There isn't a strict limit to the number of coats of paint you can apply to kitchen cabinets, but there are a few factors to consider when determining how many coats are appropriate. Here are some points to keep in mind:
Thickness: Each coat of paint adds thickness to the surface, so you'll need to ensure that the additional layers won't cause problems with the cabinet doors or drawers closing properly.
Smoothness: Adding too many coats of paint can result in a buildup of layers, which may affect the smoothness of the finish. Excessive coats can create a thick, uneven surface or make details and wood grain less visible.
Durability: Applying multiple coats can enhance the durability and longevity of the finish. However, keep in mind that the quality of the paint and application technique also play a significant role in the overall durability.
Time and effort: Applying multiple coats requires more time and effort, as each layer needs to dry before applying the next one. Consider your available time and patience for the project.
In your case, since you mentioned there are already three coats of paint on your cabinets, you should carefully assess their condition and determine whether additional coats are necessary. If the existing paint is in good condition and there are no significant imperfections, you may not need to add more coats. Instead, you can focus on properly preparing the surface and applying a new paint job to achieve the desired color and finish.
Remember, thorough surface preparation, including cleaning, sanding, and priming, is crucial to ensure proper adhesion and a smooth final result. If you have concerns about the yellowing and cleanliness, consider using a high-quality, stain-resistant paint specifically designed for kitchen cabinets to minimize these issues in the future.