Here is my attempt at making Matsuyani, a Japanese hard pitch for repousse. The recipe comes from Ford Hallam, who was kind enough to post this, years ago on the Carving Path Forum. His ingredients are:

750 grams of Pine Rosin (Pine resin boiled down).
1,000 grams Plaster of Paris
50 grams Vegetable Oil
1 tsp Charcoal powder

Finding the pine sap/resin is time consuming. I think I covered 14 miles of forest. If you can find one struck by lightning, that's your best shot. After collecting, boil down to convert the sap/resin to pine rosin. Be warned, this stuff wants to boil over and it produces turpentine fumes. Do Not catch on fire. If you burn the pitch, it loses some of its' properties, only use a heat gun. Add all ingredients, cook down and pour into your repousse bowl of choice. The bowl in the video, I made years ago from 1" plate, welded together. Weighs a ton.

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