What's in a powder coating?
So what's in a powder coating?
There are six main ingredients that make up the recipe for powder coatings.
- Resin is always present and comes in two types; polyester and epoxy.
- Curing agents are added to bind the coating. For polyesters, primid curing agents are used. For epoxies, dicyandiamide curing agents are used. Hybrid curing agents are also occasionally used, which contain different quantities of the primid and dicyandiamide curing agents.
- There are various additives that are often used with a wide range of properties. Some of these give the powder a matt effect and others create a hardened finish, for example.
- Post additives prevent the powder from caking and are added when the powder is hard and broken into small chips.
- Tint pigments are also added to the mix. There are two types; inorganic, which are generally pale and dull and organic, which are more brightly coloured.
- Extenders (fillers) are added to reduce glossiness and supply the coating with extra durability.
The quantity of each ingredient differs depending on a number of factors.
The powder may be thermoplastic (becomes soft, remoldable and weldable when heat is added) or thermoset polymer (can not be welded or remolded when heated).