The full mechanical and chemical-resistance properties of a powder coating develop in the last stages in the curing cycle. Most issues regarding mechanical problems will be corrected by addressing the cure conditions.
Adhesion can be tested using a sharp blade to create perpendicular cross cuts 1mm and 2mm apart. Very poor adhesion will be apparent as total delamination of the squares; but finer degrees of adhesion can also be discerned with reference to ISO 2409 and rated 0-5 (best to worst).
Corrosion occurs under the correct environmental conditions, and usually involves the metal substrate, salts and moisture in the presence of oxygen. Corrosion will cause the delamination of the coating, usually first apparent as blistering of the coating or filiform corrosion.
Not every coating will have the same flexibility or toughness. Sometimes these attributes are not important in the final requirement of the coating, however on occasion these properties are vital, for example in a post-forming context. Mechanical tests are often carried out as part of QC process as an indicator of cure and include many testing procedures, from falling weight impact, to pencil hardness, to scratch or abrasion testing.
Every powder coating system, polyester, epoxy, acrylic, etc, will have its own intrinsic resistance to chemical attack. A coating's resistance to chemicals can be tested in a number of ways, most usually by prolonged exposure, either a spot test or by partial submersion in the liquid chemical.