Uneven curing is another situation. It'd be due to wrong mixing or temperature complications. Make sure to mix effectively and preserve the temperature steady. Polyester epoxies are used as powder coatings for washers, driers and also other "white products". Fusion Bonded Epoxy Powder Coatings (FBE) are extensively used for corrosion https://www.propanraya.com/id/produk/epoxy-fast-dry