The Way That I Cast – The Lost Wax Process

I have had several folks ask me questions lately about how I cast my pieces for my shop, so I decided that it was time for a brief explanation and some pictures of my shop.

The process that I use for the majority of my cast pieces is called Lost Wax. It all starts with waxes. The picture below shows a few waxes that have been molded and could be turned into metal pieces. The different color waxes indicate that the wax has different characteristics. The blue wax is more brittle, but it is much better for carving. I often use this wax if I am going to repair a wax that was created from a mold of an original artifact. The details on the original may have been damaged by the ravages of time, and need some fine tuning, or there may be a broken loop or other needed repair.


These waxes were created by injecting wax into an existing mold. They can also be made by carving a piece of wax to create an original master. I rarely use a wax master  when I cast. Instead I make a mold of that wax and use the mold to create copies of the master. This avoids the problem of having a failed casting attempt destroy your wax master, which usually takes quite a while to create. Here is a picture of the wax injector that I use for most of my wax casting.

Wax pot and molds

As you can tell from the drips, this wax injector contains red wax. It requires an air compressor to provide the “push” to inject the wax into the mold. The wire shelves contain an assortment of wax molds. The differences in color indicate that they are made out of different molding compounds. The green molds are made using RTV – Room Temperature Vulcanizing Silicone. That compound will harden to form a mold at most normal room temperatures. The tan molds have to be cooked in a special machine, called a Vulcanizer, in order to harden. The odd looking contraptions on the table to the left of the wax injector (with handles that look like drawer pulls) are special mold clamps that provide a reliable and steady amount of pressure on the outsides of the molds for when you want to inject them with wax. An improperly clamped mold will allow hot wax to squirt out all over. Since the wax is between 150 and 160 degrees Fahrenheit, this is both messy and a bit painful to get on your skin.

This is a picture of a Vulcanizer. The mold material, with the metal model inside, is placed in a frame between two sheets of metal, and clamped between the jaws of the Vulcanizer. The thermometer is used to double check the exact temperature of the jaws before the mold compound is put in place. The mold is allowed to cook for between 20 minutes and several hours, depending on the thickness of the mold and the type of molding compound being used.


Next Time: So now that we have waxes, what next? We turn the waxes into a mold!


What Size Were Brooches in the Middle Ages Part 2 – Bronze Brooches and Other Tiny Things

Last time I mentioned the fact that a lot of pre-1600 items are actually quite a bit smaller than we might modernly assume. In addition I mentioned the easy manufacturing techniques involved in lead and tin items.

Bronze requires dramatically more heat – nearly four times the heat! Temperatures near 2000° F require a furnace, with some sort of blower system, like a bellows. Bronze items would therefore have been a more specialized and expensive production. Not as elite as silver or gold, but not the bottom rung of lead and tin either. And even more important, bronze is much stronger than tin or lead.

Getting back to tiny things, let’s talk a little more about tiny brooches. Tiny brooches can’t be used on thick fabrics. This does NOT mean that they can only be used on linen, cotton, or other plant fiber fabrics. It just means that the fabric needs to be relatively thin.

Brooches like the little one that I bought have a big advantage over penannular brooches. A penannular brooch, if tugged and shaken enough can eventually open. But an annular brooch has to break, bend a lot, or have the fabric that it is attached to tear in order to let go. This gives it a couple of big advantages over the other forms of simple closures that were available pre-1600. It won’t open and it can lay super flat.

ringandbrokenringbroochesThe brooch on the left is an annular brooch and the one on the right is a penannular brooch, with a dime for scale (18mm). I chose a heart shaped annular brooch because I wanted to make a point about annular brooches. They must form a closed ring, but that ring can be just about any shape.

What forms of closures were available pre-1600? Laces or ties, hooks, hooks and eyes, buttons and toggles, penannular brooches, annular brooches, fibulas, dress pins, and other miscellaneous brooches. We already discussed penannular and annular brooches, so let’s look at the other options – remember we are looking at tiny things here, preferably things under half an inch, because that was the size of my little brooch. And there must have been a reason for that size, right?

Laces and ties. Easy to make, inexpensive and widely used. They can be made by the average person with commonly available supplies. They can be made to lie extremely flat, but they can break or untie, and it is very difficult to make them really tiny and still have sufficient structural integrity.

Hooks, and hooks and eyes. Exactly what is the difference? Modernly hooks and eyes are small metal sewing accessories that are available at any sewing supply store. Pre-1600 folks did have small hooks and eyes that were made out of metal wire, and they were definitely used extensively in the 1500’s, but there were also many other types of hooks used, and even some large cast hooks and eyes. Earlier cultures, like the Celts and Anglo Saxons sometimes used what I call “hooks and eyes on steroids” – sets where the individual pieces are each an inch or more long.

hooks and eyesThis picture shows a modern selection of hooks and eyes in various sizes on the right (the numbers are the sizes) and a 1500’s collection of hooks and eyes, from the Netherlands on the left. The size 3 modern hook is about 7/16th inch tall (12 mm).

So, if size is an issue the large hooks are out. The tiny hooks and eyes can lay fairly flat, and they meet the size criteria, but unlike many of their modern versions they did not have a little “bump” on the inside of the hook that make the hook and eye set “lock”. This means that the older hook and eyes would have to rely on tension pulling on them and keeping them in place. Without the tension, they open.

Next time: Hooks – Sharp and Blunt, and Buttons and Toggles