When it comes to any product “Shelf Life”, “Best before”, “Expiry Date”, “Use before” are common terms that define or suggest a period within which the product has to be used or consumed. Diapers do not generally have an expiration date but what is generally depicted is an indication of the deterioration of efficacy with which it would serve the purpose.
Foxing:-Diapers mostly contain wood pulp and just like paper is made of wood pulp foxing would start when the diaper becomes too old. Well that is just because it is exposed to sunlight and air. That doesn’t mean foxing doesn’t happen in un-opened diapers the diapers could have been manufactured using old pulp and then packed. The absorption rate of liquid by the diapers would diminish as it ages.
Absorption rate:- The absorbed liquid has to be retained by the absorbent and that could also weaken. The retained liquid must not ooze out on any amount of movement or pressure by the baby and as the unused diaper ages this feature of the diaper could reduce in efficacy.
Adhesiveness and Elasticity:- The elasticity around the waist for pant style diapers would reduce and the adhesiveness of the tape for tape styled diapers would diminish as the diapers age. The elasticity of the pant styled diaper would not be gone alltogether when compared to the adhesiveness of the tape or tab style diaper. The wetness indicators would lose its true representation of the wetness assessment as the diaper ages. All said the general best before date for cute seal is 3 years from the date of manufacturing. The above said issues happen only when the diapers are too old and it is better to keep a tab on the quality of the diapers used as to whether it leaks or is just not performing what it is supposed to.