Color of paint and coating may appear differently when dried completely as compared to their liquid state. It might have more shinning effect in liquid state which may fade out after complete drying. This is why paint industries are employing hot air ovens to test the post-drying appearance of the coating. Also, this machine can pace up the whole drying process.
Paint or enamel comprises of many ingredients, it’s a combination of liquids and solids which are processed together to form a fluid of free-flowing consistency. There are some volatile ingredients in the paint like thinner, solvents, reducers etc. These ingredients leave the paint after application. Another important component is the binder which forms a hard film to provide a final finish of the coating. For achieving the final finish, a paint goes through three stages; drying, hardening and curing.
Drying is the stage when solvent or thinner or water evaporates from the paint after the application
Hardening is the stage after reducers leave the paint and binders come into action. Binder solidifies and hardened into a solid film.
Curing is the final stage which is the combination of both drying and hardening. This is quite a longer process than drying. As solvent gets evaporated in very less time, whereas pigments take its own time to get that surface finish depending upon the environmental conditions. If not cured properly, the surface will lose its finish and creates an uneven appearance. E.g. Nail enamels. The thinner gets dried up quickly but the binders take the time to form the layer of thermoplastic polymer for a smooth finish. Sometimes, when the pigments solidify, they may change the appearance. To assess the final shade of the paint, it becomes important to speed up the curing process.
Curing can be done naturally or accelerated by simulating the conditions in the controlled environment.
A hot air oven can be used for this job. As already mentioned that thinners don’t take much time to get evaporated. It’s the binders that need acceleration for pacing up the process. This machine creates a controlled environment where the temperature can range from ambient to 250°C. Fans are used to circulate the air throughout the chamber for uniformity. As this device can be customised on request depending upon the industrial requirements, its usage is extended to many curing applications. It can be used for testing of the color of samples, to estimate the complete drying process of the sample in the application, to estimate the drying time of paint when left open and unused.