We get the question every week: why powder coat instead of using liquid paint? The short answer comes down to three points: a thicker film, no solvent and less waste. The full answer also includes a few limits, and we prefer to name them.
A coating made of 100% solids
A liquid paint contains resin, pigments and a solvent or another liquid carrier, which evaporates as the paint dries. According to the manufacturer TIGER Coatings, the solids content of a liquid paint ranges from less than 30% to more than 60%. A powder, on the other hand, is 100% solids: everything that lands on the part stays on the part.
The result can be measured. According to Powder Coated Tough, the Powder Coating Institute's magazine, one coat of powder gives 2.5 mils or more (about 60 µm), compared with 1 to 1.2 mils (25 to 30 µm) for one coat of liquid paint. So a single coat of powder is often enough where liquid would take several.
Less waste, but not 95% everywhere
Powder that does not reach the part can be reclaimed and reused. The Powder Coating Institute cites a utilization rate of more than 95% with reclaim. That figure holds for a line that applies the same colour continuously. On the first pass, transfer efficiency is lower, from 25% to 60% depending on the shape of the parts, and in a shop that changes colour several times a day, reclaim is hard to justify. The advantage that holds true everywhere: no solvent to evaporate or treat.
Where liquid paint keeps the edge
Powder has to be cured in an oven, generally between 160 and 200 °C. A part that cannot take that heat, or that does not fit in an oven, gets painted with liquid. Liquid paint also remains better for very thin films, perfectly smooth surfaces and certain metallic effects. For very large parts and shapes full of recesses, Products Finishing also considers it preferable, all the more since a two-component liquid paint cures without an oven. And in both cases, performance depends first on the formulation chosen and on the preparation of the metal.
At the shop, we coat metal that goes in the oven: wheels, automotive parts, aluminum extrusions, sheet metal and production parts. Every part is degreased, rinsed and pretreated with zirconium before application. If powder is not right for your part, we will tell you in the quote.
In summary
- A powder is 100% solids: no solvent, and a film of about 60 µm in one coat.
- The 95% utilization rate assumes reclaim, which is hard to justify when you change colour often.
- Liquid paint keeps the edge for heat-sensitive parts, very large parts and very thin films.
- Powder or liquid, the preparation of the metal decides how long the finish lasts.
