Popular wisdom has it that inset panels should be stained/dyed before building the frame in order to avoid witness lines as the wood moves with ambient humidity. But switching to water-based dye, I just discovered that panels can be safely colored after construction, as capillary action will readily move the dye well into the covered portions--all the way to the very edge of the panel! This may not work with more viscous stains. Water-based dyes also avoids the whole splotchiness business since wood is quite good at absorbing water, no need to wipe. In my case, I am dealing with cherry dye on maple. I don't quite have my TransTint formula perfected, but I am getting close.
I am sure this has long been obvious to most, but I just discovered it and thought to report it in case a similarly daft person is pondering this very issue...
Cheers, Shawn
PS: I also discovered that large "catheter" syringes and a few mason jars takes all the mess out of dealing with finish.