Nicholas,
The wood you describe sounds a lot like the recent (2-3 years) sheet
stock I've seen for "Very Light" (4# - 6#) from Sig (Solarbo). It's
pretty bad generally with bowed plain-sawn grain (compression/tension
wood), mostly well over 6#, and all the light sheets are checked. I
picked up a couple of the more decent pieces because the shop owner
made a special effort to stock it for my convenience. Strips were
twisted, and bowed badly. Restock material has only gotten worse since
sheets are bundled as cut from individual planks.
The "checks" I see aren't generally visible until the face of the sheet
is positioned at an angle to light; flourescent light in my work area
and most commercial light. They are much easier to see in "c" and
quarter grain faces and far more common in lighter density wood. These
checks show up as very fine, white, lint-like lines crossing the grain;
much like fiber filaments in carpet thread.
If you can work around them, cut out and throw away the checked
sections. A strip will always break at these checks, or I missed one.
Usually, I try to keep the integrity of the shop sheet so will mark the
checks with a highlighter pen. It's best to pass over these sheets at
the shop bin, but I'm a repeat customer and often leave with a lighter
wallet and the bad sheet. They usually are very attractive
superficially.
The plank my stiffest wood is from has both one of these cracks I'm
aware of and a "dimple" which may be where the tree bent and the grain
was crushed; much like bending a strip which kinks from too much grain
compression. I've gotten into the habit of testing spar wood from a new
sheet by sacrificing two or three strips to identify any localized weak
points. I find it extremely hard to see checks in a and b grain, thus
the sacrifice.
I'm not convinced that the checks are a result of wind damage, felling
trauma, or my own ambitious buckling tests. I feel they are a result of
improper drying and lighter densities are more prone to checking as the
log, or billet, shrinks. This is a common consideration in any
commercial wood drying process. Tim G. would see this more, but I had
one billet with a yard cut severely checked on the surface and decent
wood about 1 inch into the plank. Nature tends to heal itself and any
natural injury would have evidence of repair. I don't see this in any
checked wood I have.
The darker cracks Don described sound like actual cracks created during
felling or in live wood. I don't see these very much, but they are
pretty visible due to mineral deposition.
Good building,
Bruce in Seattle
--- In Indoor_Construction_at_yahoogroups.com, "Nicholas D. Huang"
<ndhuang_at_v...> wrote:
>
> I have a sheet of 1/32" balsa that is behaving very oddly. I
stripped
> off a piece and it immediately splintered into 1-2 inch fragments.
With
> a little magnification, you can see a very weird grain pattern that
runs
> at a slight angle to the sheet. Where this crosses the edge of the
> sheet it breaks. The wood is also an odd color- it's almost gray, as
if
> it had weathered. My question is, what can I do with it?
> Nicholas Huang, Boise, ID
>
Received on Sat Jan 21 2006 - 09:03:50 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET