Chilling? How can I quantify that?

This question seems slightly ridiculous, but I'm a noob, so bear with me.

In this oft-referred to recipe for making ice cream, what does "chill-completely" mean exactly? Is there a measurable temperature or timeframe I am looking at? Should it just be lukewarm or coldish? Do I stir it to make it cold all the way through?

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By the way, the methods described below tell you how to accomplish it, the answer to "how can I quantify that?" is by using a thermometer. If you get your mix to 0C or 32F then it won't be frozen, but it will be on the verge. Thermometers are your friends. – Doug Johnson-Cookloose Jan 12 '11 at 23:07

"Completely" definitely isn't a standardized term; however, since we're talking about making ice cream here, the correct answer is going to be "as cold as possible without freezing".

When making ice cream, it's important to get the mixture as cold as possible before you freeze it, especially if you're not using an ice cream machine, so that you give it as little time as possible for ice crystals to form. If large ice crystals form, then you won't have ice cream, you'll have ice.

So get it all the way down to refrigerator temperature and work quickly when you take it back out of the fridge. It'll be quicker and easier if you chill the bowl or receptacle first.

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You can even chill it a bit further in the freezer to take it colder than the high 30s F of a good fridge. Ice cream won't freeze until you are below the freezing temperature of water, so you have some leeway. The goal, as stated, is to have the mix be as cold as possible while not beginning to freeze, then to freeze it as rapidly as possible so as to form tiny rather than large ice crystals. And if you chanced to forget it in the freezer and it began to freeze, take it out and stir it until the crystals melt. That would be as cold as you could get it. – Doug Johnson-Cookloose Jan 12 '11 at 20:58
The other common approach is an ice-water bath; that'll hold your bowl right at the freezing point, so what's inside can't actually freeze, but will get nice and cold. – Jefromi Jan 12 '11 at 21:01