Preventing Burl Walnut from Going Dark During Finishing

How can I prevent burl walnut from going dark during finishing?

John Brock: Use a waterbased finish.

Carol Reed: Waterbased finishes, in my experience, darken the least.

Michael Dresdner: Most waterbased finishes do not darken wood the way oils do. They go on clear, not amber, and also stay clear indefinitely.