Old-fashioned ice-cream makers, such as those made by White Mountain, require a combination of ice and rock salt to form a refrigerant that quickly freezes the ice-cream custard mixture. The ideal ratio is five cups ice to one cup salt. Rock salt causes the ice to melt quickly, resulting in a brine that will maintain a temperature of 8 degrees to 12 degrees. This salty solution rapidly absorbs the heat from the ice-cream mixture, which will start to freeze at 27 degrees. For best results, chill the ice-cream mixture overnight before churning; this produces ice cream with the most volume and creamiest texture.
Consult the instructions that came with your machine; if you no longer have them or are using an antique mechanism, follow these steps for ice cream that's just the way you like it.
Homemade Ice Cream How-To
1. Prepare ice: Place a five-pound bag of ice in a heavy cloth bag, and break it into pieces using a kitchen mallet or a hammer. The smaller the pieces, the more quickly it will melt.
2. Prepare tub: Place the ice-cream maker's stainless-steel canister in the wooden tub. Insert the dasher in the can, making sure the dasher's socket rests on the protrusion in the center of the canister bottom.
3. Pour the chilled ice-cream mixture into the canister; do not fill more than halfway. Place the lid on the canister, and turn dasher handle with your fingers until it rotates freely. Attach the turning mechanism, gently pushing the thumb latch down until the unit is secure.
4. Fill wooden tub with ice until it reaches the top of canister. Crank 2 minutes, and then pour 2 cups rock salt over top of ice (assuming you've used 10 cups of ice). When the ice melts down 2 to 3 inches, add more, again filling to top of canister; add 2 more cups salt. Continue churning, adding ice and salt as needed, until handle becomes difficult to crank, 10 to 25 minutes. At this point, you'll have soft ice cream.
5. For firmer ice cream, remove dasher, and scrape ice cream back into canister. Place a sheet of wax paper on top of ice cream in canister, and replace lid. Plug the hole in the cover with a cork stopper. Drain off brine from wooden tub, and repack with ice and salt, again in a 5-to-1 ratio. Cover with heavy cloth or burlap bag, and let stand until ice cream is desired consistency.
Note: The amount of ice and salt you use will depend on the ambient air temperature. After churning for 10 minutes, check the ice cream; it should be almost firm. If there is a crust of frozen cream on the inside of the canister, allow the brine solution to warm up slightly, and then decrease the amount of salt.