Second, the sublimation of pellets on impact helps to lift paint from the surrounding substrate. First generation systems were slow but recent modifications have improved the speed. CO2 blasting is gentle on substrates but, as you might guess, it is not cheap. This relatively inexpensive media was also developed for aircraft paint stripping. The crystalline wheat starch used in this system can be reused and actually becomes more aggressive as it breaks down.
Wheat starch is very forgiving of error and is easy on substrates.
Crystalline wheat starch molecules are different from the naturally occurring polymer so explosion potential is not a problem. Wheat starch media has also been successfully used in fluidized beds for parts cleaning. These unusual media are used, among other things, to clean carbon deposits from engine parts. Ground walnut shells are gentle on the substrate and inexpensive, dependent, of course, on the futures market for walnut shells. Peanut shells and ground corn cobs are also used as blast media.