As I explained before, polyurethane does a pretty good job in this department. It will prevent the natural chipping process that paint would normally show. You see, a large part of this chipping is caused by contact with the elements. Virtually all free-floating air contains some tiny amount of water vapor. Temperatures will cause all paints and finishes to expand and contract. We are talking about a very tiny movement here, but it’s enough to create cracks over a long period.
As if that weren’t bad enough, sunlight will also cause a certain amount of paint degradation. To be more specific, the sun’s UV rays are actually a form of low-level radiation that can do unseen damage to your paint job. For cabinets that are located in very sunny kitchens, it is essential to choose a product that contains UV blockers of some type. These are chemicals that are added to clear coat products. They are designed to reflect UV light, keeping the paint underneath from being damaged.
Polyurethane will prevent all of these problems, at least until the clear coat itself is worn away. For cabinets, a piece of furniture that is not generally exposed to harsh conditions, a good clear coat job should last for years. Depending on how many coats you used, you can expect your work to last for 10-20 years. Again, oil-based finishes tend to be on the higher end of that spectrum. You can get around this problem by simply using more coats.