I,m an exotic wood fanatic and use a lot of black wood in nearly all my pens for center bands,accent rings and laminating etc.Black wood is probably the oiliest wood you can get and doesnt like to adhere to most other timber and especially if you use coloured bottle caps for accent rings.
Dont TRY this. Just DO IT. Soak the piece or complete blank in a small tin
with laquer thinners in it .Make sure you cover the whole piece and straight away you will see how the thinners draws out the oil.the thinners will actually start turning black quite quickly.For a small section like a center band 15 minutes will be fine.Then put on the bench till the thinners
evaporates.Use any brand laquer thinners from the local hardware .
Polish to a beautiful shine and maybe for the first time you will see those exquisite amber lines come through.[ no more plastic look]
C A coating works a treat.My early pens used to crack at the joints and part after about a year . Not good if you give a guarantee .
All the best and cheers for now.
Ivor.