The phrase "to stain the top" means to leave a mark or spot on the upper surface of something, usually by accidentally spilling or smudging a substance on it. Full definition
Love the blue and white checked chairs, especially, but am also loving the wood stained top of the dresser combined with the painted bottom. (missmustardseed.com)
I thought I liked white bases with dark stained tops, but your beautiful table is perfect. (orphanswithmakeup.com)
I'm with you on stained tops over painted bottoms on furniture. (missmustardseed.com)