Twenty years later (1884), Paul Vielle, a chemist working for the French government, experimented with the alcohol/ether solubility of nitrocellulose. He formed the wet mass into thin layers and partially dried them into flexible sheets. The residual alcohol/ether mixture acted as a plasticizer that helped prevent the granules from shattering. Cut into small flakes, the material burned inward from the surface. This property meant that the volume of gas produced decreased as the burning granules became smaller, which is a useful characteristic in propellants. Changing the dimensions of the granules resulted in different rates of energy release. Vielle’s discovery opened the door to modern propellants. His work was so effective that cut-sheet propellants are in limited use today.
A major disadvantage of Vielle’s method was dehydration. If the alcohol/ether plasticizer evaporates in storage, the rate of energy release increases. Dry granules could also break into smaller pieces, increasing surface area and thus the release rate.