Check if your bucket is large enough by putting both water bottles in it while it’s still empty. You’ll be adding the water bottles after you create the salt and ice water mixture.
If it hasn’t dropped below that temperature, add 1 cup (300 g) of salt and mix.
Don’t use tap water. Ice crystals can form around impurities in tap water, which will ruin the supercooling process.
If the water has frozen, let the bottle thaw before trying again from the beginning. [7] X Research source
The motion of unscrewing the cap on the second bottle is enough to set off the ice crystals. [9] X Research source If the water doesn’t freeze, tap it more firmly. If that does not work, return it to the ice water mixture and let it cool for another 30 minutes before trying again. [10] X Research source
