> Indeed, table salt is often used in kids’ experiments to demonstrate crystallization. It’s a simple activity, but the results are disappointing.
I remember this was one of the things I tried countless times as a kid. It never worked - the books showed these nice, clear crystals but all I ever got was a crust of dried salt and maybe one tiny crystal a few mm across.
I'm sure most of those "science for kids" book authors never tried a single one of their experiments.
i tried a similar 'experiment' once with sugar to make rock candy, failed the first attempt
my grandma saw and told me to use the rest of the string and sugar I had, enough for 12 more tries, and do them at once but in different areas of the house
only two actually grew but i learned the value of spreading risk and unknown unknowns ( much later, on reflection :) )
We did a rock candy experiment in 6th grade and probably attempted it a few separate times, specifically because we kept having issues. I think at least one batch got moldy. But, if I'm remembering correctly (this is over a decade ago), we may have been placing the dishes near where sunlight hit, so that could've been part of it.
Did this as a kid as well. When I got to high school chemistry, we did an experiment on super saturation of the sugar. Much better results, much faster!
hehe I did that super saturation thing as a kid. one of the instructions was pour until saturation happens. It didnt. I ended up with 5 pounds of rock candy.
That was the plan. But never got to the 'super saturation' point where it would no longer melt in. Knowing what I know now I figure the temp was too high. Least I got an A as I had pounds of crystals. We added flavoring and coloring to some of it and gave most of it away.
When I wanted crystals for microscopy, I made a mother liquor by pouring an enormous amount of sugar in a tiny amount of water (beyond saturation) and then just let the solvent evaporate in a heated chamber.
Never heard that term before. Not sure I understand the point though. After you supersaturate and then form crystals, the mother liquor is just the left over content that didn't make it into the crystals. What is the purpose of using those remnants?
Could it be the requirement for "Uniodized table salt"?
I don't think I'd be able to find it around here, and I can't think of any good reason someone would have it on hand either.
Have you actually checked your grocery store? Mine sells both iodized and uniodized table salt, in addition to the kosher salt idea that folks have mentioned. I know the OP said that they worried about anti-caking agents in kosher salt and I'm no expert, but I thought they didn't usually have them.
Doesn't iodized salt have a weird taste? I'm pretty sure I don't have any in my house. I don't think reasonably well-off people in developed countries need iodized salt, because we get enough iodine from our diets.
It wasn't long ago when most of Europe was iodine deficient. It got better recently because of a concerted push towards universal salt iodization but there are still some places that remain iodine deficient, including Germany.
Being from Brazil, where table salt is universally iodized, I have a hard time understanding how in 2021 there are still rich countries out there that haven't figured out a proper iodine fortification program. And we even have some people saying they intentionally prefer non-iodized salt!
On the other hand, there was one time I had to do a short no-iodine diet and it was pain in the ass. I had had to go out of the way to find non-iodized salt and good luck finding any pre-packaged food without iodized salt...
In Poland we have normal iodized salt, but we have uniodized salt just for one purpose - making pickled cucumbers. But our "kiszone ogórki" is not the same as typical pickled cucumbers ("ogórki konserwowe", we have those too). It's more like sauerkraut but with cucumbers. With iodized salt they just spoil.
Dishwasher salt is not actually widely available in the US, since we we generally don't have dishwashers with built in water softeners that need the salt.
Most places either have soft water from their water supply, or people install a whole house water softener, if their water is hard enough to cause problems with mineralizing on dishes.
The salt for the whole house water softener would probably work, but the bags are pretty huge.
> Dishwasher salt is not actually widely available in the US
I am in the Bay Area. I bought some off Amazon no problem. It came from the US too.
> since we we generally don't have dishwashers with built in water softeners that need the salt.
Landlord installed a Bosch dishwasher, which has a water softener. The water is pretty hard (I can see by the shower faucet, and confirmed on the utility website). I'm assuming he didn't bother to import the dishwasher from Europe so it must be available in the US.
Yes, Miele too. All the German brands available in the USA are like that. Salt for them is readily available online and at higher-end appliance stores.
The only brand I even recognize is Finish, and they're a UK firm, not American. Technology Connections mentions[1] it's a European thing: "I have never ever encountered one, and I don't think I've ever seen dishwasher salt sold in a store."
> The only brand I even recognize is Finish, and they're a UK firm, not American
Plenty of non-american firms sell products in the US. Like... I don't know, Nestlé?
I watched the same Technology Connections video. He does mention Bosch dishwashers by name. Those are available in the US. It's just that people barely bother understanding how dishwashers work, let alone _very infrequently_ refilling the salt. Heck, people drive without checking tire pressures, dishwasher salt has no hope.
Not surprising that most stores don't bother. It lasts forever too.
They're pretty rare. I stand by the claim that I've never seen a physical store selling diswasher salt. Before I saw that video, if you told me to get some dishwasher salt at the store, I'd have asked if we also needed any headlight fluid or elbow grease.
Perhaps get a 20kg / 40lb bag of pool salt for $20.
I’m not sure about purity or anti-caking, although some brands are advertised as high purity. You can even get it delivered in the US: https://www.amazon.com/s?k=pool+salt
Perhaps look at the 20kg bags of food salt sold at wholesalers, which might not be iodised. I recall seeing one at a Chinese store, but I’m in New Zealand, so I’m unsure about the US.
I remember this was one of the things I tried countless times as a kid. It never worked - the books showed these nice, clear crystals but all I ever got was a crust of dried salt and maybe one tiny crystal a few mm across.
I'm sure most of those "science for kids" book authors never tried a single one of their experiments.