For many white linens, especially in places like hotels, hospitals, and guesthouses, there is often a yellowing issue after washing. There are various possible causes for this situation. If users of washing equipment do not understand these causes, they will not know how to address the issue. Even the best-performing industrial washing machines cannot resolve yellowing without the right knowledge and approach. To assist laundry workers in better handling this issue, this article presents some viewpoints.

The primary causes of yellowing are related to the application and selection of detergents, the quality of the water used for washing, and the washing processes themselves. Most detergents require surfactants and other additives to work effectively. However, to reduce production costs, some manufacturers may opt for inferior additives as substitutes. One cause of yellowing is the presence of these substitute additives. To improve this situation, it is recommended to choose high-quality, reputable detergents.

Another issue is the type of water used for washing. Some laundry facilities use hard water, while more professional ones use softened water. Yellowing often occurs in facilities using hard water, which contains inorganic ions that can affect the linens. These ions can react chemically with the linens or detergents, leading to yellowing. To address this, it is necessary to treat the water. Adding an appropriate amount of water softener during the main wash can effectively improve this situation.

Besides improving detergent quality and water softness, adding oxygen bleach powder during the washing process can help remove some of the residual dirt from the linens. For more stubborn yellowing, adding oxalic acid, sodium bisulfite, or soaking in reducing agents like sodium dithionite or sodium thiosulfate can restore the fabric's original whiteness.

For users of washing equipment, only by mastering more knowledge can they ensure higher work efficiency. Simply knowing how to operate the machine is not enough to achieve perfect washing results.