A.Michael Dresdner, a professional wood finisher in Puyallup, Wash., and the author of Wood Finishing Fixes, responds: Depending on what the painter used to bleach the wood, it's possible that residue from the bleach reacted with the stain. Most bleaches will denature dyes, and some brands of stain use dye as one of their colorants. Because bleach affects various colors of dye at different rates, it may well have lightened some of the darker tones and left the yellow component intact, resulting in the yellow hue you describe. When you use bleach, it is always a good idea to either neutralize it or wash off any residue if that particular bleach leaves one.

Another possibility is that the wood itself turned yellow, which, since it is so difficult to see true colors on sanded raw wood, the painter didn't notice until it was stained. Certain bleaches are known to lighten most woods while turning others — especially some softwoods — slightly yellow.

By now, the stain is dry, and that means the wood is at least partially sealed. At this point, your best bet is to add stain selectively to the yellow area to try to blend it to match the color of the rest of the ceiling. If you recall basic color-mixing rules, colors on opposite sides of the color wheel tend to neutralize one another. For yellow, that color is purple. As odd as it sounds, a stain with a very light purple hue will ameliorate the yellow and blend it back to beige or brown.