Ayurvedic Thaila medicinal oil decoctions: sesame oil base, copper boiling, and foam tests?

Compounding classical Ayurvedic medicated oils (Thaila) requires extracting active herbal phytoconstituents into a lipid base (typically cold-pressed sesame oil / Tala Thel or coconut oil). The formulation combines one part herbal paste (Kalka), four parts oil (Sneha), and sixteen parts aqueous herbal decoction (Kwatha). The mixture is simmered slowly in a wide copper cauldron (Thambiliya) over gentle firewood heat. As water evaporates, the oil undergoes classical Paka stages: Mridu Paka (soft paste), Madhyama Paka (optimal medium paste), and Khara Paka (hard paste). The pharmacist tests readiness by rolling a small ball of herbal paste between fingers: it must roll cleanly without sticking, and dropping paste onto an open flame must produce zero crackling (confirming complete water evaporation).