We live on an island and often benefit from our proximity to the ocean by harvesting seaweed and compost for the garden, digging clams, and gathering rose hips and wild asparagus that grow untended on the beach. A few weeks ago I found myself buying 8 oz of sea salt for $3.00 at the grocery store and thought hey, ocean! And then I went down to Beach Road Beach for 6 gallons of really clean seawater. I also did some research online. According to various blogs and agriculture sites (and for once, Wikipedia wasn’t all that helpful) six gallons of seawater should produce six cups of salt via evaporation. That seemed like a very high concentration to me, but turned out to be quite accurate.
I chose shorefront with no sewage outflow or houses nearby and a fast-running current. Water from a shallow bay might contain more salt, but is more prone to contamination. I initially forgot that water weighs 8.3 lbs per gallon but remembered pretty quickly when I realized I was downhill from the car with a container that would weigh >50 lbs when full. I finally put the large container up by the car and schlepped buckets up the ridge to fill it. You’ll want your water source to be convenient to your transportation.
Strain the water through a sieve to remove bits of debris and sealife. Don’t empty the container all the way when you pour it into your cooking pot to avoid any sand that has settled to the bottom. It helps to rest the water container on something sturdy above the level of your cooking pot to pour it off. I used a honey sieve to strain the water into a 5 gallon restaurant pail.
If you can possibly avoid it, don’t do this inside! Boiling off six gallons of water took a full day – actually two half days of diminishing sunlight – over a wood fire, and that’s a lot of water vapor to add to the interior of your house. I used a 5 gallon lobster pot a refilled it when necessary but I imagine any non-reactive pot or bucket would do. If you have to use a smaller size, try for as much surface area as possible to encourage evaporation.
I lit a wood fire in my cinderblock grill using slightly punky firewood that the mice have been living in that I don’t want to burn in our woodstove. I only kept the fire going during daylight hours, currently 9 a.m. to 3 p.m. here in Downeast Maine, and it took two days to reduce 6 gallons of seawater down to about 4″ of what looked like clear water and a cup of chunky tan sediment swirling on the bottom of the kettle. At that point I took it off the fire because I was afraid I’d scorch the pot. Boy, was I disappointed!
The remaining water was very salty to the taste, but even the steam coming off the kettle was salty – I didn’t see how it was going to produce 6 cups of salt. I dumped what was left into a large glass baking pan, per directions on the web, and figured I had nothing to lose by letting it evaporate the rest of the way in the house. The next day it had dried enough to appear opaque and slushy, and then crystals started to form. I broke up the slab with a potato masher periodically because the top dried out first.
Now, a week later, I have 5 1/2 cups of large crystal sea salt that has dried quite white like the dish I pulled out first so that we could sample it. It tastes like salt, of course, but there’s also a little extra “ocean” flavor somehow, probably due to the lack of processing. My neighbor describes it as “smoky”. All in all, a good experiment – would try again!