Hi Michael, the loose option seems like a good idea. However, now I no longer can use the blend feature to create a closed surface..

/Lars

Edit: just read the help file: Note that if you have independent curve objects overlapping your surface edges (for instance some of the original curves used to build the surface), it is easy for those curve objects to get selected when you click instead of selecting the edge of the surface. It may be necessary to delete or hide these original curves so that the edge of the surface object can be selected instead, that is an easy problem to run into when using Blend.

Hiding those original curves and then blending the edges of the surface did the trick.