Harvesting Salt Yourself
You can try the solar salt harvesting process at home. Instead of an evaporation pond, you'll have a glass jar, and instead of water from the San Francisco Bay, you'll use salted tap water. But the process is a pint-sized version of what we do at our salt works.
Here's what to do:
1. Put two cups of tap water into a glass jar (so you can see your experiment).
2. Add one cup of salt. Stir vigorously. The stirring helps dissolve the salt in the water, so the longer you stir, the better. Not all the salt will dissolve, but with enough stirring, you should be able to bring the water up to 20 percent salinity. (That's about 8 times more saline than the San Francisco Bay water we start with, which has a salinity of 2.5 percent.)
3. Let the jar stand for 10 minutes. The excess salt will settle to the bottom of the jar.
4. Carefully pour the clear - but salty - water into another jar. Leave the excess salt behind in the first jar.
5. Set the jar of salty water in a window or outside. Make sure it's UNCOVERED. That lets the sun's warmth evaporate the water slowly. Of course, don't let rain fall into the jar or you'll delay your experiment. You've created a small crystallizer. The salty water, or pickle, in our crystallizer beds is a bright red color, due to algae and other organisms. Yours will be clear because tap water doesn't contain those organisms. But aside from the color, you're in the salt making business now!
6. Let the jar stand for a couple of days (we give it as much as five years). Do you see a fine film forming on the water surface? That's "drift salt" - very fine crystals. It's called drift salt because the wind can blow these crystals away.
7. Wait a few more days. Let the evaporation continue. The salt crystals will grow bigger until their weight overcomes the surface tension of the water and they sink to the bottom. The crystals will also form on the sides of the jar, just as they collect on the bottom and sides of our crystallizer beds. BE PATIENT! This is a very slow process.
8. Once you have a good crop of salt crusted on the jar, you're ready for harvest. First, drain off the remaining water in the jar, which is now about 3 percent saline.
9. Now scrape the salt crystals from the bottom and sides of the jar. At Cargill, we scrape the salt from the crystallizer beds with a machine-driven plow; you will probably have better luck with a butter knife. BE CAREFUL - your salt crystals are clinging very tightly to each other and the glass, and the jar could break. Be sure to wear a pair of GLOVES to protect your hands in case the jar breaks.
Congratulations - You're a salt farmer!
Kids' Page
Harvest Salt Yourself
Make a Mummy
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