I've not tried Shapeway's "frosted (ultra) detail" material, but IIRC, it involves a wax support matrix that sometimes ends up leaving a thick residual coating on the parts. Supposedly it can be scrubbed off with the right solvent, but I cannot remember what solvent it was.
I remember when they debuted the material they had a lot of problems with misprints and the material not curing properly and suchlike. I've never been able to get a straight answer as to whether or not that stuff was ever really sorted out (and the disclaimers were still in place, last I checked), so I don't trust it. TBH, none of the materials they currently offer seem quite model grade to me. They all have resolution, cost, texture, or durability problems (usually a combo of these) that prevent them from being final materials. Even for casting masters they require a lot of work to be presentable.
There are machines/processes/materials that can produce final or casting grade results, but Shapeways doesn't offer them.