My car is original, I believe, and its got a thick black coating on all of the wood. It reminds me of oil base paint without hardener after about 3 days of drying. Its not completely hard, in places where its ran, you can still press your thumbnail into it. If its not original it was done before 1950 because I've documented it back to there. Have a feeling its done drying by now...!
For all of my SW Sedan top wood, I used 3 coats of tongue oil,letting it dry for two or three days ,paying extra attention to the end cuts. It is great for sealing out moisture.
Bruce Davis