Polyester vs Epoxy Powder Coating: Which Should You Choose?
Choosing the right powder coating involves much more than selecting a colour and finish. The environment in which the finished component will be used, the required durability, exposure to weather and chemicals, and the substrate itself can all influence which type of powder coating is most appropriate.
Polyester and epoxy are two established powder coating technologies, but they offer different characteristics and are suited to different applications.
So, what is the difference between polyester and epoxy powder coating, and how do you decide which one to use?
What Is Polyester Powder Coating?
Polyester powder coatings are widely used for both interior and exterior applications.
Thermaset’s polyester powder coatings are formulated using selected polyester resins and pigments to provide a tough decorative finish with excellent outdoor durability and resistance to yellowing.
This makes polyester particularly useful where coated components will be exposed to outdoor conditions.
Thermaset polyester powder coatings are available in:
- Gloss
- Semi-gloss
- Matt
- A wide range of colours
- RAL and BS colour matching
- Bespoke colours matched to customer-supplied samples
The range also provides good mechanical properties, including flexibility, impact resistance, adhesion and scratch resistance.
Where Is Polyester Powder Coating Used?
Because of its combination of decorative appearance and outdoor durability, polyester powder coating can be used across a wide variety of commercial and industrial applications.
The key consideration is often whether the finished component needs to withstand prolonged exterior exposure.
Thermaset’s polyester powders are specifically designed for both interior and exterior use and provide excellent outside durability.
They also offer generally good resistance to acids, alkalis and oils at normal temperatures.
What Is Epoxy Powder Coating?
Epoxy powder coating has different characteristics.
Thermaset’s epoxy powder coatings are formulated to produce hard, durable protective finishes with excellent adhesion and chemical resistance.
They are particularly suited to applications where protection from aggressive environments is required and long-term exposure to weathering or ultraviolet light is not expected.
Recommended uses include general industrial components and applications requiring a good all-round protective coating.
Thermaset also identifies automotive components and household goods among applications for its epoxy powder coatings.
Is Epoxy Powder Coating Suitable for Outdoor Use?
This is one of the important differences between epoxy and polyester powder coatings.
Thermaset’s epoxy powder coatings are not designed for long-term exterior exposure. The company’s technical information states that some chalking and loss of gloss can be expected following continuous outdoor exposure.
Where long-term exterior durability is required, a suitable polyester powder coating should therefore be considered instead.
This makes understanding the final location and use of the component particularly important when specifying the coating.
What Is Epoxy Polyester Powder Coating?
There is also another important Thermaset range: epoxy polyester powder coating.
Thermaset’s epoxy polyester powders combine selected epoxy and polyester resins to produce a tough decorative finish with excellent mechanical properties, chemical resistance and superior heat stability.
They are designed mainly for interior applications.
Typical applications identified by Thermaset include:
- Domestic appliances
- Office furniture
- Shop fittings
Where ultimate outside durability is required, Thermaset recommends selecting a suitable polyester powder instead.
Polyester vs Epoxy Powder Coating
The right choice depends on what the coating needs to achieve.
Outdoor Durability
Polyester powder coating is designed for interior and exterior applications and offers excellent outdoor durability.
Epoxy powder coating is not designed for prolonged exterior exposure.
Chemical Resistance
Thermaset’s epoxy coatings offer excellent chemical resistance and are particularly suited to applications requiring protection from aggressive environments.
Thermaset polyester powders also provide generally good resistance to acids, alkalis and oils at normal temperatures.
Adhesion
Epoxy powder coatings provide excellent adhesion when applied to an appropriately prepared substrate.
Correct cleaning and pre-treatment remain important for achieving the required coating performance.
Decorative Appearance
Both polyester and epoxy technologies are capable of producing attractive decorative finishes.
Thermaset offers its polyester and epoxy powder coating ranges in gloss, semi-gloss and matt finishes, with a wide selection of colours available.
What About Colour?
The required coating technology does not mean you have to compromise on colour.
Thermaset polyester powders can be matched to customer-supplied samples or many RAL and BS colours.
Its epoxy powder coatings are also available across a wide range of RAL and BS colours and can be matched to specific customer requirements, with smooth and textured finishes available.
Thermaset’s epoxy polyester range offers even broader matching possibilities, including many RAL, BS, NCS and Pantone colours.
This allows the technical requirements of the coating to be considered alongside the required appearance.
Surface Preparation Is Important
Whichever powder coating technology is selected, correct substrate preparation is essential.
Thermaset recommends that substrates are thoroughly cleaned of grease, rust and other contamination before coating.
Depending on the substrate and required level of protection, appropriate pre-treatment may also be required.
This can include specific preparation processes for aluminium, galvanised steel and ferrous substrates.
Which Powder Coating Should You Choose?
Rather than choosing solely by colour or price, consider the environment in which the finished component will operate.
Questions to consider include:
- Is the component for interior or exterior use?
- Will it experience prolonged exposure to sunlight and weather?
- Does it require particular chemical resistance?
- What substrate is being coated?
- What colour is required?
- Is a matt, semi-gloss or gloss finish required?
- Are there any particular performance requirements?
For applications requiring excellent outdoor durability, polyester powder coating will often provide the appropriate solution.
For interior applications where a hard, durable protective coating with excellent adhesion and chemical resistance is required, epoxy powder coating may be more suitable.
For interior products requiring a tough decorative finish with excellent mechanical properties and heat stability, epoxy polyester powder coating provides another option.
Powder Coatings from Thermaset
Thermaset manufactures an extensive range of powder coatings for commercial and industrial applications, including polyester, epoxy and epoxy polyester systems.
A wide selection of colours and finishes is available, with many powder coating products available to order through the Thermaset online shop.
If you’re unsure which type of powder coating is suitable for your application, the Thermaset team can also provide technical guidance to help you select the appropriate product.
Explore the Thermaset powder coating range or contact our team to discuss your requirements.
