Well you got me!
Don;t know when Morton started putting any additional chemicals in Kosher salt?
Salt is salt but it's the different crystal structure and/or any impurities that give rise to the different tastes perceived by some. Once it's mixed or added to food, there is no difference.
I use Cary Pickling & Canning salt for most additions in food prep because it's cheap. Nothing but salt, I just re-read the label. It has very fine crystals similar to table salt.
Neither Morton Kosher or Diamond Kosher specify they are for canning.
The only affect of Iodine and any anti-caking agent would be on color.
I use Morton Kosher for most surface addition over Diamond because I prefer the texture over Diamond.
For a real salt kick on buttered fresh baked bread(we use unsalted butter), I have Fleur de Sel It's large crystals give you a kick. For seasoning roasts for the BBQ and oven, it's Baleine brand Sel De Mer Gros(coarse), the crystals are very large and do not dissipate in dry roasting. It does have Sodium Iodide so it is not used as an ingredient in my cooking., just a surface agent.
There are others but I rarely use them including the aforementioned Morton Seal Salt which I have an unopened can of!
Table salt has very fine crystals and I didn't know you could actually purchase non-iodized table salt but I just checked the Morton website and it does exist!
So I suspect that somewhere along the way Morton added the Prussiate and the word is not yet widely known nor is the word on non-iodized table salt..I assume the Calcium silicate is in the non-iodized.
If you don't want any additives, switch to salt such as Cary.
Frankly we have not used table salt for decades, I just don't like it's fine crystals and I still prefer Morton Kosher for it's grain size and density over Diamond.
We use none of the colored salts because I don't know whether the impurities are measured.
I long asked the importer of the then popular pink Himalayan salt and salt blocks if an analysis had been conducted for impuities and never received a reply. Heavy metals such as are analyzed for in some dried sea weed products are a concern of mine.
I'll stick to Cary for canning, curing and preservation.
Morton kosher for most salt addition in cooking.
Sel De Mer Gros for dry roasting and Fleur de Sel for bread and butter.-Richard