Glass to Cast: Fluid to Rigid STEAM Work

Please always have an adult assist you and supervise with this project.

Karen LaMonte uses a lot of different media to make her amazing pieces. She casts her sculptures in glass, metal, and clay, pouring the molten material into a mold where it will set and become solid (kind of like pouring water into an ice tray to make ice cubes). You can check out this idea of fluidity to rigidity at home by making “hot ice”. The best part is: you probably have all the materials you need already in the cabinet! 

You will need:

  • 4 cups of white vinegar {acetic acid}
  • 4 tablespoons of baking soda {sodium bicarbonate}
  • a cooking pot
  • a glass measuring cup or mason jar {heat safe glass}
  • a glass dish
  • a spoon

Make It: 

  1. Pour the vinegar into the pot.
  2. Add the baking soda (slowly so it doesn’t erupt over the sides of the pot).
  3. Stir until the fizzing stops.
  4. Boil the mixture over med-low heat to reduce it by 75% (about an hour or until you have ¾ to 1 cup remaining). Boiling it slowly helps it to keep its white-colorless aesthetic. But if it turns yellowish, the experiment will still work.
  5. Pour this mixture into the glass measuring cup and place inside the refrigerator to cool.
  6. Scrape some of the dried powder (sodium acetate) from the inside of the pot and place in the center of the glass dish to use later in the experiment. 
  7. Once the liquid mixture has cooled (around 30-40 minutes) remove it from the fridge, careful not to jar, stir, or disrupt the mixture.
  8. Begin slowly pouring the liquid onto the sodium acetate powder and watch as it crystallizes into a solid substance!

Why It Works: 

This is nucleation, or the beginning of crystallization. The baking soda and vinegar combine to form a sodium acetate, but it is still very dilute (watery). Boiling it causes some of the liquid to evaporate making it more concentrated.  The sodium acetate on the glass dish becomes a nucleation site (seed for rapid crystal growth) for the solution you are pouring onto it. The thermodynamic changes that are taking place due to crystal formation are the reason the liquid is still warm/hot when you take it out of the refrigerator. Don’t worry, though, it shouldn’t present a burning hazard.