Where to cut yew

[WillS]

Yeah it's tricky.  Personally I've always called anything that isn't obviously "bark" or "sapwood" cambium.  Whether that's fibrous stuff, or pickable bits of softer stuff makes no difference to me.  That's clearly not scientifically correct, but I'm not sure quite why it would matter.  As you say, as long as we and whoever we're talking to understands, that's all that really counts.

[tannhillman]

It states in the work done on the MR bows (by Hardy I believe)  that there are traces of cambium on the back of some of the bows.
Your picture of your Pacific Yew warbow is typical of a bow that hasn't had any the sap wood taken down to reduce it's thickness and....
a) Hasn't been meticulously cleaned up. No criticism is  implied as I believe that's exactly what they are talking about on the MR and many of my bows show the same, unless I am being obsessive in prettying them up.
or
b) Hasn't been tillered with the 'underbark' left on to allow it to pop off in one piece, which gives a virtually perfect surface.

I think the main problem with this thread is twofold... one the naming of the layer above the sapwood, as the Hardy MR reference refers to both bast and cambium and I take it the mean the stuff visible in your pic (which in my experience is homogeneous with the thicker corky layer which pops off). It doesn't really matter what we call it in terms of seasoning wood and making bows as long as we understand what we mean.
The other problem is the different experiences with Yew. It is up to the reader who's opinion and advice they take.
As always I only ever offer my first hand experience, and I have no problem with people ignoring it or preferring the experience of others.
I shall in future use a generic rather than specific name for the corky fibrous underbark stuff that pops off.
Del
BTW... nice looking back
[/quote 
That might be a little bit of cambium and inner bark left behind on your bow there.  It is vey hard to tell from those pics of MR bows if the cambium is on them or not, for a start the pics are quite yellowy orange so similar to the colour of cambium. And after 400 years in the sea I think the colour has merged somewhat! I have uploaded some pics of some of my bows, the cambium is quite obvious

[tannhillman]

And other one 

[tannhillman]

That's the cambium. And left on gives protection to the sapwood and, in my opinion, makes for a stronger bow:)

[PatM]

When are you cutting that wood?

[WillS]

Well whatever it is, you won't see that much of it on any MR bows, or indeed on any of the replications of those bows.  You might find "traces" in dips and around knots, but to leave an entire layer on is extreme.  All it really does is show that the rings haven't been reduced.  The whole point of the sapwood is to protect the bow from breaking.  If you're adding more stuff on top of the protective sapwood to protect the sapwood, you might as well then sinew over the top, to protect the protective layer protecting the protective sapwood...

[tannhillman]

I'm not 'adding' anything. . I'm not removing / retaining the existing very thin and durable cambium layer and also not undermining the strength and integrity of the bow by removing some of the sapwood! t

[PatM]

Could you respond to my question as to when you are cutting the wood?

[tannhillman]

Sorry missed that one, in the late autumn /winter/early spring. How about you?

[PatM]

Whenever the tree is not actually growing. When was the one cut that is shown in the picture?

[tannhillman]

There are three bows in the pictures, but sometime during the period I mentioned. I get some wood from tree surgeon contacts and that can be cut anytime of year, depending when they are asked to do the work.

[PatM]

And how thick do you think that "layer" is?

[tannhillman]

If you mean the cambium .. I've just measured a bit with my digital calipers iv just scrapped off an off cut and its 0.25 of a mm .

[WillS]

So you're choosing to leave a piece of the inner bark on the bow, despite the fact that it's pretty ugly and has no historical bearing when it comes to what we know about warbows because it's protective - at 0.25 of a mm?  Seems a bit odd.  Not trying to gripe or cause an argument (there are easily enough of those surrounding warbows in particular so apologies in advance if I'm coming across abrupt!) it just seems really odd.

It reminds me of a thread a while ago that was on the EWBS forum.  Somebody had found a guy trying to sell his longbows on eBay and he did what you do - left the "cambium" (or whatever it's called) on the back, saying that most of the MR bows had it.  The general consensus amongst the warbow guys (and we're talking the really top talented bowyers such as Joe Gibbs et al) was that it was totally pointless.  None of the MR bows have it (unless you count bits left in dips etc) and most of them said that they'd much rather have a bow with the thinnest possible sapwood that had been chased and reduced to a single ring so the bow itself performed faster, as compared to leaving a soggy strip of something just to show that the sapwood hadn't been worked down at all. 

In fact (and this is second-hand information so take it or leave it - I don't have anywhere near enough experience to say whether it's true or not) I've been told by at least two bowyers who I really look up to at the highest degree that the best thing you can do with yew sapwood that doesn't need to be thinned per se is reduce it down to the first yellowish layer, rather than the brighter white stuff.

At 0.25 mm it's probably not doing a thing for strength, but it's more likely just a preference thing, and if you prefer that weird brown stuff covering what would be a stunning white back then that's your call

I still think however, that trying to differentiate terms between bast, cambium etc is a bit over the top.  Bowyers will know what you mean if you say cambium - I think to most people who make bows, you have the bark, then the cambium, then the sapwood.  It doesn't NEED to be more complicated than that, otherwise we might as well start using latin names for everything and being all elitist when somebody asks us how to treat rot in heartwood and telling them that rot doesn't exist, and the area they're referring to is actually xylem. 

[PatM]

If you mean the cambium .. I've just measured a bit with my digital calipers iv just scrapped off an off cut and its 0.25 of a mm .

That's what I don't get. You say it comes off when the bark is dried in place and popped off later , but why would it not just come off later if the bark is removed when the stave is green?
 I'm looking at the part where you have rounded the back near the horn nock and the color on the back looks like nothing more than oxidized sap rather than an actual layer of material.