Re: Oil impregnation for bamboo
Good luck with the oil impregnation. The surface of Bamboo does not like to take any kind of stains or oils every well. You could use a Danish type oil finish, but it would need to dry completely. Otherwise you run the risk if you thread finish not adhering to the blank or developing fisheye due to the oil.
If we (builders) are going to use any type of material for impregnation we usually do it after the blank is glued up, but before the ferrules and tip top are installed. The impregnation usually involves a vacuum and sealed tube. Or you can soak it for several days and then allow it to dry for a couple of weeks.
If the varnish was cracked and peeling it was probably due to the rod being build many many moons ago. Old spar/shellac just did that. The newer spars don't seen to have the same issues. I pour my spar finishes and I have also used a hand rubbed Minwax Poly. Different types of finishes will not have any noticable affect of the rod's action.
As for the delamination: You can clean out any old glue with a dental pick or the like. Fill the deliminated area with something like Titebond III and bind the area with thread until dry. Remove the thread, clean up and finish. Do not use a two part epoxy like DevCon. It doesn't flex and the area will just crack and delaminate again. There are several heat set two part glue that can be used, think bow builders glue. But Titebond is also used to glue up blanks and works fine.
"Blessed is the fly fisher who's quiver contains grass, glass & graphite custom rods." Book of Rods 3:16