7 Standards To Test Weathering Resistance of Powder Coatings
There are 7 standards to test weathering resistance of powder coatings.
- Resistance to mortar
- Accelerated ageing and UV durability (QUV)
- Humiditytest (tropical climate)
- Chemical Resistance
Resistance to mortar
According to the standard ASTM C207. A specific mortar will be brought in contact with powder coating during 24h at 23°C and 50% relative humidity.
Accelerated ageing and UV durability (QUV)
This test in the QUV-weatherometer consists of 2 cycles. The coated testpanels are 8h exposed to UV-light and 4h to condensation. This is repeated during 1000h. Every 250h the panels are checked. Herewith the coating is tested on colour- and gloss retention.
Salt spray test
According to the standards ISO 9227 or DIN 50021. The powder coated panels (with an andreas cross scratched in the middle through the film) are placed in a warm humid environment and sprayed with salt. This test evaluates the degree of protection from the coating to corrosion in a salty environment (e.g. at the seaside). Usually this testcase takes 1000h, with checks executed every 250h.
According to the standards DIN 50018 or ISO3231. Gives a good indication to the resistance of the coating in a industrial environment. For a specific period a coated test panel is placed in a warm humid environment, which contains sulphur dioxide. This test is running 24h-cycle with controls every 250h.
During minimum 1 year the coated testpanels are exposed to the sunny and humid environment of Florida, USA. Gloss as well as colour retention are evaluated.
Humidity test (tropical climate)
According to the standards DIN 50017 or ISO 6270. Is executed in a chamber with a environment of saturated humidity, at a determined temperature and often during 1000h. Every 250h a control is executed on the powder coated panels and a Andreas-cross scratched with a knife through the film in the middle. This test evaluate the under creep of humid and corrosion in a humid environment.
Chemical resistance Is often tested on coatings that are subjected to maintenance, contact with detergents or chemicals. Standard conditions are not prescribed. So, the powder producer fixes the condition in discussion with the applicator or final consumer.
To test weathering resistance of powder coatings is very important in powder coating application.