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Architectural Powder Metallics: What You Need To Know
Understanding Metallics – the difference between powder and liquid
Sparkle, shimmer, pearl, sheen…the trend for coatings with that extra something is still going strong!
And now we can add metallics effects to speckles and physical textures for a more natural and interesting look.
What do you know about Metallic/Mica effect powders? Joey Roush, IFS bonding expert, explains all…
What are metallic effect powders?
Simply put, this is a general term for powders with mica or aluminum flake added to the base coat to achieve a desired effect. These effects include sparkles, shimmer, pearl effects and more.
To make the powder sparkle either mica, aluminum flake, or a combination of both is used. What’s the difference?
There are two main types of effect pigments used to make metallic or ‘sparkle’ type coatings: aluminum and mica. Mica is a type of mineral that is very thin and flaky. This mineral is then coated with various types of pigments to achieve colors ranging from pearlescent whites to rich coppers, bronzes and golds. Most of the mica pigments are transparent, which allows the base color to show through – this has a great influence on the overall color. Aluminum flakes on the other hand are fully opaque. The higher the loading of aluminum; the greater the silver appearance and the less visible the base color.
There are different colors, shapes and sizes of metallic effect pigments and metallic coating experts identify which ones to use depending on the look desired.
Are mica and aluminum also used in liquid paint?
These effect pigments can be added to either liquid or powder coatings, and they look fantastic in both. We use the pigments to create everything from a fine shimmer through to a heavier sparkle in a performance coating.
What are the differences in using metallics in powder vs. liquid?
Let’s put all our cards on the table - there are some limitations to what can be achieved in powder. The most significant difference between liquid and powder lies in the lower viscosity of liquid paint. The lower viscosity allows for a much higher loading of effect pigment to be used while still maintaining favorable application properties. A liquid coating can have up to 25% metallic pigment loading, while most powders can only have around 5-6% loading. The left photo below shows a liquid coating under 20X magnification, while the right is of a similar shade powder. The loading and depth of the liquid is much greater than that which can be achieved in powder.
Another common practice in liquid is to utilize a multi-coat system. Often a solid base coat will be applied and then a highly metallic loaded clear coat will be applied. This achieves a nice metallic appearance with the characteristic flop of the base coat. Most powder applications are single coat systems, where the opacity and metallic appearance are achieved simultaneously.
However, with trends moving away from “super sparkle” effect coatings and towards more elegant, subtle effects, performance powders can deliver beautiful metallic effects plus they come with the advantage of an improved sustainability footprint compared to a liquid coating.
How are metallic powders manufactured?
The first stage is simple – we make the powder base (color) coat. Once we have our base coat there are two options to turn it from a solid color into the metallic effect coating desired.
1. Dry blending
Dry blending is a quick and simple process where a powder coating and an effect pigment are simply mixed together. This process is very cost effective and can be successfully utilized under certain circumstances. Some of the main benefits include smaller minimum order quantities and quick turnaround times. However, a dry blended product is more susceptible to application issues, depending on the color and loading of the effect pigments. Powder particles and effect pigment particles react differently to the corona field during application and can give a splotchy appearance if unbonded. In fact, some colors cannot be achieved in a dry blend. For example, colors with high effect pigment loading will likely experience ‘spitting’ during application, which is a collection of effect pigment on the spray gun electrode that is transferred to the part. The end result is like it sounds - it will appear as a blemish on the coating.
2. Bonding
Bonding is more common and generally recommended for architectural powder applications.
Bonding is a more complex process compared to dry blending. During the bonding process, a powder coating is heated using friction in a mixing vessel, to the point where the outside of the powder becomes sticky. The effect pigment then adheres to the powder particle. A properly bonded powder will yield a much more consistent finish as compared to a dry blend. Another benefit is that the powder can also be successfully reclaimed with minimal color shift. Bonding also allows for colors with higher effect pigment loading to be successfully applied. For the architectural market, where both high levels of performance and aesthetics are required, bonded metallics are the sensible option.
IFS Coatings has an excellent in-house bonding department ensuring excellent quality control and faster lead times.
With liquid paints clear coats are always used with metallic/mica coatings – do I also need to specify a clear coat for powder metallics?
With a liquid coating the clear coat is needed to help protect it from scratch and mar, and meet the AAMA spec performance requirements. The clear coat also helps protect the flakes from degradation - especially at the low film thickness liquids must be applied at.
With powder coatings, that’s not the case. The scratch and mar resistance of powder is much better due to its thermosetting properties, and the effect pigments used to conform to the AAMA performance specifications are encapsulated with a specialized coating that protects them from degradation. This coating, or protection, of the effect pigment ensures architectural grade powders meet and exceed the AAMA performance specifications without the use of a topcoat.
Single coat, same performance, gorgeous aesthetics and an improved environmental footprint. Metallic performance powders deliver an excellent option.