Which organic colloid swells in cold water and dissolves in hot water and is used in most photographic emulsions?

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Multiple Choice

Which organic colloid swells in cold water and dissolves in hot water and is used in most photographic emulsions?

Gelatin is an organic colloid that forms a thermoreversible gel. In cold water it swells by absorbing water into its network, and when heated the network breaks and it dissolves. This property is exactly what makes it the standard binder in most photographic emulsions: it can be prepared into a smooth, uniform coating that holds the silver halide grains together, then dissolved or reconstituted as needed during processing. The other terms don’t describe gelatin’s gel–water behavior or its role as the emulsion binder, so they don’t fit this description.

Gelatin is an organic colloid that forms a thermoreversible gel. In cold water it swells by absorbing water into its network, and when heated the network breaks and it dissolves. This property is exactly what makes it the standard binder in most photographic emulsions: it can be prepared into a smooth, uniform coating that holds the silver halide grains together, then dissolved or reconstituted as needed during processing. The other terms don’t describe gelatin’s gel–water behavior or its role as the emulsion binder, so they don’t fit this description.

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