In two words, explain this phenomenon "the diversity of construction materials, the instability of sealants".

First of all, the diversity of construction materials: there are many types of construction materials on the market, such as aluminum, there are spray aluminum and anodized aluminum. The sprayed aluminum is divided into various coatings such as electrophoresis and fluorocarbon. The surface properties are different, so it is necessary to know the strength of the adhesion through experiments. Plasticizers and fillers, but now there are many manufacturers and the materials used are different, so there is also great uncertainty.

More on the instability of the sealant: As a chemical product, many factors affecting quality cannot be directly observed, so we recommend that you do a compatibility test before construction.