A water-soluble, non-crystalline substance comprising solid particles of a very small size (typically 0.00005:0.0000001 cm) dispersed in a solid, liquid, or gaseous medium. The particles themselves can be large protein molecules, or aggregates of other substances. Common examples include gelatin, glue, and albumen. Colloids are used as vehicles in emulsions used for stencils in screen printing, and the application of bichromate renders them photosensitive.
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