To prevent water stains from forming on wooden folding TV trays, one of the best things to do to protect the wood is to apply a layer of a protective finish. Various finishes can be used that are extremely effective, including varnish and lacquer. In addition, most wooden TV tray models already come with a sealant pre-applied, making the piece resistant to staining and preventing water rings.
If your wooden folding TV tray does form water stains, there are ways you can remove them from your furniture. First, mix equal amounts of olive oil and vinegar into a small bowl. Next, use a soft cloth and apply it to the water stain, wiping in the direction of the wood grain until you have removed the stain completely. This mixture is multi-functional, with the vinegar helping to remove the stain, and the olive oil acts as a furniture polish.