• MattBajor

Progress Update: "Petit Grand"

Well, I am very satisfied with what I've gotten done this week; the first full week in my new shop. As you all know, the world has seemingly been turned upside down in the past few months and unsurprisingly has nudged me towards a change in direction. While my passion is for the large and impressive, times dictate a need to (at least for the time being) switch to small and complicated. The project that was originally named "Les Trois Tetons" and stood almost 15' high has been adapted as I still cannot get the design out of my head.


What I have decided to do is scale the sculpture down and instead of welding a stainless steel skeleton and covering it with perforated aluminum, I am going to cast the structure from aluminum and cover the facets with the same dichroic glass as Double Diamond uses. I have created a "proof of concept" that is getting close to my liking:



One of the awesome characteristics of the dichroic material is that the color changes based on the angle. You can see the effect here as I move it around by hand:




The Process

Building this sculpture involves a multi-step process with a fairly high level of complexity, which is what I'm into :) Luckily lost-wax casting has been around for ages and so there is a dearth of information available as to how it's done. One of the videos that inspired me, though he is using a slightly different process, is this gentleman:



He is using a process called "sand casting" in which an imprint of the piece to be duplicated is made in a special sand that is designed to retain features when packed around a three-dimensional object. The process I am using is called "lost-wax casting" and it varies only in the way the final mold is generated. There is an example of this process on display at The National Museum of Wildlife Art where my wife works. Here's a couple of pics:



In sand casting, the mold is made from the imprint of your part in the sand. With lost-wax casting, you create a mold around a temporary substrate (like wax) using investment plaster and then melt out that substrate prior to filling the mold with your casting metal. This leaves a hollow plaster shell that can accept the molten aluminum and allow it to solidify. The process allows you to create more complex structures while still capturing a very high level of detail.


Let's dig in a bit deeper and go through the steps as I understand them.


Equipment

I have to fabricate some equipment to complete this project. The commercially available alternatives are just too expensive for my current situation, and I also enjoy making tools.