Gelatins of three densities are poured into a large pan. Gelatin I is a diluted and soft gelatin, Gelatin II is a regular, firm gelatin, and Gelatin III is an extra firm, rubbery gelatin. A pulse in the shape of a trough is generated in III. A pulse (1/2 wavelength) is generated that extends exactly 1 color-band, that is, over 1 section of gelatin. In other words, the first pulse generated extends from the back end of the pan to the red/green boundary.

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