I added a little bluing when washing my white shirts to prevent them from yellowing.

bluing 是由动词 blue（使变蓝）加上名词后缀 -ing 构成的名词，指"蓝漂剂"或"蓝色漂白剂"。这种物质含有蓝色染料，用于中和白色衣物上的黄色色调，使衣物看起来更白。