What does gelatin emulsion do?

187 1 year, a British doctor, leach maddox (1816 ~1902), introduced it in the British photography magazine, prepared gelatin emulsion containing silver bromide, coated it on a glass plate while it was hot, and then dried it with chemicals. When washing, the emulsion will expand properly to facilitate the reaction between developer and fixer. At the same time, maddox also completely released his gelatin emulsion formula.

Maddox's invention aroused great interest. According to maddox's method, it is found that in the process of preparing emulsion, prolonging the heating time can greatly improve the sensitivity of emulsion, and the silver bromide photographic film made by this method can be stored for a long time after drying. So photographers don't need to prepare and apply emulsion before each shooting, they can buy a box of ready-made dry plates in the store.