We have a porcelain vanity top that was installed in 2005. After about 1 year, the porcelain in the sink started developing hairline cracks. They are cosmetic and appear to be in just the top "glaze" (if that's what it's called), but now there are 20+ individual cracks and they are impossible to clean.
There are enough there that we are thinking of replacing the vanity. What causes these cracks?
Is there a way to clean them to make them less noticeable? The vanity is white, the cracks are brown and get darker between cleaning. I've tried bathroom cleaners (Mr. Bubble) and even straight bleach without effect.