Reminds me of the day I got detention as a six year old.
I got in a fight with another six y/o over who got to go first in a queue or something equally trivial. I shoved him into the ink cupboard. The cupboard door recoiled and the contents, several bottle of Quink, came tumbling out and spilt their contents on the wooden floor.
Our punishment was to clean the floor. It was as in a nightmare... the more we wiped at the spill the more it seemed to spread until we were rescued by the school caretaker.
Afterwards, the bits of floor where the varnish had been worn by countless little feet carried a stain just like the one you've worked on so hard! Beautiful, it was. It may well still be there in Olney Primary School (as was in 1968).
It's not the way to refinish a bass though. I like your method much better.
Great work! It looks lovely.