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I am looking at a stika spruce top, it says that there is some compression, a thin pitch streak and grain runout. Each piece measures 7/16 x 8-3/4 x 22". Growth rings per inch are 13 at the widest and 17 at the tightest. will the runout and pitch streak make a difference in sound, and integrity of the board???

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I am looking at a stika spruce top, it says that there is some compression, a thin pitch streak and grain runout. Each piece measures 7/16 x 8-3/4 x 22". Growth rings per inch are 13 at the widest and 17 at the tightest. will the runout and pitch streak make a difference in sound, and integrity of the board???

I will assume this is for a flat top acoustic(regular acoustic guitar* domed/radiused top and not a carved plate). I will give you the skinny on each item you mentioned.

Comression. This is referencing the wood that grows around a limb or other point of focused stress(could be the lower part of the trunk). These parts of the tree develop "reaction wood" which refers to the part that becomes more comressed on the part taking the heavier load, and tension wood that is on the opposite area that is being pulled on. You wind up with a difference in the density in these areas because the tree tries to strengthen itself as needed to adjust for the load. It is also possible micro fractures and other defects can occur. This is something we try to avoid or limit as much as possible.

Thin pitch streak. Pitch pockets that are large can have negative effects on strength and sometimes create finishing problems. Very small pitch pockets may be less of an issue. Large pitch pockets are problematic, and should be avoided.

Runnout. Runnout does have a negative effect on strength(ability to resist load before failure). When you have more than 2-4 degrees you rapidly lose strength. The test I have run show me there is also a reduction in stiffness when all else is equal or extreamly similar(testing wood cut from the same very homogenuos billet, with the only notable difference being runnout introduced by cutting to increase or minimise this). Loss of stiffness at the same weight is less desirable, loss of strength is unacceptable(failure will lead to repair work, if the fractures are repairable).

Growth rings. The number of rings and or size becomes a factor because early wood and late wood are very different in strength and density. Early wood is the lighter colored part of the rings. It grows fast with lots of moisture and is much less dense and strong compaired to late wood(dark rings). The overall ratio of late to early growh is really what is important. The more late wood the denser and stronger it will be. This is why many seek wood from that grows more slowely at high elevations where moisture is often frozen much of the year and less available to the tree for growth. You also should onsider ring spacing, as very wild swings from wide rings to skinny will give you wood with less balanced strength/stiffness across the board. Very large differences may lead to focused stress in areas instead of spreading it about the top more evenly.

As far as sound, yes all these things effect sound or performance. The way you brace, set the thickness, design of bridge and on and on also effect the sound or timbre. So you should think of the differences in these terms. Will it make the soundboard less predictable for my style of build and my experience(if you are used to building with wood that has some common charictoristics, you will have more predictability. Will the wood reduce efficiency, there are differences in efficiency and the way wood will react to stress. Will the top last and remain stable, this is HUGE. Really if your work fails because of a strucural flaw that would really suck.

FWIW; A Sitka soundboard with flaws like this has VERY little value. If you are trying to figure out the worth(given it does not exceed reasonable runnout levels or flaws that compramise structure) the wood is likely worth $5-7.50. Student grade soundboards have very little value, but MUST still be structurally be sound to demand that high of a premium(note; your talking about charging about $15-20 bd. ft. for that Sitka, and Sitka is normally valued at about $5-7 for good lumber grades, YOU ARE PAYING A PREMIUM). The higher priced soundboards base ALL that value on the difficulty in finding wood that meets the specs that meet the demanding requirements. Seek out $15 to 45 dollar sets (2A to 3A-These are top notch structurally and are usually not too bad visually), these are the best value for your projects. If you want to play with some sets or practice/test buy lower student grade in the $5-$12 range. Avoid getting too hyped up on "master" unless your customer wants visual grading factors to be highly important(bragging rights).

Luck,

Rich

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thanks Rich for your help. i was looking at this set on ebay, the guy wanted $5 for it. I don't want to get it if it is going to be ****, I will just order some spruce from LMII. the last guitar i built i used bearclaw and it came out awsome, but was trying to find a cheaper top.

I have a bunch of Sitka sets and billets. I cut all of them from hand split Sitka so I know the sets are cut with minimal runnout and such. If you want lower grade the factor that brings them down will be visual(which you can tell me what would be acceptable or not acceptable. There are different things that bring the grade down such as small pin knots that may have no real effect on structure(sometimes they are in areas that will be outside the pattern* but I have to degrade because I don't know what will be built with the set, sometimes it is color variance that has nothing at all to do with performance). All my Sitka is very nice old growth with pretty high ring counts(high grade or low grade), the grading is all visual. If you want sets to toy around with(experiments) I have those also. I get a big mix when I cut the raw split bolts, and if anything has a structural issue I just through it away(not worth wasting time with junk when I cut so many). Also, I can shoot you some raw split bracewood if you need. I usually don't sell bracewood, but I do have big piles of the stuff.

Shoot me a PM and let me know what you are wanting to build. Let me know what visual factors are most important, and what you can live with. Also let me know if you would like some extra bits for future projects, testing or whatever. It would be best to put enough in the box to make the shipping a good deal(one set and the minimum shipping cost will be silly expensive). I have other wood for acoustics also(back & side sets and what not) if your looking for anything like that let me know what your after. I will make you a VERY good deal, and I will make sure the wood is what you want.

Rich

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Growth rings. The number of rings and or size becomes a factor because early wood and late wood are very different in strength and density. Early wood is the lighter colored part of the rings. It grows fast with lots of moisture and is much less dense and strong compaired to late wood(dark rings). The overall ratio of late to early growh is really what is important. The more late wood the denser and stronger it will be. This is why many seek wood from that grows more slowely at high elevations where moisture is often frozen much of the year and less available to the tree for growth. You also should onsider ring spacing, as very wild swings from wide rings to skinny will give you wood with less balanced strength/stiffness across the board. Very large differences may lead to focused stress in areas instead of spreading it about the top more evenly.

Well I don't think that there's much anybody could add to Rich's post, but I'll have a crack anyway :D

People often refer to old and new growth wood in a different (but along the same lines) context. When I was looking into building snooker cues, they refer to old growth and new growth as essentially the difference between new and old trees. When making cues, you want really straight grain with the growth rings as close to each other as possible, this makes the cue more stable and the wood denser. Older trees are generally from natural woodland where the trees are closer together and there grow slower as there is only a finate amount of light and feed. Newer trees are aften "farmed" (for want of a better word) and are grown further apart (this could include thinning out of woodland) therefore the trees grow quicker and the rings are futher apart.

There's a lot of that in woodworking, where each branch has a slightly different lingo. Get's bloody confusing sometimes.

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