11.   Skim foam from top.

12.   Skim the foam that rises to the top, being careful not to skim the oil.

13.   Skim foam if necessary.

14.   Skim foam regularly from surface.

15.   Skim any foam that forms during the cooking process.

16.   Skim the foam off the surface, then pour off the clear liquid, which is the clarified butter.

17.   Strain through a fine sieve and skim any foam on the surface.

18.   Recent arrival Heineken seeks to skim the foam off the top of the market.