Back to the Articles Page
• The Lost Wax Casting Process
• Wax: An Overview
• Ceramic Slurry Dipping Schedule
• The Sandcasting Process
• The Chasing Process
• Methods for Joining Bronze
• Patinas
• Investment Casting: 1930-1950
• Project #2: Sandcasting a Bas Relief Bronze Plaque
• How to Build a Bronze Casting Furnace
• Foundry Safety
• Furnace Lighting Procedure
• Project #1: Direct Wax Sculpture, Ceramic Shell Casting

The Chasing Process

Well, your sculpture has been cast and it’s cooling on the foundry floor. What now? Once it is cool, you will need to remove all the investment, cut off any sprues, runners and vents, grind the gates smooth, fix any flaws, refine the surface and put on a patina. Here is a chart going over the process step-by-step and showing the more common tools you might use. Each artist has tools that are their favorite; so don’t hesitate to try something different (as long as it is safe!).

Flaws

Fixing flaws are a usual occurrence. At best, you may get a perfect casting, but this is not the norm. Some piece of investment, a bubble, some flash or other unforeseen problems will create a flaw in your sculpture.

In the case of small flaws, you can simply grind off the surface of the material until the flaw disappears. However, if the surface in that area is important you must somehow fill it without ruining too much detail. There are two common ways to do this: 1) you can use a blind rivet, or 2) you can braze some material into the hole. A blind rivet is best for filling pinholes. This method can be used for larger areas by cutting out the flawed area with a chisel and inlaying a small plate of the same material to fill it. It is easier to braze some of the parent metal using a MIG or TIG welder into larger flawed areas. The problems encountered with this are splatter and the lack of control inherent in the welding process. Splatter can be controlled pretty well by covering the surrounding surface with a wet cloth or heat resistant welding tarp. Once the area is welded, the surface must be finished once more and detailed to match the rest of the piece.

Define Detail

Once all flaws are fixed, the surface must be finished. Angle grinders with sanding disks, die grinders using rotary files, hand tools such as small chasing tools are used to refine the surface.

Chasing Tools

Chasing tools are punches with different shaped ends for stamping shapes altering surfaces. They are made from tool steel rods 1/8” to 1/4” or more. Some examples of shapes are shown below.

Chasing tools can cost $7 and up, but small chasing tools can be made from masonry nails that can be purchased at OSH. Masonry nails are made from medium-carbon steel and the tip can be ground to the desired shape. Be careful not to heat up the end so much that it turns color (blue or grey), as this will soften the metal. To avoid this dip the end in water every few seconds when grinding.

Larger chasing tools can be made from 1/4” O1 tool stock that can be purchased at metal suppliers. This metal must be heat treated once the tip has been made to the desired shape. We will cover this in a later class.

Surface Finish

Once the surface of the piece is as desired, it is once more sandblasted to remove any oxides and unify the finish. From this point a patina may be applied or it can be wire brushed, polished, buffed with a scotchbrite pad (by hand or disc), or surfaced in any way you want. Patinas may be applied to the sandblasted surface, or to any other surface desired as long as it is free of oil and oxides.