We have red cedar ceiling throughout our home. We applied clear oil based poly to it 25 years ago when it was installed. It has turned darker and more red than what we would like. Our goal is to lighten it back up and our question is there a practical way to do this?
Two things have happened; The polyurethane has yellowed over time and the wood has gained a patina. The only way to eliminate both of these is to sand till new wood and refinish. This is a lot of work and most likely wouldn't be practical.
If you decide to sand and refinish all of your wood ceilings, one room at a time is the best way to do it. Also, use a water based poly or acrylic urethane as the finish. These finishes resist yellowing.