I use a metal bowl. If you really want to remove the oils, wash with vinegar before use - I don't usually bother, but did when whipping egg whites for a wedding

I use a metal bowl. If you really want to remove the oils, wash with vinegar before use - I don't usually bother, but did when whipping egg whites for a wedding cake. IIRC, copper stabilizes the egg whites so they stay foamy for a decent time, but they don't always get as stiff as they do in a glass or metal bowl and it is definitely harder to overbeat. To be fair, if you are whipping by hand, you probably are in no danger of this. And for those that don't know, folks usually use something like cream of tartar in eggs to do a similar stabilizing, though you still get stiff foam.