Baby Diaper
Baby Pull Up Pants
Adult Diaper
Sanitary Napkin
Wet Wipes
Tissues Paper
Disposable Cotton Soft Towel
Pet Diaper
What Causes Yellowing on the Surface of Sanitary Napkins? Is It a Quality Problem?
Hot melt adhesive inside the core can turn slightly yellow over time
The core layers of a sanitary napkin are bonded with hot melt adhesive. When applied at high temperature, the adhesive is transparent. But after a few months of storage, natural aging of the adhesive may cause it to develop a very pale cream yellow colour. If the yellowing is even, very light, and only in the core area, it is normal and does not affect absorbency or safety. Almost all brands have this characteristic to some degree; the difference is only in how noticeable it is.
SAP oxidation – irregular small yellow spots
Super absorbent polymer (SAP) exposed to air for a long time can oxidise slightly, forming pin head sized pale yellow particles. This usually happens with simple packaging (multiple pads in one bag) after the bag has been opened, because there is no individual wrapping to protect each pad. If individually wrapped pads show yellow spots before opening, it suggests either poor seal integrity or excessively long storage. A small amount of oxidised SAP does not harm absorbency, but customers find it unpleasant. That is why we always recommend individual wrapping – to avoid this problem.
■ Nonwoven top sheet dampness yellowing – a storage issue
If sanitary napkins are stored in a humid environment (e.g., the bottom of a shipping container or a basement), the nonwoven fibres absorb moisture, become soft, and change from pure white to a dull, dark yellow. This type of yellowing is patchy and feels damp to the touch. It indicates improper storage, which does reduce absorption speed and dryness – this is a genuine quality issue. When we ship, we reinforce the packaging with moisture proof stretch wrap and add desiccants inside the container, specifically to protect against weeks of high humidity at sea.
Intentionally off white – natural colour of unbleached materials
Sanitary napkins with a 100% cotton top sheet are not stark white. Unbleached cotton fibres have a natural cream or pale yellow colour. Some high end organic cotton products deliberately present this “natural” colour as a selling point. This yellowing is uniform, gentle, and free of spots or dampness.
How to tell if it is a quality problem?
Compare the yellowed sanitary pad against these guidelines:
Uniform pale yellow, located in the core area → normal hot melt adhesive aging, does not affect performance.
Pin head sized yellow spots, individually wrapped and unopened → mild SAP oxidation (uncommon). You can choose a more oxidation stable SAP supplier.
Large, damp, dark yellow patches, feels wet → moisture damage – a quality issue. Check packaging and storage conditions.
Uniform gentle yellow on a cotton topsheet → natural colour of the material, a product feature, not a defect.