A polymer spray coating is a material-and-process combination. Begin with the substrate and the service exposure, then select a deposition route and prove the finished coating on representative parts. A useful purchasing brief specifies what the coating must withstand and how the supplier will demonstrate it.
Distinguish the application routes
Thermoplastic powders form a coating by melting and cooling. Thermoset powders require their specified chemical cure. Liquid coatings have their own drying or cure chemistry. These differences determine the thermal exposure, preparation and inspection questions to ask.
Axalta's thermoplastic coating methods describe electrostatic powder spraying followed by oven heating, uncharged powder sprayed onto a preheated metal surface, and flame spraying in which powder melts during application. Its examples concern compatible products and metal substrates. A portable applicator still needs an application-specific process plan.
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| Route | Question to resolve | Evidence to request |
|---|---|---|
| Electrostatic powder spray | Can the part be grounded and heated by the specified route? | Coverage of recesses and edges, part-temperature record and finished-film results |
| Hot-substrate powder spray | Will the geometry retain enough heat for consistent fusion? | Temperature variation across thick and thin sections and coating continuity |
| Flame-applied thermoplastic | Is the exact material/substrate system supported for this repair or coating? | Manufacturer procedure, site controls and representative trial results |
Describe the substrate and service
Give the supplier a drawing, substrate grade, wall thickness, existing finish and areas that must remain uncoated. Include joints, sharp edges, recesses and any heat-sensitive inserts. State temperature cycles, liquid exposure, abrasion, cleaning agents and the appearance requirement. Compatibility with one metal panel establishes little about a bonded assembly or a different substrate.
Ask for the coating grade, primer requirements, preparation method, process limits and inspection plan in writing. Use the current technical and safety data sheets and the actual equipment manual to establish handling, ventilation, ignition and thermal controls with the responsible site specialists. Process temperatures belong to that qualified system, not a generic polymer name.
Make the trial explain the result
Use coupons made from the actual substrate alongside a representative part. Record preparation, roughness where specified, coating batch and application history. Include difficult locations in the thickness map. Select the gauge and probe for the coating/substrate combination; Elcometer's probe-selection guidance shows why a method suitable for one combination may need changing for another.
Agree on an adhesion test suitable for the coating thickness and substrate. Record the method, conditioning and where separation occurs. A numerical result without its failure location can hide whether the coating, interface or test adhesive failed. Add exposure tests that represent the stated service, with agreed duration and observations.
Fictional thickness example: a trial requires every specified point to be 350–450 micrometres. Readings of 370, 410 and 460 have a mean of 413.3, but the last point exceeds the maximum. Preserve all readings and investigate local deposition before repeating the trial. These are invented criteria, not universal coating limits.
Release the complete coating system
Compare repeated runs, repaired areas and representative geometry against the same requirements. Keep photographs, individual measurements and exposure observations with the process revision. A substrate, primer or application change should trigger review of the affected evidence. For more detail on preparation and inspection records, see the industrial primer guide.
Use the working record
Download the editable polymer coating trial. Save a copy, complete the actual requirements and evidence fields, and review open issues with the responsible owner. The plain-text record includes instructions, units where needed, the fictional example, and source references.