Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: What is the smallest quantity of gravy/sauce that this separator will work on? Will it work on half a cup?
Document: Great product. It works! And it is large enough to not have to do more than one separation of a sauce. In fact it's size, being large (1L), is the only thing that could be negative about it if you are short of room since it is only a one purpose tool. In a pinch it could be used for a measuring cup also but the markings are not easy to see.
this fat separator is great! the strainer on top is a nice feature and the measuring cup part holds a lot of gravy.
Yes, it works well as a gravy/fat separator. However, it's also great for straining all sorts of sauces (just pour through the top) and is wonderful to have on hand as an extra measuring cup for large quantities of liquid. I wouldn't recommend it as a dry measuring cup due to the shape, but it works perfectly for what it is.
Whoever invented the fat-free gravy separator was a genius, hands down. I love this one because of it's large 4-cup capacity with measurements on the side plus the wide perforated lid that allows you to easily strain out the larger bits of meat or skin from the drippings. This is a quality product and I just love it.
The Trudeau fat separator is vastly superior to the common cup shaped versions. It has a large capacity, an excellent strainer and  because of its shape is very stable--important when pouring hot gravy from a roasting pan. Unlike cup shaped separators the fat rises to the top immediately and fat-free juices can be poured off without waiting. Useful for gravy, soups, pot roast juices and anything that needs the fat removed.
I was not that crazy about it but it was ok it kind of work some for the gravy ok
I bought this to cut out the fat when using meat juices for sauces or gravy like turkey or chicken gravy, odobo/chicken cooked in soy sauce, etc.
This is my second fat separator from Trudeau. America's Test Kitchen is right when they say it's the best. A large top allows for easy transfer from pot to separator. The strainer makes easy work of removing veggies from your sauces. I highly recommend this product!
The title says it all. Highly effective and probably the only one you might need. I will say that for most people, the smaller sized separator would work just fine. I bought this one because sometimes I make braises that have copious amounts of liquid. Great product.
It does a great job of separating the fat from the sauce but I've developed a crack on the bottom (and it leaks) and I think it's from putting it in the dishwasher. I've tried handwashing it but fat and plastic are tough to clean without super hot water. I had a different brand fat separator before and it was glass. I broke that one.
Answer: I think it work but perhaps wouldn't work at its best.  A half cup basically covers the bottom with little room for the two layers to separate.  Think u would be better off letting 1/2 cup sit in whatever vessel you have and then skim off the fat layer (refrigeration helps) ...and use this for 1 cup plus quantities.  Works great...use it all the time.