology like firing that mold in a pottery kiln rather than doing it as they would have done in the 18th century, we’ll try to do some reverse engineering and see if we can find out how to do that using the correct period technology.

Once we feel like we’ve got a lock on those things, we’ll go for the bigger pour, we’ll go for the light three.

Harmony: Tell me about the blog.

Jay: The blog is up on the Colonial Williamsburg internet site, it’s called “The Cannon Blog.” We’ve been able to post a lot of photographs there of the cannon up to this point. We’ve been able to post quite a bit of dialogue about what’s happening, including feelings of success that were almost immediately smashed by knowledge of failure.

But what’s been neat about it is that we’ve attracted a huge amount of input from folks that have been interested in this topic for a long time, that have written about it, that have done their own castings. We’re getting some really wonderful input from folks that is helping us a lot to think about what we’re doing and refine the whole process.

Harmony: That’s great. What else are you learning as you move through this process of trying to recreate an 18th-century cannon?

Jay: Well I think as you pointed out, we’re certainly sustaining our respect for the folks that did this during the 18th century sort of as a matter of course. But I think it’s just exciting to do this stuff. It’s detective work, it’s hands-on, and it’s something that Historic Trades is really all about, is taking something that … You know, why do this? We know how to cast cannon barrels using 21st century technology. Why go back 200 years and try to re-figure out how to do it? It’s simply the joy of discovery in many cases. It’s pretty exciting to realize that you’re going through the same processes and trying to replicate something that was a part of everyday life a couple centuries ago that we’ve kind of lost along the way.

Harmony: Great, thanks for being with us, and good luck in August.

Jay: My pleasure, thanks.

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