Roux

What ratio of fat to flour should roux be when used to make large quantities of soups or cream sauce and how much roux should be used for each gallon to achieve the desired thickness? When I make large amounts, it either turns out too thick or not thick enough and I would like to have some type of guidance to avoid this. Thanx in advance.

[Sodaro]

Sounds like a question on a culinary school test.

The classic rule of thumb I was taught and seems to work like a charm is equal parts (by weight) fat and flour and 1# of roux per gallon of liquid.

To make roux, equal parts of fat and flour.

To thicken a liquid, a pound of roux thickens a gallon of liquid the nape stage.

Thanx for the help, and yes, I did have that question in culinary school. The thing is that I did know the ratio, but the amount per gallon was "iffy". Now I can print this out and show it to my chef (who despises culinary school graduates). He believes in doing everything by sight and throws all kinds of remarks at me when I want to measure out things...but no remarks when it comes out perfect (but that's another topic)!! Sodaro, we both are from the western suburbs of Chicago, so I'm interested to hear where you work if you'd like to share it!