boo backing - do you have an outie or an innie??

[TargetSlayer]

When backing a bow with boo, I know many (if not all?) bowyers use the outer surface of the bamboo slats (what was the shiny outside of the plant while whole) facing out as the exposed back of the bow. Is this always the case, or do some people flip it? I don't mean using the bamboo as the belly, I mean flipping the bamboo backing so the fibrous inner plant part is facing outward as back. I know the nodes would be a little more stubborn to sand necessarily flat to laminate inward, but some evidence of nodes could be preserved for looks on the exposed bow back by not sanding the remnants of the inner node disks completely, and in fact from some photos I'm not convinced it's never done sometimes, as counter-intuitive as it would seem at first glance...?
*The reason I ask is The Bowyer's Bible Vol. 4 states that plain 1-piece bamboo billets (or even in the case of a thick 1 piece bamboo self bow) are always to have the, "lignin-rich outer (bamboo plant) surface as BELLY, while fiber-rich inner surface as back"... and I'd seen other references to tensile vs. compression properties indicating bamboo should be used in this intuitively backward fashion.
Is this only for simple, single-piece bamboo billets or boo self bow limbs, and is contraindicated when laminating the bamboo as backing?
I did notice at least one nice-looking boo-backed-boo build (again, if not all correct bbb's) seemed to use the plant's original outer surface (i.e. not glued inward) for both the belly and the back, but while extra heat tempering the belly to facilitate favorable compression properties.
So again, maybe the Bowyer's Bible tension vs. compression = inner boo fibers face out on back is just when you're not laminating the boo to anything else, and only then? Or do some place inner boo fibers outward as back, ever, on any laminated bows due to this compressable lignin vs. tension-able fiber consideration?
Any thoughts on this would be extremely welcome, and thank you in advance.

[DarkSoul]

If you ever try bending a slat of bamboo in both directions, it becomes immediately obvious why we use the outer surface of the bamboo as the back of the bow. The inside of the pole is very brittle and starts making cracking noises as soon as you subject it to tension.

[TargetSlayer]

Thank you for your reply. So I take it I'm safe to assume I should always back bows this way (outer bamboo facing out on bow's back), but I was still puzzled (esp. after you're asking me to demonstrate this with plain bamboo) why on page 152 of The Bowyer's Bible Vol. 4 a world class craftsman, researcher, and writer says either plain bamboo billets, or a thick bamboo self bow should be just the opposite, again claiming lignin-rich outer boo compresses better as belly and the fibers take tension better as back.
I think I've found my answer playing with some of the thick, lumber/timber size bamboo I was lucky enough to harvest and split from a nearby swamp it somehow got started in.
If one shaves and sands down the inner fibers to tiller or meet whatever specifications, using the inner fibers as exposed back would do as you say and peel up.
But the author must be referring to primitive, quickly made, or survival plain split bamboo bows that are not tillered by reduction of thickness. After being split, these examples seem to have been only tillered by shaving the sides, width only and not thickness -- then the fibers don't start and stop all over the place on the inner bamboo surface (conversely used as back in this application) -- rather, they are unbroken strands that run the full length, with the exception of some from tapering the flattish bow only on the sides... and his only recommendation there is to leave no raised sides from the natural curve of the cylindrical plant. There are pictures of a couple plain, unlaminated bamboo bows, one with impressive fps stats etc. for its specs., with inner bamboo fiber used as back. I do have enough bamboo now that, despite my main intention to back bows with it, outer bamboo surface used facing out as back like appears normal (this is a next progression for me as my only two this far have been self bows) -- despite this I do have enough to try a bamboo self bow with the abnormally thickest bamboo timbers, and I was going to instinctively use the outside of the boo as back until I read this pg. 152, saw those, and the "science" behind them, which got me on this question.
Thanks again -- I guess the best way would be to make a self bow of each for experimentation, as that leaves me, still, many lengths for my main boo-backing next project. I now know to invariably use the outside out on back when laminating, at least

[Pat B]

If you look at the end grain of a piece of bamboo you will see it is made up of fibers. The closer you get to the outside of the culm the smaller in diameter and more dense these fibers become. The ones closest to the outside are called the power fibers and for good reason.

[Prarie Bowyer]

There is no need to reinvent the wheel. 

the only thing that is good on the bamboo is the thin dense layer of fibers.  So to flip it you you need to sand those off because of the crown.  Also the nodes need to stay on for backing.  They can come off for a belly but a back MUST have them.

I actualy remove as much of the inner wood as possible. . . mostly.  Sometimes I get createive withteh density to help fill out a nosed profile.  I use a jack plane with a scrub plane blade in it and hog off the inside till it's flat.  then I trace the precut belly piece on it and cut that out.  Then I use a large diameter 50grt drum sander and grind it till it's about 1/16" thick at the edge or I see the dark hard fibers starting to peek through.  The rest is trash IMO.

[Youngboyer2(billyf)]

Make  sure that you wear a mask when working lots of bamboo, I sanded lots of bamboo arrow shafts and had a cough for a few days, I have also heard that it can cause long term damage to your lungs.
Very good and flexible material, good for lots of things 

P.S. Welcome to PA targetslayer,
Starting things off with a question is a good sign

[M-P]

Target Slayer,  I did not go back and re-read TBB 4, but yes some excellent bamboo selfbows are made with the outside of the bamboo used as the belly.   I'm specifically thinking of the  traditional Bhutanese bows. The most dense portions of the bamboo are those "power fibers" just under the rind.   That makes them by far and away the best part of the the bamboo to resist compression.  The inside of the bamboo is not as strong in tension, but it makes a really, really  bad belly.   So for a bamboo self bow you use the outside as the belly and the inside for the back.  It's not ideal but a workable compromise.
When used as a backing, you're only concerned about resisting tension and that means using the outside of the bamboo as your back.
Ron