Natural Reflex vs Heated in Reflex

[SLIMBOB]

So, Brad had the post about loosing reflex, or taking set. The topic came around at one point, to heated in reflex vs natural reflex. I “believe” there is a difference, I would argue there is a difference, but is there?  How is it different?  Is it measurable?  Can you improve on heated in reflex (if there is in fact a difference) so that when done properly it is more like natural reflex?  Is one type more desirable than the other?  These questions have puzzled me, as I have not given the subject much thought. Interested in your thoughts.

[darinputman]

I don't have a whole lot of experience with natural reflex, as I'm not lucky enough to have staves that are reflexed the way I like. But I have tried to create that natural effect by gluing billets together at an angle and was really tickled with the way it held on a longbow I made in 2019, many shots later it still holds true. As a matter of fact I glued up a couple of billets last night at an angle and although I still plan on putting more reflex in with heat before I bend in the small curves I am hoping that the natural path the billets take from the splice will aid in a stronger resistance to set out to mid limb anyway.                               
   I don't believe there is anything I can do that will benefit my bows as much as getting them down close as possible to final tiller without overstressing the wood. But hopefully having that natural lay of the limbs will help also. I really look forward to hearing what others may have experienced on this subject, thanks for the post SLIMBOB

[SLIMBOB]

Well, I’m with you on the set issue. I saw where Arvin mentioned the same that I believe, and that is, to paraphrase, the less set the better. I sweat the tiller, painstakingly getting it right from the absolute beginning, and that is primarily to keep set to a minimum. Having said that, I have made bows from staves with natural backset. I love backset, but I have found it more temperamental than heated in reflex. Or so I would argue. Is it? Why?

[willie]

why? just a suspicion. A stave with natural reflex might be a stave with a tensionwood reaction, ie a stave with higher percentage cellulose rich cells and lower percentage lignin rich cells. (most cells are some mixture of both)  The lignins are like the cement between the rebars. the stuff that gets hard when wood dries or we heat temper, the stuff that prevents a cell from collapsing on the belly side under compression

[HanibalLecter(InnerSmile)]

why? just a suspicion. A stave with natural reflex might be a stave with a tensionwood reaction, ie a stave with higher percentage cellulose rich cells and lower percentage lignin rich cells. (most cells are some mixture of both)  The lignins are like the cement between the rebars. the stuff that gets hard when wood dries or we heat temper, the stuff that prevents a cell from collapsing on the belly side under compression

Too much lignin in wood makes it brittle though. Cellulose can only support so much polymer, it's nof like keratin.

[Selfbowman]

There you u go Willie. Talking over my head again. But I’ll stay tuned.

[Yooper Bowyer]

The only difference that comes to mind is what happens to the wood when it is heat bent?  Steaming is known to weaken wood, but dry heat is known to harden wood, but I really cant say.

[RyanY]

Seems like this question could be answered with some sort of bend test. Take a couple samples from a few trees, some with natural reflex and others straight to induce reflex. Measure how much load they can take before taking set. I wouldn’t be surprised if this varied quite a bit between wood species with some species’ natural reflex being more resilient. I can’t say I’ve seen a lot of bows built where people are claiming retaining a lot of natural reflex. But that could be my own internal bias. 

[willie]

I suppose there are different reasons a  stave has some natural reflex. I have always had a unproven suspicion that the less we torture an organic structure to meet our needs, the better it will work out in the end. Compressing a back fiber to create reflex, and expecting it to act just as efficiently as is did before in tension, might not be the best.
I do not think a stave that dried into reflex (that was not present before drying) counts for much, and there is a good reason for making a kink in the handle to create reflex also.
that said,
I believe most bends are held in shape by the integrity of the compression side. this is why a good toasting works so well.

slim has not said just what tempermental effects he is thinking of when he mentions his experience with natural backset, but reactionwood is generally avoided by most all woodworkers for that same reason.

what if one were to strap a caul to a living sapling and let it grow for a few years before cutting and drying, (drying with the caul put back in place after removing the bark)?

[SLIMBOB]

Willie. When I say natural backset is more temperamental, I mean they have been harder for me to hold together. I can add backset to the handle, heat bending with little or no problem. On some, some, naturally backset staves, the shape was eye catching. As were the splinters when it broke. I still like natural backset, just in moderation. I am aware of the argument concerning reaction wood and perhaps that is a part of it. I’m not sure one way or the other. I made a little plains style bow, maybe 25 years ago. It was made from a small limb so high crowned and narrow. 48 inches or so in length from memory. The limb grew in a near perfect arc, bending upward. 4 +- inches of backset. I was sure it would snap on me throughout the build. It had that feel to it. It never did. It held up and never lost its shape. I gave it away and so far as I know, it still has its shape. So temperamental. Different from heated reflex.

[HH~]

A lot of natural reflex comes out just bit cutting the profile of bow with out even bending it. Had one I'm working on yesterday, had 2.5" natural reflex in stave (not dried curve reflex) buit actual in tree. I profile bow on saw and checked it, (blank has never been stressed now just cut). It now retains 1. 3" of reflex. So, on the caul it went. I'm thinkin with a good slow tiller and getting a string on it while its heavy I can possibly retain 3". So, what I think use both Natural and some man made reflex and yer in good shape.

HH~

[paulc]

Surely the conditions under which the tree grew will effect the characteristics of the wood...a hickory grown is GA will likely be at least a bit different from a hickory grown in upstate NY giving different performance..?
P

[SLIMBOB]

I can’t speak to Hickory, but Bodark has some regional peculiarities. It tends to be thick ringed and lots of early wood here in Central Texas. North Texas along the Red River, much better.

[loefflerchuck]

I've found for self bows that sometimes woods like hickory and Siberian elm that season into a reflex make a faster bow than one reflexed by heat. That is obvious to most people. If it is in the tree then it will depend on it being a conifer or hardwood. Reaction vs compression vs tension is not the same thing in those woods. If a bow is backed with sinew, a stave with natural deflex can be made shorter, then strung backwards before backing it to give it a sinew induced reflex. This engages the sinew more and puts the wood under less strain to make a very efficient bow.

[bassman211]

If you have a small tree, or large sapling that has a lot of natural reflex, and you split it to make two bows your left with one stave that will have that much deflex. I put both those staves on the same form to shape them, and build the bows. Fire hardening  the deflexed stave will still make a nice bow.