Rock Salt

The salt used in making homemade ice cream is rock salt. It is a coarse salt and should be used instead of regular table salt.

The amount of the ice and rock salt you use varies according to the ambient air temperature. Do not increase salt usage until you have churned the freezer for at least 10 minutes. After 10 minutes, you should notice the cream becoming firmer. If too much salt is used, the result will be excessive freezing to the extent that a crust of frozen cream will form on the inside edge of the can while the middle will remain liquid. If this occurs, allow the brine to warm up by taking a scoop of salt and ice out of the bucket and then decrease the amount of salt added when you next add more ice.

We need a salt concentration, or a ratio of 5 cups of ice to 1 cup of salt. This will keep our brine temperature constant at 8 to 12 degrees Fahrenheit. This will give us the rapid cooling and freezing that is essential to making smooth, creamy ice cream.

Freezing time should not be too slow or too fast. A greater amount of salt will melt the ice faster causing the ice cream to freeze faster. Freezing too quickly will not allow for sufficient agitation and will produce a coarse texture. An extended period of freezing causes a spongy, buttery texture.

Use a glass or plastic measuring cup for rock salt, as salt may pit a metal container.

The freezing takes place in the White Mountain® ice cream maker by using rock salt and ice as a refrigerant. Rock salt causes ice to melt quicker by lowering its melting point. The "brine solution" or liquid that forms in the wooden bucket absorbs heat from the ice cream mix and gradually lowers the temperature of the mix until it begins to freeze.

If no salt was added to the ice, it would melt at 32 degrees Fahrenheit and eventually the ice water and ice cream mix would stay at 32 degrees. Since Ice cream will not begin to freeze until its temperature falls below 27 degrees, we need to add salt and lower the melting point of the ice.