In this the herb is crushed/grinded and soaked overnight in hot water and strained early morning. This liquid is called Churna drava or Phanta or Hot infusion. The essential part (saara bhaaga) of herbs is absorbed easily and fastly in the hot water. Also, those substances whose essential part is completely obtained neither in Hima Kalpana nor in kwatha Kalpana (may be destroyed in it). Hence, it is considered the best kalpana.
The coarsely powdered herbs are kept in water overnight and rubbed with hands in morning and strained. The liquid obtained is called Hima kalpana or cold infusion in ayurveda. The fragrant and shita virya dravya on heating converts into Ushana virya and the fragrant and volatile oils are faded away and thus, such substances should not be heated and in order to receive their essential part (saara bhaaga) hima Kalpana is prepared.