I recently stumbled across this article from 2017 The Humble Garnish that does a fantastic job of testing a variety of "at home" clear ice making molds.
The author uses a couple of directional freezing methods, but also puts boiled water, bottled water, and purified water to the test, clearly showing that directional freezing is the only real way to get clear ice. This is illustrated in the article where BLK mineral water is used to show how, through directional freezing, all of the minerals are pushed out. Here's a photo from the article:
To summarize the results, the single most important factor in attaining clear ice is that it be done through slow directional freezing. Water type and temperature will have a small impact on clarity, but the greatest impact it will have is that poor quality water will impart any flavors into the drink as it melts. The two obvious winners for attaining clear ice were the True Cubes mold and the “cooler method” since they both employed directional freezing, allowing the impurities to be easily discarded. For either of these methods, the choice in water type or preparation method had little impact on the resulting ice clarity, but will have a flavor impact as it melts. To make clear ice at home, the only worthwhile methods will incorporate directional freezing.
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ClearIce.Life is maintained by Trapper Markelz in pursuit of elevated cocktail experiences at home, and with friends.
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