There is NOTHING that coats a tube as well as polyurethane /expanding adhesive (Poly-Gorilla glue) if the drawbacks are overcome.
1. Not ALL "Gorilla" glues are expanding poly, so know or learn the differences.
2. Wear GLOVES.
3. Coat the tube and plug the ends
4. After inserting into the blank, TAPE both ends, or the expanding foam CAN force the tube partially out of the blank!!!!!!!!!!!!!
5. Wait 24 hours for it to foam up and cure.
CAVEAT: I am not suggesting that this should be yours, or anyone's primary method. I'm just saying that if complete coverage is needed, it is one method that will do it well. Extremely well. One advantage of this is that on some segmented blanks, it adds strength to the blank when one is afraid the blank might explode. Don't trust CA on critical segments, use epoxy or poly.
> And a caveat to that is that if there is a minuscule hole in a segmented blank, the expanding foam will find it and leak out - ruining the looks of an otherwise beautiful blank. As for me, I have taken my chances and survived with some well crafted segments.