Plant fiber backing questions

[Aaron1726]

Hi all, I'm curious about plant fibers, more specifically dogbane, as a backing.  I've messed with it once before, but no idea if I did it right.  For anyone that's done something like this, what was your process for application?  And how thick did you get the fibers?  I appreciate any experience yall could share.  Thanks

[bjrogg]

I’m sorry I can’t help. The only thing I ever backed a bow with was rawhide.

I saw the post you put the dogbane on and it looked like you did a pretty decent job of it.

I have know idea how it works.

I’m thinking if I were to go through that much effort I would probably use sinew instead. It shrinks tight and has elastic qualities.

Let us know how you like it

Bjrogg

[joachimM]

I use plant fibers quite a lot, mostly flax and sisal.
Flax is easily available here (Belgium), and we have really excellent quality.
Sisal is a bit coarser, but also more elastic. We have single ply hay bale cordage that I untwine, wash and comb, cut into 25-30 cm pieces or so, and apply onto the back with hide glue just like you would do with sinew. It needs to be quite a bit more tacky for sisal than for sinew.
I generally pull the bow into reflex for sisal, to pre-tension the fibers. Not for flax.
After it has gelled I wrap the bow with bicycle inner tube very tightly and I heat it with a heat gun to liquefy the gelled glue and press out the excess glue from between the inner tube wrappings.
This works fine for me.

See earlier post here
http://www.primitivearcher.com/smf/index.php/topic,52986.0.html
I've built a handful of sisal-backed bows meanwhile (works really well with elm!), will shortly back a few more.

[Aaron1726]

Thanks for the replies guys!

joachimM, that is very interesting about the sisal.  I wound not have thought of it being stretchy like that.  I have a spool of sisal twine in the garage I use to tie up tomatoes, I think I might have to try it out!  My method for the dogbane seems very similar to yours for the sisal just that I used tb3 instead of hide glue.  I also didn't add any reflex, I assume dogbane would be similar to flax from a stretch standpoint?

I understand that its not gonna beat sinew, but from a learning standpoint I feel better using the plant fibers on my less than great bows I'm doing right now.  I will be saving up sinew for when I feel I've made a bow worthy of it 

I will keep at this one with the dogbane and post how it turns out.

 Thanks again

[willie]

I untwine, wash and comb, cut into 25-30 cm pieces or so, and apply onto the back with hide glue just like you would do with sinew. It needs to be quite a bit more tacky for sisal than for sinew.

Joachim, do you soak  or soften the sisal before application with the hide glue?

[joachimM]

Willie, washing will soften the fibers, but before application I soak them of course in hide glue, which softens them again. It's pretty easy, but the hide glue needs to be tacky like hot maple syrup.

 

[bjrogg]

Aaron you might try trading some dogbane for sinew. Always interesting seeing how much knowledge is being shared on this site

Bjrogg

[richgibula]

Here in AZ we don't see that much dogbane but we have a lot of waste from Sotol and agave plants in landscaping. Their fibers are extremely strong. The leaves have easily separated fibers that were used by Native American in years gone by for sewing.

I have separated these fibers to make cord but I don't think they are strong enough for bowstring. The longest fibers I got out were almost 2 feet long. It should be as strong as sisal fibers, which is a kind of agave, I think. I also tried Blue Agave (Century Plants) but their fibers are really stretchy.

Your bow looks great. Please keep us informed as to how this backing holds up under use of the bow over time.

[Aaron1726]

Aaron you might try trading some dogbane for sinew. Always interesting seeing how much knowledge is being shared on this site

Bjrogg

Thanks, that's a good idea.  I may try to harvest extra this fall and see if anyone is interested.

[Aaron1726]

Here in AZ we don't see that much dogbane but we have a lot of waste from Sotol and agave plants in landscaping. Their fibers are extremely strong. The leaves have easily separated fibers that were used by Native American in years gone by for sewing.

I have separated these fibers to make cord but I don't think they are strong enough for bowstring. The longest fibers I got out were almost 2 feet long. It should be as strong as sisal fibers, which is a kind of agave, I think. I also tried Blue Agave (Century Plants) but their fibers are really stretchy.

Your bow looks great. Please keep us informed as to how this backing holds up under use of the bow over time.

I've not tried agave, but have used yucca quite a bit.  It makes strong cordage, but as a bow string it was really hard on the fingers, it's very abrasive.  I may have to see how stretchy it is, might be similar to the sisal. 

Never messed with sotol or agave, but if the agave is that stretchy I'm now curious if it would do like the sisal. 

I gotta make some more bows and give some of these a try

[richgibula]

The names are a bit confusing. I looked it up and yucca, sotol are species in the agave family. The blue agave fibers are like rubber bands in the plants I harvested them from.

Regular yucca and sotol fibers are very similar except that sotol are a little longer unless your yucca is huge.  I use whatever I can get my hands on. I wish I had some kind of power rollers to crush the leaves to separate out the fibers faster without damaging them.  I would bet that these long fibers would also make good paper, too.

[WhistlingBadger]

Interesting stuff, guys.  I've been working some dogbane fibers--something relaxing to work on while the family watches TV.  Might try backing that chokecherry molly bow I've been dreaming of. 

I can't remember who, and I'm at work right now so I can't look it up, but somebody in one of the TBB volumes suggested that plant fiber might actually be superior to sinew, because it does the same thing but is lighter in weight.  He was thinking of flax and milkweed, if I remember right.  I'm a little skeptical about that.  If plant fibers were better than sinew, I think the natives would have been using it.  Still, dogbane is strong stuff, so it should at least keep a bow from exploding, and maybe even increase performance.  It's a lot easier to get than sinew, too--growing all over the mountains, free for the taking.

[joachimM]

I can't remember who, and I'm at work right now so I can't look it up, but somebody in one of the TBB volumes suggested that plant fiber might actually be superior to sinew, because it does the same thing but is lighter in weight.  He was thinking of flax and milkweed, if I remember right.  I'm a little skeptical about that.  If plant fibers were better than sinew, I think the natives would have been using it.  Still, dogbane is strong stuff, so it should at least keep a bow from exploding, and maybe even increase performance.  It's a lot easier to get than sinew, too--growing all over the mountains, free for the taking.

Sinew is more rubber band like: it can stretch easily 5% (wood at best 1%) but it's also more easily stretched than wood: its modulus of elasticity is 3 to 5 times lower than that of wood (it takes 3 to 5 times less force to stretch it a give percentage), while having a higher density. But the advantage of sinew is that you can stretch the hell out of it, and it shrinks as it dries, putting the belly under tension.  It's advantageous in short bows where the back is strained far beyond 1%. If the back isn't strained >>1%, sinew is just dead weight making your bow sluggish.
 
Plant fibers on the other hand are much stiffer (modulus of elasticity of flax is 50 to 70 GP, compared to  2.7 GP for sinew and 12 for osage and 15 for hickory, just for reference), and although some plant fibers can stretch (allegedly) more than 3% (like sisal), they don't shrink like sinew as they dry.

It was Tim Baker who lauded flax as the ideal backing (for regular long bows), as it behaves like incredibly strong wood that you can mold as you like, and apply easily wherever you want.

But since flax is so strong in tension, it can easily overpower the belly of a bow.
So summing up, sinew and plant fibers can both shine or be awful as backing material, it all depends on the design of the bow.

[bjrogg]

I can't remember who, and I'm at work right now so I can't look it up, but somebody in one of the TBB volumes suggested that plant fiber might actually be superior to sinew, because it does the same thing but is lighter in weight.  He was thinking of flax and milkweed, if I remember right.  I'm a little skeptical about that.  If plant fibers were better than sinew, I think the natives would have been using it.  Still, dogbane is strong stuff, so it should at least keep a bow from exploding, and maybe even increase performance.  It's a lot easier to get than sinew, too--growing all over the mountains, free for the taking.

Sinew is more rubber band like: it can stretch easily 5% (wood at best 1%) but it's also more easily stretched than wood: its modulus of elasticity is 3 to 5 times lower than that of wood (it takes 3 to 5 times less force to stretch it a give percentage), while having a higher density. But the advantage of sinew is that you can stretch the hell out of it, and it shrinks as it dries, putting the belly under tension.  It's advantageous in short bows where the back is strained far beyond 1%. If the back isn't strained >>1%, sinew is just dead weight making your bow sluggish.
 
Plant fibers on the other hand are much stiffer (modulus of elasticity of flax is 50 to 70 GP, compared to  2.7 GP for sinew and 12 for osage and 15 for hickory, just for reference), and although some plant fibers can stretch (allegedly) more than 3% (like sisal), they don't shrink like sinew as they dry.

It was Tim Baker who lauded flax as the ideal backing (for regular long bows), as it behaves like incredibly strong wood that you can mold as you like, and apply easily wherever you want.

But since flax is so strong in tension, it can easily overpower the belly of a bow.
So summing up, sinew and plant fibers can both shine or be awful as backing material, it all depends on the design of the bow.

Very interesting and explained well. I never thought of it like this but I suspect you are on to something here.

One other problem with sinew is keeping it dry in a wet humid environment. It really likes to absorb moisture and then it loses its effectiveness. I guess I shouldn’t make that statement as a matter of experience, more from what others have said but it seems to make sense.

Love how much knowledge and experience is shared on this site

Bjrogg

[Aaron1726]

Thank for all the good info guys!  I have been inspired enough that I picked up a new spool of sisal and a 2x2 oak board from the store yesterday to play around with. 

The dogbane bow is coming along, I will get some picks up on that one too when I get a chance.

Thanks again for sharing yalls knowledge, it really helps those of us wanting to learn this stuff.