The absorption technique is based on the ability of animal fat to naturally absorb odours. Depending on how well the plant matter withstands heat, this process can be conducted at either hot or cold temperatures.
Hot absorption or maceration consists of steeping flowers or other scent-bearing materials in previously heated fats or oils. This mixture is then filtered through fabric to obtain scented unguents. These perfumed pomades are then mechanically washed in alcohol, after which the alcohol, now perfumed, is separated from the fat. This technique, practised since Antiquity, has been complemented over the centuries by the development of other extraction methods.
Since fragile flowers such as jasmine, tuberose and daffodil cannot withstand heat, the technique of cold absorption was developed. This technique was very common in the Grasse region until the first half of the 20th century. Cold absorption consists of spreading a layer of cold odourless fat onto sheets of glass held in frames; this fat is then covered with flowers that are regularly replaced with fresh ones until the fat is saturated with fragrance. These perfumed pomades can either be used to manufacture cosmetic products or mechanically washed in alcohol to eliminate the fat, after which the alcohol is evaporated to obtain absolute.