Using Urine to make Potassium Nitrate

Urine is great stuff; it’s a waste product that shouldn’t be wasted. Although urine is mainly water (95%) it also contains important chemicals that can be used to make gunpowder and fertilizer. The rest of the chemicals in urine are:

  • Urea (which is a nitrogen based organic compound)
  • Chloride
  • Sodium
  • Potassium
  • Creatinine
  • Various small amounts of ions and trace elements

    In this experiment, it is potassium we’re focusing on, but many of the other constituents, even the water, can be made use of.  This experiment shows you how to make potassium nitrate or KNO3 The K is the chemical symbol for potassium, N for nitrogen and O for oxygen. So you can see potassium nitrate s a mix of these three elements.

    Making the Potassium Nitrate

    Potassium nitrate is one of the main ingredients in gunpowder, so when the SHTF knowing how to make this, may well come in useful. The other ingredients in gunpowder are sulfur and charcoal.  Making potassium nitrate the tradition way involves a lot of manure (to supply bacteria), lots of urine (to supply the potassium) and about 10 months for it to percolate.

    How to make your potassium nitrate:

  1. Collect some manure in large container (needs some way of drawing off liquid like a tap or blocked hole)
  2. Add wood ash to the manure
  3. Mix in some straw (this helps to aerate it)
  4. Add urine, lots of it, over time to the wood ash mix
  5. .Stir every so often

ear the end of the process (about 10 months) add a good amount of water and drain off, collecting the liquor

What happens?

Step 1: Solution of potassium nitrate

Urea and any metabolized ammonia are oxidized by the bacteria in the manure to nitrate which react with potassium carbonate (in the wood ash). This forms a mix of soluble potassium nitrate and insoluble calcium and magnesium carbonates. The soluble potassium nitrate can then be drawn off from the mix in the liquid.

Step 2: Crystallizing potassium nitrate

To make the solid form of potassium nitrate used in gunpowder you need to crystallize the potassium nitrate out of the solution.

To do this:

  1. Boil up the liquor you’ve drawn off from the mix with charcoal. This removes the color
  2. .Filter off the charcoal through a cloth
  3. Now reduce down the liquid by gently boiling. You’ll see the liquid reduce in volume.
  4. Start to cool it when you have reduced the volume by about ¾.
  5. Using (ideally) a glass rod or long piece of glass, dip it into the solution, pull out and as it cools if you see white crystals forming you know it’s now a saturated solution
  6. .Cool this down as much as possible (surround the container with ice if you have it)
  7. Filter your saturated solution through a fine cloth, like gauze (or filter paper if you can get some).
  8. The crystals then need to dry out on the cloth or paper

    TIP: When you are forming crystals you can ‘start them off’ by seeding the solution with the crystals on your rod (step 5) and / or scratching the sides of the container with a glass rod. This creates a surface for the crystals to stick to. Once one crystal forms, the rest quickly form around it. One of the most amazing things I’ve ever seen, is the sudden formation of masses of crystals in a saturated solution after scratching the sides of the container, it’s like magic.