# Powder coating

Selecting and qualifying powder-coating systems by chemistry, substrate preparation, deposition, part-temperature cure and inspection.

Reviewed: 2026-11-01

Tags: processes, finishing, powder-coating, organic-coatings

[Compare surface-finishing options](../surface-finishing.md) before specifying the complete route.

**Interpon 200, ANZ Issue 03, November 2025**, specifies **15 minutes at 200°C object temperature**. If a representative part takes **12 minutes** to reach that temperature, the worked example gives **27 minutes** total. Verify part-temperature history across the load and measure cured film at the specified surfaces. [Interpon 200 data sheet, pages 1–2](https://powdercoatings.brand.akzonobel.com/m/53ff46f410b970c0/original/ANZ-TDS-Interpon-200.pdf)


Specify substrate, preparation, powder, deposition and cure. AMPP distinguishes electrostatic spray from processes such as fluidized-bed dipping on preheated parts. Qualify adhesion, corrosion resistance and service exposure separately from color and gloss. [AMPP, powder-coating systems](https://www.ampp.org/technical-research/what-is-corrosion/protective-coatings-learning-center/types-of-powder-coatings-systems)

## Chemistry and process families

Thermosetting powders develop a crosslinked film during cure; thermoplastic powders melt and flow without that thermosetting reaction and can soften again on reheating. These distinctions matter when specifying a process, but they do not establish a universal service temperature. TCI separates melting and flow from the later development of thermoset properties: a smooth-looking film can precede sufficient cure. [TCI, *Guide to the Application & Troubleshooting of Electrostatic Coatings*, chapter 11; linked copy has no verified printed issue date](https://tcipowder.com/media/2480/troubleshooting-guide-rebranded-2019.pdf)

Interpon's technology portfolio lists epoxy, hybrid, polyester, polyurethane, acrylic, fluoropolymer and silicone chemistries, as well as UV-cured technologies. Resin-family names are therefore useful screening information, not interchangeable product specifications. [Interpon technology portfolio](https://www.interpon.com/ae/en/technologies)

| Selection question | Information to obtain |
| --- | --- |
| Interior, exterior or sheltered exposure? | Named grade's weathering evidence, colour/gloss retention and complete coating system |
| Chemical splash, immersion or cleaning? | Actual fluid, concentration, temperature, duration and applicable supplier data |
| Heat-sensitive or previously heat-treated part? | Permitted part thermal history and a compatible coating/cure route |
| Flexible component or post-coating forming? | Qualified bend/impact behavior for the selected finish and substrate |
| Functional film rather than appearance only? | Relevant electrical, wear, release or corrosion requirements and test conditions |

For a bounded contrast, the **Interpon 100 Issue 007, August 2012** sheet describes an epoxy intended where prolonged UV or exterior exposure is not anticipated, and notes chalking and gloss loss outdoors. That historical product sheet illustrates a limitation; it is not a current purchase approval or a rule that every epoxy system has identical durability. [Interpon 100 data sheet](https://www.specifyinterpon.com.au/wp-content/uploads/Interpon-100-TDS.pdf)

## Substrate preparation and complete systems

Cleaning and pretreatment must address the actual alloy and its condition. Thermaset identifies different possible preparation routes for ferrous metal, aluminium, galvanised steel and stainless steel; primer selection also depends on the substrate, exposure and intended performance. Its guidance treats the complete coating system as the unit to specify and test. A bare statement such as “blast and powder coat” leaves those decisions unresolved. [Thermaset powder-coating FAQs, sections 20–21](https://thermaset.co.uk/powder-coating-powder-faqs/)

Provide the applicator with information about oils, oxide, previous coatings, welds, castings and inaccessible cavities. Decide which preparation and coating operations apply inside cavities as well as on visible faces. Where outgassing is a concern, develop an appropriate pretreatment/preheat or powder strategy rather than assuming a thicker film will close defects. TCI discusses preheating porous cast iron or aluminium as one way to reduce gas-related blistering; suitability remains dependent on the component and process. [TCI guide, chapter 11](https://tcipowder.com/media/2480/troubleshooting-guide-rebranded-2019.pdf)

## Deposition, recesses and masking

Electrostatic deposition depends on equipment, part presentation and grounding. Nordson's **EXP-100M manual 33-16, part 106 715B, issued April 2000**, explains the Faraday-cage difficulty as attraction of powder toward projecting areas surrounding a recess. It describes trade-offs between voltage, powder delivery, recess penetration and wraparound. This historical equipment example supports the mechanism, not a transferable gun-voltage or air-pressure recipe. Use the instructions for the installed equipment and trials on representative geometry. [Nordson manual, sections 4-2 to 4-4](https://emanuals.nordson.com/finishing/files/Powder/106715B.pdf)

Inspect recesses, returns, edges and hidden surfaces deliberately. An acceptable broad face does not establish adequate coverage in a channel or deep hole. State permitted rack/contact locations and coordinate them with electrical continuity through the coating operation.

Mask functional no-coat areas before production. EPSI identifies threads, ports, sealing lands, bearing surfaces and grounding/contact areas as common masking needs, using caps, plugs, tapes or discs selected to the geometry. Define the boundary and permissible coating encroachment on the drawing; include the thermal cycle when qualifying the masking material. [EPSI powder-coating masking guidance](https://www.epsi.com/powder-coating-process)

## Part temperature, cure and a bounded product example

**Interpon 200, ANZ Issue 03, November 2025**, is a polyurethane powder with a stated schedule of **15 minutes at 200°C object temperature**. Its mechanical, chemical and durability results were obtained on **chromate-conversion-coated aluminium**, with **60–80 µm gloss film** and that cure. Reduced-gloss finishes may have lower mechanical results. Its salt-spray entry reports **1,000 hours**, with no corrosion area more than **2 mm from the scribe** under the cited AS3715 method. Preserve these specimen and method conditions; the result is not a 1,000-hour guarantee for every fabricated assembly or a conversion to outdoor service years. [Interpon 200 data sheet, pages 1–2](https://powdercoatings.brand.akzonobel.com/m/53ff46f410b970c0/original/ANZ-TDS-Interpon-200.pdf)

**Original timing example:** assume a representative part reaches 200°C only after **12 minutes** in an oven. If it then remains at the required object temperature for the product's **15-minute** dwell, the simplified total is **27 minutes**. Removing it after 15 minutes total would provide only **3 minutes** at that temperature. The assumed heat-up time is illustrative; neither 27 minutes nor an oven-air setpoint is a production recipe. Measure the relevant part-temperature history and validate the supplier's cure window across the load.

## Thickness and inspection scope

State dry-film minimum and maximum, significant surfaces and measurement locations. **ISO 2808:2019**, edition 5, July 2019, confirmed in 2026, covers methods for wet film, dry film and uncured powder-layer thickness, with method applicability and precision information. These are different measurements; a pre-cure powder reading should not be silently reported as final dry-film thickness. Select a method suited to substrate, geometry and roughness. [ISO 2808](https://www.iso.org/standard/71583.html)

Choose each performance test for its intended question. **ISO 2409:2020**, edition 5, August 2020, assesses resistance to separation after cross-cutting; it does not measure adhesion strength. Its scope excludes textured coatings and total thickness above **250 µm**. A revision project does not replace the published edition. Specify the applicable method, conditioning and acceptance class rather than requiring an unsuitable test for a heavy textured film. [ISO 2409](https://www.iso.org/standard/76041.html)

Release records should connect powder identity/batch, substrate preparation, cure history, thickness and appearance to the inspected parts. Qualify corrosion, flexibility, cleaning and any post-coating bonding or forming separately where required. Follow the selected powder's current SDS and installed equipment instructions for handling, extraction, grounding and curing; a dry application process still requires controlled industrial handling.

## Related reference

[Surface-finishing processes](index.md)