UV Exposure

Question:

We are designing steel structures for our gas cylinder storage area outside. We would like to powder coat the finished structure, but since we are located in Arizona, they will be subjected to high ultraviolet ray exposure. Are there any specifications as to what type of powder we should use to reduce fading over time? J. F.

Answer:

Generally speaking, TGIC polyesters and acrylics are the two generic types of powder coatings that are most resistant to UV exposure. Following are more details on how you should select the powder coating.

TGIC polyesters have excellent UV resistance. Because of their excellent mechanical properties, they are the choice of the outdoor furniture and lawn care equipment markets. Acrylics have superior UV resistance to TGIC polyesters, but are more brittle by nature, meaning they do not have the same robust mechanical properties. Mechanical properties will affect how well the coating withstands the rigors of everyday use with the product. Flexibility, impact and hardness are mechanical properties that can be important to a product that will be bumped, bent, hit, dropped or scuffed in every day use.

Choosing the right powder for you means selecting a powder formulation that has all the properties that are appropriate for your application. If you are most interested in UV resistance, then you should chose an acrylic powder coating. If you want good UV resistance and good mechanical properties, choose a TGIC polyester powder coating.

Following are some guidelines for selecting a TGIC polyester powder coating:

Flexibility 180 deg in a 1/8 inch mandrel Impact Resistance 160 inch/lb Hardness 2H Color Light colors are most resistant to fading Pretreatment Iron Phosphate for steel parts and chrome and nonchrome conversion coating for aluminum parts