Why pick butter? Sure you could use it. But cow pie juice would work too. A spit patch is cheaper, beeswax/tallow combinations are traditional, in combination or separately. Tallow is animal fat, you can get a pound of absolutly pure pork lard at the store for cheap, the butcher will give you probably for free, edible quality carcass fat trim to render,household vegetable oil is commonly used too. Why, I'm wondering? What's up? Wonky