At photo studio that still use roll film usually find burned photo paper. Don't throw it away, it can be good painting. Follow this tutorial below.
1. Burned Photo Paper ( 1 piece)
2. Bayclean whitening (10 cc)
3. Water (at sufficiently)
4. Cotton (at sufficiently)
5. Paint Pen (1 piece)
6. Nitrat (HNO3) (10cc)
a. Mix HNO3 with water
b. Spread it on burned photo paper
c. Paint with your own creativitiy.
d. Wait until it dry