# Epoxy powder coatings

Epoxy powder families, part-temperature cure, preparation, film control and limits of corrosion and chemical-resistance claims.

Reviewed: 2026-11-01

Tags: consumables, coatings, epoxy, powder-coating

AkzoNobel's **Interpon 100** lab tests use **5 minutes at 200°C object temperature** on **zinc-phosphated polished steel** at **60–70 µm film**. Its recommended application thickness is **60–90 µm**. Treat the test bake as part of the reported specimen construction and qualify the actual preparation and bake separately. [Interpon 100 TDS, V12, 26 May 2024](https://powdercoatings.brand.akzonobel.com/asset/f56d0902-f933-4fba-a6a5-1e23da0440e9/EMEA-TDS-Interpon-100.pdf)

Select the epoxy powder with its substrate preparation, application route, film thickness and cure. Qualify corrosion, chemical compatibility and weathering for the complete system.

## Identify the coating family

**Decorative/protective epoxy powders** include Interpon 100 for interior components over properly prepared metal. [Interpon 100 TDS, V12, 26 May 2024](https://powdercoatings.brand.akzonobel.com/asset/f56d0902-f933-4fba-a6a5-1e23da0440e9/EMEA-TDS-Interpon-100.pdf)

**Fusion-bonded epoxy (FBE)** includes functional pipe-coating formulations applied to heated substrates. Products may serve as a standalone barrier or as a layer in a larger system. For example, 3M Scotchkote 226N is a one-part, heat-curable thermosetting epoxy powder for pipe corrosion protection. Its available cure speeds are formulation choices, not interchangeable settings for any FBE. [3M 226N TDS, copyright 2012](https://multimedia.3m.com/mws/media/638373O/3m-tm-scotchkote-tm-fusion-bonded-epoxy-coating-226n.pdf)

**Epoxy–polyester hybrids** are another family. Interpon describes them as blends mainly used indoors, with improved UV, color and heat performance relative to pure epoxy, but limited UV resistance. A hybrid designation therefore does not establish suitability for an exposed exterior. Specify the resin family and exact product code rather than ordering only “powder coat.” [Interpon hybrid technology](https://www.interpon.com/ch/en/technologies/hybrid)

## Preparation and application belong in the specification

Remove contamination before coating; powder does not replace cleaning or a corrosion pretreatment. Sherwin-Williams' FBE Epoxy TB-BT Grey RAL 7016 sheet requires surfaces free of oil, grease and flash rust, and describes steel blasting and/or iron or zinc phosphating. Its application options include electrostatic spray, tribo equipment and a fluidized bed on a preheated support. These options are specific to that formulation and application procedure. [Sherwin-Williams product data, revised 27 January 2022](https://www.paintdocs.com/docs/webPDF.jsp?SITEID=BOLTON_EX&doctype=PDS&lang=en_GB&prodno=20750E)

A useful purchase or process specification names the substrate and its condition, cleaning and pretreatment route, areas to mask, required film range, cure window and inspection criteria. Confirm compatibility with galvanized steel, aluminum or an existing coating rather than transferring a steel-panel result. Include edges, recesses and complex geometry in production trials: a flat test panel does not establish coverage of the actual component.

## Cure follows the part temperature

An oven setpoint is not a measurement of the coated part. A schedule expressed as a time at part-metal temperature starts its holding period when the part reaches that temperature. Prismatic Powders specifically identifies checking part-metal temperature as necessary to determine when the cure timer starts. Record a representative part temperature profile when qualifying a load; component mass and loading arrangement must be represented. [Prismatic Powders, checking part-metal temperature, effective 16 November 2020](https://www.prismaticpowders.com/knowledge-base/170/checking-part-metal-temperature)

For a bounded example, the Sherwin-Williams product above specifies preheating the substrate to 180 °C and holding **14 minutes after the part metal reaches 180 °C**, with a recommended 130–330 µm film. Its gel time is only 30–35 seconds at 180 °C. Gelation is thus not evidence that the specified cure is complete. Do not substitute that schedule for a decorative epoxy or another FBE. [Sherwin-Williams product data, revised 27 January 2022](https://www.paintdocs.com/docs/webPDF.jsp?SITEID=BOLTON_EX&doctype=PDS&lang=en_GB&prodno=20750E)

Control both under-cure and excessive thermal exposure. PPG describes oven monitoring as a means of detecting temperature variation and maintaining cure consistency. For multilayer work, assess the thermal history of each layer with its supplier rather than assuming that another oven pass is harmless. [PPG powder-coating FAQ](https://www.ppg.com/en-US/industrialcoatings/frequently-asked-questions)

## Read performance together with the test construction

Interpon 100 illustrates why the test conditions matter. The following are typical laboratory results on **zinc-phosphated, polished steel**, coated at **60–70 µm** and cured **5 minutes at 200 °C object temperature**:

| Test | Reported result |
| --- | --- |
| ISO 2409 cross-cut adhesion, 2 mm spacing | Class 0 |
| ISO 6272-2 impact | 2.5 J, direct and reverse |
| ISO 9227 salt spray | 500 hours; corrosion creep no greater than 3 mm from the scribe |
| ISO 6270-2 CH humidity | 1,000 hours; no blistering or gloss loss |

Compare salt-spray evidence using the test’s pretreatment, film and damage conditions. Use separate evidence for field durability. [Interpon 100 TDS, V12, 26 May 2024](https://powdercoatings.brand.akzonobel.com/asset/f56d0902-f933-4fba-a6a5-1e23da0440e9/EMEA-TDS-Interpon-100.pdf)

FBE results need equally careful boundaries. Jotun Jotapipe AC 1003 is designed as a primer in multilayer polyolefin systems. The TDS lists application at 205–240 °C and 150–500 µm depending on the process. Its three variants have different gel and cure times: at 232 °C, maximum cure times are 60, 110 and 150 seconds for 21S, 35S and 50S respectively. These are not alternative oven recipes for an unspecified powder. [Jotapipe AC 1003 TDS, 25 May 2022](https://www.jotun.com/Datasheets/Download?url=%2FTDS%2FTDS__16421__Jotapipe+AC+1003__Euk__GB.pdf)

The same Jotun sheet's typical performance specimens are **300–400 µm standalone FBE on 6 mm steel plates without chemical pretreatment**. Do not confuse those specimen conditions with a complete multilayer pipeline specification. Its stated continuous pipeline temperature up to 98 °C is conditional on application, pipe configuration, the coating system and local field conditions. [Jotapipe AC 1003 TDS, 25 May 2022](https://www.jotun.com/Datasheets/Download?url=%2FTDS%2FTDS__16421__Jotapipe+AC+1003__Euk__GB.pdf)

## Exposure limits and production control

Chalking is degradation of a cured coating, not loose application powder. Dulux explains that UV breakdown of the binder loosens pigment at the surface, and that epoxy resin coatings exposed outdoors without a suitable topcoat can yellow and chalk. Specify a manufacturer-approved exterior system where appearance and weathering matter; chemical or corrosion resistance does not establish UV durability. [Dulux technical advice: chalking](https://www.duluxtrade.com.au/technical-advice/performance/chalking/)

Treat chemical compatibility as an exposure-specific question: identify the fluid, concentration, temperature, contact duration, immersion or splash duty, and cleaning cycle. For pipelines, also establish mechanical damage and cathodic-protection conditions. 3M cautions that 226N field performance depends on the complete system and local conditions, and cannot be predicted solely from laboratory results. A temperature rating or family-level resistance claim is insufficient for a new service. [3M 226N TDS, copyright 2012](https://multimedia.3m.com/mws/media/638373O/3m-tm-scotchkote-tm-fusion-bonded-epoxy-coating-226n.pdf)

Keep powder identity and reclaim practices controlled. Interpon 700 EJ412JR, an epoxy–polyester example, recommends a single batch for a visible assembly, prohibits mixing different product codes, and requires consistent reclaim practice with at least 70% virgin powder under its stated guidance. Its storage limit is 24 months at no more than 30 °C; neither that lifetime nor reclaim ratio applies automatically to another product. [Interpon 700 EJ412JR TDS, version 1, 14 October 2024](https://powdercoatings.brand.akzonobel.com/m/7e63795a4219627e/original/EMEA-TDS-Interpon-700-EJ412JR.pdf)

For qualification, retain the exact product and batch, pretreatment, measured film range, part temperature history and application conditions alongside adhesion and exposure results. Resolve failures against that actual construction before changing powder chemistry. See [Surface-finishing processes](../../processes/finishing/index.md) for the wider process context.