DIY Cast Metal Stamp

Carve a metal stamp of any design in wax, then cast it any metal desired.

Metal stamps are useful for marking handmade metal pieces with a signature, date or brand that is difficult to remove and proves the authenticity of the jewelry, sculpture or functional item. A metal stamp is cylindrical and looks like a large, thick nail with one flat end for hammering and the other end a relief stamp. Die-casting is the method most commonly used to manufacture metal stamps, but DIY enthusiasts can make their own custom stamps using investment plaster and the ancient process of lost wax casting.

Things You'll Need

• Metal pot
• Jeweler's wax
• Wax carving tools
• Wax rod
• Ruler
• X-Acto knife
• Wax pen
• Casting flask
• 3 cups investment plaster
• 3 cups room-temperature water
• Electric kiln
• Metal tongs
• Centrifugal casting machine
• Safety goggles
• Leather safety gloves
• Metal for casting
• Crucible
• Bucket
• Ring vise
• Jewelry saw
• Metal file
• Hard-bristled toothbrush

Instructions

1. Boil a pot of water then remove it from the heat source. Submerge the jeweler's wax briefly in the hot water, then remove it. Sculpt the softened wax into the shape of a metal stamp. Carve one end into a relief of the desired stamp using the metallic carving tools.

2. Cut a 2-inch length of wax rod using the X-Acto knife. This attaches to the stamp and functions as a sprue, which creates the passage in the mold through which to pour the molten metal. Plug in the wax pen and turn it on. A wax pen is an electric tool similar to a soldering iron, with a heated point used to melt and join wax. Touch the hot end of the pen to one end of the cut wax rod to melt it slightly, then touch the melted end of the wax rod to the flat end of the carved wax stamp. Hold the two together until joined, for about 30 seconds.

3. Unscrew the cylindrical walls of the casting flask. Insert the free ends of the wax rod attached to the stamp into the hole at the center of the rubber base. Attach the flask walls back onto the base without jarring the wax at the center.

4. Mix the fine investment plaster with the room-temperature water until creamy. Stir with a spoon to eliminate air bubbles, then pour the mixed plaster slowly into the flask until it is full. Tap the sides of the flask for five minutes to release air bubbles. Let the plaster dry for 24 hours.

5. Turn the flask over and remove the rubber base. Place it inside the kiln, then slowly heat it to 1,200 degrees Fahrenheit. Bake it for one hour to dry the plaster further and burn out the wax inside the mold. Decrease the heat to 400 degrees. Remove the flask with metal tongs.

6. Secure the flask in the centrifugal casting machine. Put on the safety goggles and leather safety gloves. Heat the casting metal to molten liquid in the crucible. Turn on the casting machine and carefully pour the metal into the sprue hole. Turn off the casting machine when all the metal disappears into the cast and allow it to cool for 15 minutes.

7. Remove the flask from the casting machine with the metal tongs and submerge it immediately into a bucket of cold water. Agitate the water to dissolve the plaster, then remove the metal stamp and sprue with the tongs.

8. Clamp the metal stamp in a ring vise. Saw off the sprue using the jewelry saw. File down the small bump remaining by using the metal file. Clean the stamp free of investment plaster by using a hard-bristled toothbrush.

Tips & Warnings

• Molten metal can cause injury and even death. Use extreme caution when pouring metal stamps.

References

• "The Complete Metalsmith"; Tim McCreight; 1991
• "Professional Jeweler Magazine"; Article Archives; Cast jewelry: A Primer; Mark B. Mann, May 1999