Powder inspection should cover at least appearance, thickness, cure, adhesion, color/gloss and functional fit. No single metric is sufficient: correct thickness can still delaminate after poor pretreatment, adhesion can pass while under-cure harms chemical resistance, and salt-spray success does not prove outdoor life.
Values in this article support engineering screening during design review, RFQ and prototyping. They do not replace formal calculations, material data sheets, qualified procedures or contractual standards.
EXECUTABLE CONTROL PLAN
1. Pretreatment: record bath concentration, pH, temperature, spray/immersion time, conductivity and water-break behavior against supplier windows. 2. Thickness: magnetic method such as ISO 2178 for steel; eddy-current method such as ISO 2360 for non-ferrous substrates. Define points, shims, local and mean ranges. Common 60–120 μm is only a starting range. 3. Cure: record part metal temperature (PMT) and hold time, not oven-air setting alone; profile the coldest point in mixed heavy/thin loads. 4. Adhesion: ISO 2409:2020 cross-cut classifies resistance to separation; it does not directly measure adhesion strength and is unsuitable above 250 μm or on strongly textured coatings. ASTM D3359-23 is another tape method; do not mix rating systems contractually. 5. Appearance: under approved light/distance inspect particles, pinholes, craters, holidays, orange peel and rack marks; compare color/gloss to a master.
SAMPLING NOTE
Measure all defined zones on the first-off; sample stable production per control plan, while grounding, threads and fits receive 100% mistake-proof/visual confirmation. Use same-lot witness panels for destructive adhesion unless the contract requires a nonfunctional part area.