Powder coating can be applied with more versatility than liquid paint, making it attractive for a range of industries. Powder coating thickness can be adjusted as necessary and provide more protection to object.
Powder coating thickness is measured by the micron, or micrometre. Since many powder coatings will be expressed in tens of microns, you can get an impression of how finely they’re applied.
It’s also common to see powder coating measured by the mil, which is a thousandth of an inch—not to be confused with millimetre, as one millimetre equals 1,000 microns and the difference is hundreds of times larger than that between microns and mils.
The standard range of powder coating thickness falls around 40 – 80 microns, though specific recommended ranges will differ depending on the powder supplier and the context in which the coating is being applied. For example:
Powder coating thickness can and should be altered depending on the environment in which it will be used, but there is such as think as too much thickness.
Overdoing the thickness of a coating results in something called orange peel, named for the appearance and texture of its namesake. Too much powder can also result in ‘sagging’ when heated as the powder reaches its glass transition temperature.
The powder coating thickness to coverage ratio is an important aspect of getting the right thickness, as well as abiding by the recommendations of the manufacturer.
Generally, a lower thickness will provide a greater square metre coverage per kilo of powder. However, you must always consider what your end application is.
You must also consider the type of powder coating you’re using.
A single coat of powder should only be so thick for reasons discussed above, however the final thickness of powder coating can be higher due to more than one layer being used. Additionally, a primer might be used for more protection.
Once everything has been applied and cured, it could be that the full thickness of the powder coating—taking into account primer and topcoat—sits around 150 microns or higher.
Thicker does not necessarily mean better, so applying the thickest coat possible isn’t something that should be aimed for. Instead, the substrate and its environment should be considered alongside the powder supplier’s guidelines to find the best and most sensible thickness.
Broadly speaking, the types of powder coating include:
All types offer excellent impact resistance and flexibility at different micron thicknesses.
Polyester powder coatings have good weatherability, whereas epoxy coatings offer superior chemical resistance.
Thickness ranges for these coatings according to the British Coatings Federation (BCF) are:
All powder coatings should come supplied with a technical data sheet (TDS) which outlines the best thickness range according to the manufacturer.
This advice needs to be applied realistically to the specific job at hand and considered with factors like the surface of the substrate and how the coated object is being used post-coating.
To verify powder coating thickness once the job is complete, it can be measured. However, this is best done once cured, so an incorrect coating would likely need to be stripped and redone.
Post-curing measurement methods include using a dry thickness instrument, such as a magnetic gauge, ultrasonic device, or a micrometer.
To measure dry powder thickness before curing, use a powder comb or a magnetic gauge with a special powder probe.
Tomburn provides a diverse range of powder coating products across the UK and internationally. We specialise in powder coatings for various substrates including aluminium, galvanised steel, and mild steel.
Our cost-effective powder coating services last a long time and guarantee the best peace of mind for added protection and durability of your machinery, architecture, and more.
To find out more about powder coating with Tomburn, contact us today.