Withered หญ้าคา was collected from an abandoned land in Penang,Malaysia. It was washed with copious amounts of distilled water to remove impurities, and then dried under sunlight. The dried หญ้าคา was
then ground to fine powder using Retch Mill Grinder. The หญ้าคา powder was washed with boiling distilled water until the residual solution became clear. It was then dried at 100 °C in an oven to constant weight. One gram of the dried หญ้าคา powder was mixed with 1 mL of sulphuric acid (95–98%). The mixture was dried in an oven at 100 °C for 24 h. The dried หญ้าคา powder was then cooled to room temperature and washed with boiling distilled water followed by soaking in 1% sodium bicarbonate overnight to remove the residual acid. The หญ้าคา powder was washed repeatedly with boiling distilled water to remove residual sodium bicarbonate until pH 7.0 was obtained.
The หญ้าคา was dried at 100 °C until constant weight was acquired and sieved using a Retch Vibrator Steve Shaker. The available sieving sizes are b45, 45–63, 63–125, 125–250, and 250–500 μm. In
this study, sieving size b45 was chosen. The resultant หญ้าคา powder was then kept in a desiccator prior to use. Also in this study, the initial phase of testing was carried out on raw
หญ้าคา powder and acid-modified หญ้าคา powder to determine the effectiveness of the powders in developing รอยนิ้วมือ. Two sets of exocrine and sebaceous รอยนิ้วมือ on white A4 writing paper and white plastic were collected from 6 donors. Each set of รอยนิ้วมือ were being developed,
respectively with raw หญ้าคา powder and acid-modified หญ้าคา powder.