For any bonding process, there are always some 8 steps that should be done:
* surface preparation of the materials,
* preparation of the adhesive or binder, for instance mixing if it is a 2 components adhesive,
* application of the adhesive on one or both substrates,
* waiting before assembly,
* assembly of the parts,
* pressing the parts together,
* drying or curing in order to obtain a solid joint,
* waiting consolidation before shipment of bonded parts.
For each of these steps, there are some requirements and the adhesive should display some specific characteristics in order to meet these requirements.
Viscosity has been defined in other chapters. It measures the resistance to flowing of the adhesive. It is measured in mPa.s (milli Pascals. Second), with a viscometer such as Brookfield viscometer (or other types and brands), see figure 1, according to various testing standards, for instance european standard EN12092, American standards ASTM D1084 , D2256 etc…