Cream is one of two by products of unhomogenized milk. Allowed to sit, the cream rises to the top while the equivalant of skimmed milk goes to the bottom. On the market today are pasteurized and ultra pasteurized cream. While the ultra pasteurized cream has a longer shelf life due to being heated to up to 300 degrees briefly, some feel it doesn't whip as well. I don't think it tastes as fresh as pasteurized cream so we never used it.
There are a good number of different types of cream today. They are classified by the amount of milk fat in them. In descending order they are:
40% or Heavy Cream - contains 40 percent milkfat
Whipping Cream - 30 to 36 percent milkfat
Light cream or coffee cream - between 18 ad 30 percent milk fat but is usually closer 20 percent.
Half and Half is a mixture of ½ milk and ½ cream. We did not stock it at the bakery. We simply made it by combining cream and milk when we needed it.
Cream is highly perishable and needs to be refrigerated and used within the "use by" date. We had a spell on several occasions at the bakery where the cream was spoiled before the date expired. It became a practice for us to shake the cream, open it and smell it before we used it. Fortunately, our supplier always took back any cream that had turned.
David Lebovitz, www.davidlebovitz.com wrote a blog on freezing cream, thawing it and using it as just bought. Haven't tried that yet but it intrigues me.
I don't use anything but 40% or heavy cream for whipping. We used it to finish some of the cakes at the bakery and, other than sweetening it, never used a stabilizer. It held beautifully even when frozen and thawed with no leaking or deterioration.
I can't imagine anyone who makes pastries that hasn't over-whipped cream at some time. We certainly did. In fact, that is how this fix came about. I had a wonderful employee, Dina, who over-whipped a fair amount of it one time. Knowing this was not going to put her on my favorite person of the day list, she came up with a way to salvage it. Simply pour more cream in, reduce the speed to low to incorporate it and then raise it to finish beating to the desired consistency. I still use this technique today. In fact, I over-whipped some the other day. That's what reminded me you all need to know how to fix over-whipped cream. The amount of cream you need to add depends upon how over-whipped it is. A general rule is to add one fourth to one third the amount you started with. Add more as necessary.
The only time this doesn't work is if you turn it into butter. When I worked at the Hyatt briefly, I managed to turn 16 quarts of whipped cream into butter. The bakery was so large, I put the cream in a 60 quart mixer and went to the other end of the bakery to work on something while the cream was whipping. All of a sudden I heard Gina exclaim, "Oh no!!!!!" Every head whipped around to look at the whey being thrown out of the bowl into the air as butter was churning away. Just about that time the executive chef walked by looking none to happy. "Just throw it out and start again", he said, turning to me. Thinking quickly, Gina said, "No, put it in the cooler and we can use it up in other stuff." It took me no time to strain it, get it into a large container and put a sign on it that said, "Helen's Butter". We all laughed so hard and chef loves telling the story. As a side note, we did use it all. But they still remember "Helen's Butter"
Basic Recipe
1 cup 40% or heavy cream
⅓ cup powdered sugar (40 grams or 1 ½ ounces)
1 teaspoon of vanilla or other flavoring, optional
Put all the ingredients in a mixing bowl fitted with a whisk. Beat slowly at first until it starts to thicken and then it can be raised. Use as desired.
There are different stages of cream as it is whipped.
Chantilly Cream is barely thick and leaves a trail in the cream. It will not hold a shape.
Soft Peak - When the cream is picked up on a whisk the peak of the cream falls over.Stiff - the cream is very tight and can withstand piping and being used as a frosting.
Over-Whipped - this goes from looking yellow and curdled to "you have just made butter" where the whey separates from the cream. 
Salvaged Whipped Cream - returns to white and is smooth and useable again.
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Kim says
Helen, early in my marriage my mother in law gave me the task of whipping the cream for a dessert while she finished up another dish. I soon asked her what the lumps were in her cream. She smiled and with grace told me,
"you've turned it into butter". I was so embarrassed! I have been paranoid about whipping ever since and I never leave it alone!
hfletcher says
That's a very good point. As you can see from my article, I managed to turn 16 QUARTS of cream into butter. But for small amounts it whips up fairly fast, so staying with it is a good idea. Thanks for the comment.
Eva Forson says
Helen, you are a real pro. Thank you so much for sharing your knowledge. Eva
hfletcher says
Thanks Eva and thanks for reading.
Mary Moses says
Just want to say THANK YOU for sharing all your wonderful bakery knowledge. Reading all your great tips helps me feel that I have more control in my own kitchen. Your posts are always thoughtfully thorough. Who does your photos -- your husband or your son? They do a great job of clearly illustrating your text. Thanks again! Mary.
hfletcher says
Dear Mary: Thank you for your comment. When I first started baking professionally, there was no help anywhere. Since I have closed the bakery I enjoy sharing what I learned. It is wonderful knowing it helps others that love to bake. My husband is a retired professional who never did food before who supplies the great graphics that help so much.