The Quality Manual is a book that describes all the individual requirements that a product must comply with, in order to be acceptable as a first quality diaper. Due to process control variations, no two diapers are identical. Even when they look the same to the naked eye, there is always at least some small variation. The Quality Manual identifies each diaper component and defines an acceptable tolerance. It also specifies and defines properties of raw materials used to produce each diaper.
There are many individual parameters that need to be defined in a quality manual, such as tape position, leg cuff height, material centerline, diaper folding, pad formation, diaper density, super absorbent distribution, hot melts, frontal tape design, bag diaper count, etc. Many of these parameters can be saved in a program and then fed to an automatic vision system system for automatic inspection. There are other parameters that cannot be viewed with a camera; human interaction is required to detect deviations. Typically, there will be a specification for each kind of diaper made at the factory. In case of private label diapers, it is common for the client to sign the Quality Manual for his diaper brand so he is aware of quality expectations and the factory agrees to a given tolerance.
A good quality factory will look for ways to reduce the tolerances in order to make diapers with tighter specs. A diaper that does not comply with all the requirements is called a “second”. Sometimes these can be sold in the local market, if they do not affect the diaper brand. It is also possible to reclaim the diaper to recover some of the materials and then reprocess them again in the machine. Typically, most diaper manufacturers try to sell their seconds because they can get prices that are higher than what they can recover from the diaper itself but they generally try to sell them outside their local market or export them to other locations to avoid any conflict in the market.