Jim - the trick with sanding sealer on oak is to dilute it. about 2:1 - use it neat and it does have a tendency to scratch off. Dilute it, apply with a brush, (lathe stopped) then rub it in with some tissue, which at the same time wipes it off. That way it absorbs more in to the wood and binds with it, rather than just sitting on the surface.
Those black marks you've got at both ends of your barrels are transfer of metal from your bushings in to the grain. Better surface finish will help eliminate it in the first instance, but as I said earlier, use a tack cloth (lathe stopped) after your final sand, which will get rid of the rest of it.
Lots of people here have methods and opinions on how to stop transfer from bushings, but short of turning between centres (which is tomorrow's lesson
) they mostly require some form of hardware alteration part way through, and for me, with one eye on the clock, its never going to happen. Use a tack cloth, the turner's best friend and you'll be sorted. (which reminds me, I need to get some more)
