Glossary - F
Fatigue	is a condition of stress from repeated flexing or impact force upon the adhesive-substrate interface; weakening of material caused by repeated loading or and unloading..
Filler	is a relatively non-adhesive substance added to an adhesive to improve its working properties, permanence, strenght, UV-stability or other qualities.
Final strength	The strength of a bonded joint when the adhesive has attained full cure.
Fixation	means holding the bonded assembly in the required position with or without pressure until the adhesive has cured or aquired enough strength to hold the two bonded parts sufficiently in position
Flash-off time	Period necessary for evaporation of the solvents present in cleaners and/or primers used on the surface which is to be bonded.
FMVSS	Abbreviation for Federal Motor Vehicle Safety Standard: American standard, which defines, for example, crashtests on motorvehicles with bonded windshields. Often used is the FMVSS 208 II. Here two adult dummies are secured not only by airbag but additionally by safety belts. The more strong FMVSS 208 I defines a crashtest with two full-size-airbags and two adult dummies without safety belts. In this case, the stress on the bonding of the windshield is several times higher. All Sika®adhesives for the bonding of windshields are tested following the requirements of the most strictly standard FMVSS 208 I .
Fracture energy	The energy that is required to cause a material to fail or to fracture.