The subtle flavor and satiny texture of butter make it one of the most important ingredients in sauce making. It contributes its own nuances to a sauce while gently amplifying and bringing into perspective the sauce’s primary flavors. Butter, if used in moderation, can be added to a sauce without diluting the sauce’s flavor or distorting its character.
Any wholesome salt-free butter can be used in sauce making with good if not excellent results, but some butters have different flavors and behave differently. As you use one kind of butter, its behavior will become familiar and you can more closely predict how it will act in specific preparations.