Where to Get Potassium Nitrate (Saltpeter)

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How to Get Potassium Nitrate

A lot of readers ask where they can find potassium nitrate or saltpeter, which is a common ingredient in many pyrotechnic recipes and other home science projects. Historically, guano from bats was the source of the chemical. Assuming you don’t have a bat cave handy (or want to purify it from your own urine), your two choices are purchasing it or making it from other chemicals.

Get Potassium Nitrate From a Store

Some types of stump remover are nearly pure potassium nitrate.
Some types of stump remover are nearly pure potassium nitrate.

Where do you find potassium nitrate in a store? The answer: stump remover. Spectracide’s Stump Remover is potassium nitrate. In the United States, it is available at Lowe’s or Home Depot, among other places.

The chemical is also readily available online from Amazon, chemical supply houses, or firework/pyrotechnic supply stores. The salt is either a white powder or else a colorless or white crystalline solid.

How to Make Potassium Nitrate

Also, you can make potassium nitrate yourself from salt substitute and a cold pack. Alternatively, use the pure chemicals, which are more readily available than potassium nitrate.

To make potassium nitrate, you need:

  • 40 grams ammonium nitrate
  • 37 grams potassium chloride
  • 100 milliliters water

The ammonium nitrate comes from a cold pack that lists it as an ingredient. It’s the packet of granules or crystals. Potassium chloride is sold as a salt substitute. Make sure it’s listed as the only ingredient.

The chemical reaction for making the potassium nitrate is:

NH4NO3 + KCl → KNO3 + NH4Cl

  1. Dissolve the ammonium nitrate in the water.
  2. Filter the solution through a coffee filter to remove particulates.
  3. Add the potassium chloride and gently heat the solution to get the salt to dissolve. Don’t boil it.
  4. Again, filter through a coffee filter to remove solids.
  5. Place the liquid in a freezer or on ice. The potassium nitrate crystallizes out of the solution.
  6. Pour off the liquid to get the potassium nitrate crystals. They won’t be absolutely pure, but work for most chemistry demonstrations and pyrotechnics projects. If you like, evaporate the water out of the liquid and recover the ammonium chloride, too. Both chemicals are useful for science projects.

Potassium Nitrate Project Ideas

Once you have potassium nitrate, here are some projects to try:

References

  • Joshi, Chirag S.; Shukla, Manish R.; Patel, Krunal; Joshi, Jigar S.; Sahu, Omprakash (2014). “Environmentally and Economically Feasibility Manufacturing Process of Potassium Nitrate for Small Scale Industries: A Review”. International Letters of Chemistry, Physics and Astronomy. 41: 88–99. doi:10.56431/p-je383z
  • Roark, Stan (February 27, 2008). “Stump Removal for Homeowners“. Alabama Cooperative Extension System.