Firing glass with bronze might sound impossible, but it is actually very easy to do. You still need to use carbon to assist the bronze with sintering. So, how do you protect the glass from getting carbon in it?
In this tutorial, I will explain how to build a steel mesh box to place over your glass during firing. This technique allows for limitless design options. And, white bronze is the perfect non-precious metal to use with your glass. It fires in exactly the correct range for adhering the glass to the surface of it.
We will be using Five Star Metal Clay and a two-phase firing schedule.
Project Materials and Supplies
-50g Five Star White Bronze
-Non-stick rolling pin
-Textures and molds
-Playing cards or depth measuring slats
-Fine steel mesh
-Olive oil or Liberation Spray
-Nail files, metal files or baby wipes
-Tissue blade or craft knife
-Small coffee straw
-Polishing bristle disks
-Steel firing box
-Activated coconut carbon
Set up your workspace. Anything that comes in contact with the clay should be covered with a light coating of olive oil or other resist agent. This includes your hands and non-stick surface.
During firing, glass will fuse to the metal clay. This fusion allows the design more flexibility in creating a setting for the cabochon. Your design will need to have a surface of metal behind the cabochon, and an element of depth around the cabochon. The element of depth will protect the cabochon from damage during wear.
Working quickly, roll out the clay using playing cards or measuring slats to regulate thickness. The finished thickness should be 6 cards thick. Cut the shape of your desired piece.
Set the wet piece aside to dry. Create elements to attach to the surface of your piece. You will be alternating working in wet and dry clay. The clay will need to have some strength to hold your elements, however it does not need to be completely dry.
Place a large drop of paste on your piece where the glass is going to sit. Firmly place the glass making sure to push all air bubbles out of the paste.
If you have any cracks, this is the time to fill them with a bit of paste on a paint brush. Dry again. Repeat until the crack is fixed. Support piece on a rubber block as you work. Use sandpaper, nail file or baby wipes to refine edges. If baby wipes are used, let piece dry again. When your piece is refined to your desire, drill two holes in the top for jump rings.
Using a two phase firing, burn off the binder on a steel mesh in the kiln. For this clay I fired at 1000ᵒF for 10 minutes.
Create your fine mesh screen to cover the glass but as little clay as possible. Cut a piece of fiber paper to match the size of the mesh box.
Place carbon in the bottom of you steel container. Place the piece on top of the carbon. Place the mesh box over the glass and lay the fiber paper over it. Then gently pour carbon on top to fill the container being careful not to get it under the mesh box. Fire at the recommended sintering schedule. For this clay I fired at 1300ᵒF for 1 hour. Remove from carbon when cool.
Handle the fired piece with care. White bronze can be delicate after firing and needs to be work hardened. Gently brush with a stainless steel brush (do not use brass on white bronze). Using bristle disks, start with the heaviest grit and work your way down to a fine grit. This helps strengthen the piece and is the best way to create a beautiful silver color shine on your white bronze. This piece has deep detail, so I started with large disks then moved down to the small ones to get into the recesses.