This video documents the process of transforming a 3D-printed PLA skull candle holder into a cast iron decorative object using specialized investment casting techniques. The creator details the preparation of the mold using silica sand and sodium silicate (water glass), followed by a burnout cycle performed within a homemade microwave kiln. After melting approximately 500g of cast iron, the metal is successfully poured into the clamped mold. The video highlights technical experiments, specifically testing the use and tightness of clamps to prevent mold cracking. The final cast iron skull is finished by applying olive oil and heat from a blowtorch to achieve a deep, protective patina.
Creating a Cast Iron Skull via Microwave Kiln Casting
0:17 Project Concept: The goal is to take a store-bought Halloween decoration—a skull candle holder identified as a 3D print (PLA)—and reproduce it in cast iron.
1:09 Pattern Preparation: The skull is 3D printed in translucent PLA. Layer lines on the top of the skull are filled with wax to smooth the surface before molding.
1:18 Mold Creation: The investment mold is prepared using a mixture of fine silica sand and sodium silicate, commonly known as water glass.
2:00 Burnout Process: The mold is initially cured by cycling it in a microwave and is then transferred to a microwave kiln for burnout.
2:15 Burnout Challenge: Due to the mold being wet, the foil stuck during the initial phase, requiring a quick change of the kiln cover before the burnout cycle could be completed (removing the molten plastic).
2:34 Metal Calculation: Approximately 450 to 460 grams of cast iron are required for the statue; 514g of metal were preheated using a blowtorch before placing them in the microwave kiln.
3:01 Clamping Experimentation: The creator experiments with external clamps on the mold to prevent cracking during the high-temperature pour, noting that future attempts may require tighter and more numerous clamps.
4:10 Casting Result: The casting was successful, although the mold cracked after the iron solidified. The final weight was close to the initial estimate.
5:46 Finishing Technique (Patina): After cleaning, the finished cast iron skull is treated with olive oil and heated using a blowtorch to create a dark, protective finish/patina.
6:09 Future Plans: The next video is teased to feature the burnout of a resin 3D print.