How should colored fabrics be treated before washing?

Before washing colored fabrics, it is crucial to test for colorfastness. This step involves dampening a small, inconspicuous area of the fabric and applying a bit of water or rubbing it with a white cloth to see if any color transfers. If the color does not bleed, the fabric is considered colorfast and can be safely washed with others of similar colors. This practice helps prevent unintended dye transfer during the wash, which can lead to discoloration and staining of lighter colored garments.

The other options do not provide sufficient precaution. Washing all fabrics with bleach may damage or discolor them, as bleach can lighten or alter colors. Only separating bright colors implies that darker or pastel colors may be safe to wash together, which is not a reliable assumption. Washing all fabrics together without testing could lead to severe color bleeding, ruining multiple items. Therefore, testing for colorfastness is the ideal approach to ensure the longevity and appearance of colored fabrics post-washing.