This is a very fine extraction method, which is rarely used now because it takes a lot of time.

First, the petals rinsed with clear water are laid on a glass plate coated with animal fat or plant fat, covered with a wooden frame, then the framed glass plates covered with petals are stacked one by one, and finally the stacked wooden frame glass plates are placed in the sun to let the heat of the sun release the essence of the petals.

Turn the glass plate over every two days. Dump the yellow and withered petals, then spread flowers, and repeat this process until the oil coated on the glass is fully absorbed and the essential oil is released. At this time, these fats are called balsam. After that, the oil in the balsam was washed away with volatile pure alcohol to obtain refined and expensive clean oil.