Q. My company manufactures hospitality furniture. Some of our white painted cabinet doors are turning yellow, and we would like to figure out why this is happening and how we can fix it.—T.S.
A. This is a common observation with white painted cabinets. First we need to look at the actual finishing schedule. After the initial whitewood sanding, a proper primer coat needs to be applied and sanded. I typically try to stay in the same color family with my primer as the final paint combination. In short, you would not want to use a dark primer under a light finish as the color may show or bleed through to the final finish, resulting in a color change. Surprisingly, the type of final clear coat you apply can also contribute towards yellowing. Certain varnishes or urethanes, even though they appear somewhat clear, may actually be amber in nature, which will give you a yellowish cast. I would highly recommend a clear water-white acrylic conversion coating. This type of coating is formulated to give optimum clarity and non-yellowing properties.
However, even when you do everything absolutely right in production and the job looks perfect, there are other things that can contribute to yellowing after the product leaves your shop:
• Exposure to UV sunlight or radiation can potentially degrade color, especially if it is constant and intense. Many paint manufacturers use titanium dioxide as a component in the white paint to help block UV light in much the same way as the sunblock we put on before going to the beach. Some paint finish systems may also use glazes and clear coats that may or may not be as forgiving with the UV exposure, and subsequently contribute to yellowing over time.
• Although unlikely, cigarette smoke can yellow white cabinets as well, but the concentration of the smoke would have to be fairly high and constant to do this.
• Cooking or frying food can send steam, grease and other containments to the painted surface as well, and over time this could potentially yellow the surface.
• Surprisingly, cleaning materials can cause yellowing, especially if they contain bleach or harsh chemicals. A simple damp, clean rag used regularly over the surface is all that is needed to clean most of these surfaces.
Generally, most if not all of today’s paint manufacturers formulate their products to satisfy the rigorous standards of the Kitchen Cabinet Manufacturers Association. There are many factors that could be contributing to your yellowing issue, but to find out the cause for certain you should have some panels independently tested to help isolate and remedy this issue.