Regarding raw and boiled linseed oils. A few years ago I did an informal test of the drying rates of these oils, rubbing a smear on a piece of glass. I am sure steel would work as well. In the unadultered state (right from the can) the boiled oil dries a lot faster and harder. Mixed about 50-50 with either Japan drier or cobalt drier (Grunbacher) the boiled oil dried harder and faster. As I understand it, the boiled oil is not boiled but rather treated with chemical driers. A friend once did boil some oil; he told me "he damn near burned his house down". He does not do that anymore. Any rags with linseed oil on them are the dreaded "oily rags" which can sponteaneously ignite, and should be diposed of outside. Again in my experience, I have found the Artists oil to be raw oil, and I use boiled oil for a final finish, but find raw oil is better at a rubbing off.
I have heard the cup grease story also; I think the cup grease was the old grease used on wooden wagon wheel bearings, I don't know it's makeup but I doubt it was a petroleum product. And I have never tried it, and I doubt a current grease would do it, but one could try.
