How to measure saturated salinity and mineral levels for flaked sea salt?

Question

I am a sea salt enthusiast looking to make the perfect flakey sea salt. I start with sea water and boil it down to a thick brine. Then with less heat I reduce the brine more slowly and inverted salt flake pyramids are made. I am looking for tools/instruments that will help me measure/understand the content of the brine (mineral content and salinity). Sometimes I get perfect flakey salt pyramids like the photo attached and sometimes I get I get more chunky results. The temperature of the brine is always the same but I get different results at times. This leads me to think that its the content of minerals in the saturated brine solution.

Are there chemistry tools/instruments I can use to understand the actual chemical/mineral makeup of the brine that is turning to salt.

Answer 1

Why not use salt (NaCl) bought from a store, or even better at a defined purity grade from a chemical vendor?

When you use sea salt, you get lots of other ions but more importantly you get colloidal particles, organic substances, and other compounds that will affect the crystallization. Chunky results sounds to me like a colloid particle that started crystallization in all directions at once.

If you want perfect crystals, do it perfectly, i.e. with a pure solution, in a clean and new glassware or polished stainless container. If you want perfect crystals you have to reduce the new-age-ness of it ;)

As for understanding, nobody fully understands crystallization, but a lot of things are known. There are books on this topic, check amazon and search for "crystallization". As for instruments, x-ray fluoroscopy and diffraction wouldn't be amiss but you will get very far with an optical microscope, I know I can watch crystals through a microscope for hours and still find something interesting. Barring XRF, XRD and microscope, and within a household budget there are salinity measurement probes and conductance measurement probes which will be able to tell you something of the brine such as it is.

Answer 2

There's no good way to quantitatively or semi-quantitatively analyze for Na, Ca or Mg at home. You could investigate Ion Selective Electrodes and see if they'll give you the desired accuracy (ThermoFisher has Cl, Na, & Ca I.S.E.s which generally can be simply plugged in to a pH meter and then calibrated). Two other things worth mentioning: you need to filter ocean water - bacteria, algae, and all sorts of other organisms will be present in varying amounts, not to mention silt, and other colloidal inorganics. There also could be differences in dissolved gasses present. So, you need to standardize your handling of the water - from where you get it, to where and how you store it, to how you filter is, and how you process it. Don't assume that mixing it - or shaking it won't affect it. Try to figure out what you're doing to get the crystals you want. It's unlikely, imho, that the Na, Ca, Mg content varies much (although you should treat my opinion as a layman's - I've no direct experience with sea water variability.) I AM assuming you know enough to understand what near-by rivers and recent rains and obviously wind and tidal currents might do to change the composition of the surface water (not to mention air temperature and sunlight). Anyway, one of the cheapest easiest ways to determine dissolved solids is using a specific gravity bulb. (as long as temperature is held constant) You simply float the bulb into the solution and read from the scale what the density is. Finally, what container are you heating this in? Be aware that aluminum should not be used! And I'd prefer glass to stainless steel, but as long as there's no visual signs of corrosion, ss is probably ok. Also, while I'm sure you want a "natural" product, seed crystals of store-bought sodium chloride might make the crystallization more reproducible. Chemists are taught to scratch the glass side of a beaker to start crystallization. Scratches are also a site which may "catalyze" crystal formation, and since any semi-commercial (?) process can't use a new polished pan for each batch, maybe scouring the pan consistently before each batch is the way to go. HTH, these are mostly random thoughts of an industrial chemist kibitzing in an area he has little experience in.