Piezoelectric crystals produce electricity when pressure is applied to them. These crystals often are used in electronic devices, especially small ones requiring minuscule electrical connections. Rochelle salt is one kind of piezoelectric crystal. It is less dense than other varieties, and it is the cheapest and easiest to produce at home. You might already have most of the required ingredients in your kitchen.
Preheat your oven to 65.6 degrees Celsius. The oven must be at full temperature before you begin heating your first ingredient.
Pour 1 pound (usually one box) of baking soda into an industrial glass mixing bowl. The bowl must be heat-safe and shatterproof. Glass will not leach chemicals into your baking soda; aluminium or cast iron might.
Warm the baking soda at 65.6 degrees Cor 1 hour. Raise the temperature to 121 degrees C and heat the baking soda for another hour.
Remove the baking soda from the oven, cover it with a towel and let it cool in a dry place while you perform the next steps.
Pour 2 cups of water into a saucepan and warm it over medium heat for about 1 minute. The water should be warm before you perform the next step.
Add 3.5 tablespoons (198gr) of cream of tartar to an industrial glass measuring cup, along with 2 cups of water. Use a measuring cup that can hold 3 cups or more so the mixture does not boil over.
Place the measuring cup in the saucepan of heated water. Bring the water and cream of tartar to a simmer.
Add your heated baking soda to the mixture one-half teaspoon at a time until you have added all of the baking soda or the mixture stops foaming when you add new soda. This means the solution is supersaturated.
Place a coffee filter inside a sieve and place the sieve on top of another measuring cup. Pour the baking soda-tartar mixture into the coffee filter, letting it filter slowly into the second measuring cup.
Heat the mixture in the second measuring cup until it is reduced to about 1 2/3 cup. Place the mixture in a cool place for about a week.
Check the mixture. There should be small crystals in the bottom. Filter the mixture through a sieve to capture the piezoelectric Rochelle salt crystals.