Two partners try to dissolve a partnership that owns an asset of ambiguous value, where the value is determined ex post by a draw from an Ellsberg urn. In a within-subject experiment, subjects make decisions in three different bargaining mechanisms: unstructured bargaining, the Texas shoot-out, and a K + 1 auction. We find that the K + 1 auction is the most efficient mechanism, which is in line with theory. Free format bargaining yields a surprising number of disagreements, which are not usually observed when the partnership has a certain or risky value.