Have been reading the forums for many years now. Thought I will contribute. I am starting with a long thread so excuse me. I have always wondered about the explanation for following statements that people often make about willow:
#1: More/tighter the grains better the ping
#2: More/tighter the grains lesser the life
#3: Bat with more number grains or tighter grains opens quicker than one with lesser number of grains
#4: Knocking-in opens up the bat
So I did some research and here is the gist. Please let me know if it makes any sense. Still some questions need answers:
The cross section of a willow bat/cleft/tree reveals a series of parallel straws (
http://www.psmicrographs.co.uk/corkscrew-willow-xylem--sem-/science-image/80201781). This seems to be unique in willow among other tree's. The moisture content can escape very quickly due to these open ends when cut hence the need to wax/varnish the ends as the cleft is cut. At the same time, if left on a wet surface moisture can rise up into the toe and beyond rapidly through capillary action. This explains why the toe swells up sometimes. In pressing one aims to harden a thin layer of the face by compression and this in essence flattens the straws and allows them to flex into the soft middle which upon return to shape gives the rebound. More the natural moisture trapped in the straws, more the surface will rebound. Low density willow means that the straws are wider in diameter tapping more moisture.
Now about grains (copied from
http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/1_Wood_Grain/1_Wood_Grain.htm): At the very center is the pith. In some trees, this is much softer and possibly a different color than the surrounding heartwood. Heartwood is made up of dead cells that no longer serve any purpose except to support the tree. Next is the sapwood, which carries water, minerals, and plant sugars between the roots and the leaves. This is often lighter in color than the heartwood. Outside the sapwood, close to the surface, is the cambium, a thin layer of living cells. These cells manufacture the wood as they grow. The cambium is covered by a protective layer of bark. The cambium grows rapidly at the beginning of each growing season, creating light colored springwood. As the climate warms, it slows down and produces darker summerwood. This later growth is somewhat denser and harder than the early springwood. As the weather turns cold, the cambium becomes dormant until the next spring. This cycle produces distinctive growth rings.
The darker color of the grain, which is also the harder part, runs perpendicular to the face of the bat. I would imagine that tighter grains would result in a overall harder surface that will be harder to flex inwards. So how does having tighter grains result in a more "pingy" bat? Some say that the harder surface has a better transfer of energy to the ball and lesser vibrations. So by that standard, we should press our bats more. I am not quite sure how the life of the bat is related. Some say that tighter grain bat is older wood, which makes sense. But I am not sure why older wood would break easier if it harder. Does it make the bat more brittle?
The process of knocking knits the surface fibers together forming the thin layer at the top. This layer flexes and rebounds upon impact and the inner straws go through temporary compression and decompression. I believe knocking helps in making the inner straw like structures loosen so they can compress easier and then decompress back to their original shape hence providing better rebound.
Not sure if all this makes sense. It would be good to get some discussion going.
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Topic: Willow ping and grains: does this make sense? (Read 24512 times)