The effect of chlorine concentration in laundry solutions on the life of the laundered fabrics is signalled by a chlorine concentration indicator swatch, in which contrastingly hued dyes, including one whose chlorine resistance is measurably stronger than the other, are combined to dye fabric test swatches an initial color. Including such fabric test swatches in chlorine-containing laundry solutions causes visually discernable changes in the hues of the swatches as the bleaching action progressively subtracts those dyes of lesser resistance. Chlorine concentration which, if excessive, seriously impairs laundered fabrics, may be determined by visually inspecting the swatches.