Gee. a butter room. somehow i doubt anyone has done that before. i would think you would need a super glossy material overlayed on a nice reflective one for sharper highlights. i would recomend playing with the egz carpaint material since it has both those properties
yeah I think it would be pretty hard w/out SSS, because of the nature of the material…
I would say, the key is observation of the material “maped” in a similar way in the real world..
take a good chunk of butter and slap it on a board..say 2feet by 2 feet or somethink like that, and put that in different ligthing conditions and see how it reacts…that should give you much more of an idea on how to go about the CG version of the mat…but I think daelf is right…mostly high specualar reflections and some soft SSS…
I think the experiment in real life of spreading that on a good size board should give you some good ideas on the material’s propreties as a large surface, rather then just looking at it packaged as when bought from the store.
I’d try with standard material with a slight amount of self luminance. On the other hand, you could maybe get away with glossy refractive material without IOR=1 and without translucency/fog