How to Grow Baking Soda Crystals.

These are crystals of baking soda or sodium bicarbonate that have grown overnight on a pipecleaner.
These are crystals of baking soda or sodium bicarbonate that have grown overnight on a pipecleaner. Anne Helmenstine

Baking soda or sodium bicarbonate crystals tend to be small and white. Sometimes they can look a little like frost or icing when grown on a string. Here's how you grow baking soda crystals yourself:

Materials for Baking Soda Crystals

  • Baking soda
  • Water
  • Clean jar or glass
  • String
  • Weight (e.g., paperclip)
  • Pencil or butter knife (to hold the string over the glass)

Prepare the Crystal Container

You want to hang the string in the glass or jar so that it doesn't touch the sides or bottom of the container.

Tie the string to the pencil or knife, weight it so it will hang straight, and adjust the length of the string so that it doesn't touch the bottom of the container.

Prepare the Crystal Solution

Mix as much baking soda as you can into just-boiled water. For 1 cup of water, this is approximately 7 teaspoons of baking soda. Add the baking soda a little at a time, stirring between additions, because carbon dioxide gas will be evolved, causing the solution to bubble initially. Alternatively, heat baking soda and cool water until it is near-boiling. Allow the solution to sit undisturbed for a few moments to allow any undissolved baking soda to sink to the bottom of the cup.

Grow Baking Soda Crystals

  1. Pour the baking soda solution into the container. Avoid getting undissolved baking soda in the glass.
  2. You may wish to cover the container with a coffee filter or paper towel to keep the solution clean while permitting evaporation.
  1. Allow the crystals to grow as long as you like. If you start to see a lot of crystal growth on the sides of the container rather than on your string, pour the remaining solution into a new container. Transfer your string to the new container to get better growth.
  2. When you are satisfied with your crystals you can remove them from the solution and allow them to dry.