For many white linens, especially in places like hotels, hospitals, and guesthouses, yellowing after washing is a common issue. There are many possible reasons for this discoloration. For users of washing equipment, without understanding these reasons, they won't know how to deal with it. Even with high-performance industrial washing machines, if the cause of yellowing isn't addressed, the problem persists. To assist laundry workers in handling this situation better, this article presents some viewpoints.

The primary reasons for yellowing lie in the application and selection of detergents, the quality of water chosen for washing, and the washing process itself. Among the various detergents available, surfactants and other additives are essential for their effectiveness. However, some manufacturers may opt for cheaper additives to cut costs, which can lead to yellowing of the fabric. To address this, it's advisable to choose high-quality detergents from reputable sources.

Apart from detergent issues, some laundries use hard water, while others opt for treated softened water. Yellowing typically occurs more frequently in laundries using hard water due to the presence of inorganic salt ions, which can affect the fabric. Chemical reactions between these ions and the fabric or detergent in hard water can lead to yellowing. To mitigate this, water treatment is recommended. Adding a suitable amount of water softener during the main wash can effectively address this issue.

Additionally, when washing yellowed linens in industrial washing machines, adding optical brighteners can help remove accumulated dirt from the fabric. For stubborn cases, adding oxalic acid, sodium hydrosulfite, or using reducing agent solutions like insurance powder or sodium hydrosulfite can restore the fabric's whiteness. For users of washing machinery, mastering more knowledge is essential to ensure higher work efficiency. Mere machine operation skills are insufficient for achieving perfect washing results.