A sealant or an adhesive holds no better than the surface it is applied to. Check these points before every application.
A clean surface
Remove dust, grease, oil and any remains of old joints or glue. A greasy, dusty or dirty substrate compromises adhesion.
A dry surface
Never apply to a damp substrate. After cleaning with water, let it dry completely.
The right places
Silicones are not for use below ground level, in confined spaces or on surfaces that will be painted later. Do not apply silicone to a substrate hotter than 50 °C.
Well-stored cartridges
Store cartridges in a cool, dry place, and check the current technical data sheet before any technical use.