Definition - What does Discoloration mean?
Discoloration is the process in which a coating applied to a material's surface changes color due to sunlight, air pollution, humidity or other environmental conditions. The coatings may be clear when applied, however with time they change color and become pale and discolored while still serving their intended purpose of preventing rust or corrosion.
Corrosionpedia explains Discoloration
Discoloration can occur with all types of coatings over time, however they are more prevalent in clear coatings and water-based primers that require sufficient curing prior to top coating, otherwise discoloration, low gloss and possibly delamination may result.
Clear coatings are ideally for copper and its alloys. Such substances have high corrosion resistance, but may form superficial discoloration over time due to handling and exposure to the environment. Clear coatings are used on surfaces in order to preserve their appearance. This type of coating can harden at room temperature or through baking.
Clear coatings offers other advantages such as:
- Complete protection against corrosion by providing a continuous film
- Fast application and simple preparation
- Personalized tinting is possible
- Usable throughout its entire shelf life
The serviceability of a clear coating depends on many factors, such as its ability to withstand sunlight after discoloration, and its resistance to air pollution, humidity and handling.