In Ayurveda, some medicines of inorganic origin (mineral and metallic) are prepared using a special method, Kupi-pakva. Medicines prepared using this process are known as Kupipakwa Rasayan. The example of such medicine include Makardhwaj, Malla-sindoor, Rasa-sindur, Sameer pannag rasa, Shila sindur, Talasindura, Rasakarpura, Rasapushpa, Swarna Vanga etc. Kupi-pakwa is unique and highly evolved pharmaceutical preparation of medicines inside a Kanch-kupi or glass bottle. Such medicines are difficult to prepare and require proper control of temperature, heat, duration of processing and other factors to get the desired result.
For preparing Kupi-pakwa medicines, first Kupi or glass bottle is prepared. This is done by selecting a bottle, wrapping it with mud smeared cloth in seven layers. The layers are allowed to dry. Then Kupi is filled one third with required ingredients. Purified Parad/mercury and Gandhak/sulphur are mostly used in preparation of various Kupipakwa Rasayanas. This Kupi is buried at the centre part of the valuka yantra (gradual heating immersion in sand bath) to get uniform temperature. Then the processing is done by gradually heating (Mridu/mild, Madhya/moderate and Teevra/intense agni) for specified period of time. The temperature is carefully controlled. The fumes and flames are carefully observed and cork is placed on bottle at appropriate time. Then few tests are done to confirm the completion of process. Finally the Kupi is allowed to cool and is removed from apparatus. This is broken by a special technique to separate the Kanthastha (at neck of bottle) and Talastha (bottom part of bottle/kupi) parts of the resultant product. Some Kupipakwa Rasayan like Mallasindoor, Poornachandrodaya Makardhwaj are collected from neck (Kanthastha) while some others like Rasa sindoor, Sameer pannag Rassa etc. are collected from bottom part (Talastha).