Category Archives: Metal Working

The Way That I Cast: Lost Wax Process Part 3

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Last time we created a mold by using a wax model and investment. But is it really a mold that we can pour molten metal into yet? Nope! We now need – Heat, Heat, and More Heat!

Right now the investment is still soft and it still contains waaay too much water to be anywhere near molten metal. Most of the wax has been melted out by the dewaxer, but the investment now needs to be hardened, the remaining wax needs to be burned away, and any remaining moisture in the investment needs to be driven off. The way this is accomplished is by placing the flasks into a burnout oven and cooking them for hours. Here is a picture of my burnout oven.

burnout oven

And yes, 947 is the temperature in the oven. This is actually the low end of the temperature cycle, the temperature at which the flasks are held, at the end of the burn-out cycle while they are waiting to be cast. The high temperature portion of the cycle varies, depending on exactly the type of investment that is used, but it is often around 1300 degrees Fahrenheit. The burnout cycle starts slowly, at about 200 degrees and gradually increases. By the time it is at 700 degrees we open all of the windows and doors in the Studio to let the fumes out. Burning casting wax is a truly nasty smell, and not good for you. By the time the cycle is finished and we are at the holding temperature, about eight hours later, the smell is gone and there is no more wax residue left in the flasks. They are now officially molds!

Once the end of the casting cycle is coming to an end it is time to start melting the metal. I have two electric melting furnaces, a small one that uses a removal crucible, and a bigger one, which is called a “tilt and pour” This just means that you pick up the entire furnace and pour the molten metal directly from the furnace into the flasks.  In either case I have to preheat the graphite crucibles in the furnaces, add the new casting grain and the old metal that I am re-melting, and wait. If you peek into the furnace while it is heating, this is what 1980 degrees Fahrenheit looks like.

recently recharged furnace

Once the metal has melted completely, I start bringing the flasks out of the burn-out oven one at a time. The flask is placed on the silicone pad on the vacuum machine, the vacuum is turned on, and the molten metal is poured into the flask. And this is what it looks like.

big furnace pour

The vacuum machine is actually pulling air out of the bottom of the flask, which helps produce better castings. The flasks are removed from the vacuum machine and set aside to cool. Here is a picture of three flasks cooling on a metal cart. They are sitting next to my small furnace.

small Furnace with flasks

This is a great picture because it really shows how you can see what temperature the metal is by its color. The right hand flask is yellow because it is the hottest. The almost black metal on the left is ready for the next step in the process.

Next Time – What Happens Now That We Have Poured the Metal?

Purses Part 12: How Were Purses Used Historically?

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Now that we have the concept of how a Medieval metal frame purse is made, we should probably look at how they were used. I am not talking about what people put into their purses.  We can safely assume, since there are paintings of people taking coins from their purses, that they were sometimes used to hold money. I mean that we should try to understand how they wore their purses. What sort of options did they have?

Modernly, in most of the reenactment groups that I have seen, a purse is often hung directly from a belt. I have done this many times myself, and one of the problems is that if the purse is heavy it will tend to crease, roll, or fold the belt in an uncomfortable fashion. The physical abrasion of the purse cord can also damage the belt. We see lots of people in illuminations with all sorts of purses just hanging on strings or straps from their belts. But there is another solution, which also prevents the damage to your belt, and gives you yet another opportunity for bling. I am talking about purse hangers.

It is difficult to know how common purse hangers were in period, but a quick search in the Portable Antiquities Scheme Database reveals quite a few. I cast a couple of the most common forms of these hangers a couple of years ago. The first one that I cast was this one.

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We see several versions of this form of purse hanger, some with, and some without the bar. These purse hangers were usually permanently attached to the belt with rivets. This graphic shows how this cast piece is used. The string of the pouch can simply be looped over the suspended metal frame.

purse hanger

Here is a link to an actual example of this type of purse hanger in the Portable Antiquities Scheme.

Another common form of this hanger does not have the bar and uses two separate supports that are riveted to the belt, like this.

purse hanger two supports

The other form of purse hanger that I cast was this one.

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Here is an example of a similar purse hanger from the Portable Antiquities Scheme,

This type of hanger was attached to the belt with a piece of the metal and rivets just as in the previous examples.

There are many other forms of purse hangers, from simple hooks like this one to hangers with much more complex shapes than the ones that I cast.

I think that purse hangers could be a fun addition to a fancy outfit, and casting a couple of other shaped purse hangers is definitely on my “to-do” list. I hope that this sampling of purse hangers inspires you to try adding one, or more, to your collection of accessories.

Purses Part 11: Finishing Up the Frame

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Last time I created eight gauge bronze wire wire purse frame rings and fitted them to the purse frame, but now we have to hold it all together.

When I was doing my original research I noticed a number of purse frames that appeared to have some sort of washer on the end of the purse frame bars. I decided that I liked the look of the washer and that the washer would also make for a more secure anchor for the rings on the purse bar. So when I was creating the original waxes from the replica, I also created some round washers that I thought would look good on the purse bar. I admit I guessed at the size, based on the size of the purse, but when the time came to actually use them, they were the right size. Here is a quick picture of some of my original cast pieces, including the washers.

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So I fitted the washers on to the purse bar, trimming the length of the purse bar end and smoothing it, and then riveted it together. And here is the result.

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The look of the washer was the perfect finishing touch for the frame.

What I learned from the Riveting process. No matter how careful you are measuring and hammering, it doesn’t always work the way you want it to. I broke one pivot trying to rivet it, and I also broke a hexagonal washer by accidentally cracking it – the casting actually had a tiny crack in it that I did not notice. Having a hole in the washer that is too tight can also cause the washer to crack when it is riveted. The pivot will expand a little bit, and too much expansion can crack the washer. And then there is the purse bar itself. Yes, I broke one of those, too.

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So where do I go from here? I will be working to fine tune the purse bar pieces. For a first try they are fairly close, but I will be modifying the pieces to make them a tiny bit sturdier, and I also want to improve the fit a little. Once I am pleased with the final look of the purse frame, I will be recasting it, and then I will be experimenting with casting purse frame rings. I really want to have the strength and stability of the “L” shaped purse ring and the ability to easily sew the purse bag onto the frame. And then what? I have a much larger broken purse frame bar that I think would make a really awesome larger purse…

Next time: How were purses used in period?