Abstract: The present invention is drawn to a method for de-staining a substrate that is stained with a dye by bringing the substrate into contact with a de-staining composition and absorbing the dye from the substrate with the de-staining composition, wherein the de-staining composition is a charcoal or ion-exchange resin absorbent incorporated in a semi-solid matrix which is a polyacrylamide or agar gel. With the method of the invention a stained substrate may be stained and de-stained in a single step. The present invention is further drawn to an apparatus for performing the method of de-staining the substrate.