| 摘要 |
<p>An impregnated fabric material comprising a fabric substrate to which has been bonded an active cationic impregnant characterized in that there has also been applied to the substrate an anionic indicator dye in combination with a further cationic component, and in that the dye bonds to the further cationic component more readily than to the substrate and that the further cationic component competes with the impregnant for bonding to the dye. In the case of a wiping cloth, when the dye, which can act as an indicator, has been removed to indicate exhaustion of the active component, enough active component in fact remains on the cloth to provide a safety margin.</p> |
