Jon,
Try the tung oil without taping the spine. I apply the tung oil with my fingers and on the first application I keep adding tung oil in order to keep the wood wet for about 30 minutes. Then I wait 10 minutes and hand buff. This will remove the oil on the spline and surface of the wood. I then let it dye for 24 hours. Then I will put another light coat of tung oil on, wait 5 minutes, hand buff, and let dye for a couple of hours. I will do around 5 coats like this. Then a really quick machine buff without compound. With oil finishes you want them in the wood not on top. I only use this method on wood that are not porous or oily. Works great on osage and stabalized woods. With walnut you need to wet sand in the tung oil. With woods like cocobola I seal and sand several times with thin ca glue and different grits up to 2500 grit and only added two coat of the tung oil at the end using the first method I described.
James