Seems the only way to save my tree ring is to soak it in peg. 36"
for a large vat. Question. Can a plastic container be used with peg,
or will it be
People report both ways on finishing a piece of wood preserved in this
it will and will not take a finish. I want to get a clear finish on it.
Will I be able to?
I use plastic. In your circumstance, you could certainly enclose in a large
plastic bag, add solution, use a straw to extract excess air.
PEG is a slimy, waxlike substance which will leave your piece darker,
deliquescent, and almost completely resistant to any finish. Are you SURE
this is what you're after?
Deliquescence describes the property of dissolving through the
absorption of moisture in the air. Some chemicals exhibit this property
(I think anhydrous NaOH might be one.) Polyethylene glycol is one, as
well (I just checked.)
Since his workpiece will not lose form, but will absorb moisture, it
would suffice to say it's going to be wet. You might get away with
A big ring is usually stabilized by putting an
iron band around it. You could adopt that
principle, or you could simply let it split.
Plastic should work fine to contain the PEG. I
have never used PEG, but have a book "Woodworking
Factbook" by Donald G. Coleman, 1966 which
describes the process of finishing with
polyurethane. This is fairly old but he said
polyurethane was the only finish know to dry
properly on PEG treated wood.
On Tue, 17 Jan 2006 02:34:33 GMT, "George E. Cawthon"
Given that the thing is already doing its best to shrink anyway, what
use is compressing it going to have?
Disks don't crack because they shrink, they crack because because
tangential shrinkage is bigger than radial shrinkage (as has been posted
in great detail many times before). The outer rings no longer fit around
the inner rings. Avoiding cracking thus needs to either stop shrinkage
(PEG), to remove the centre and allow the rings to collapse in on
themselves (bowls), to allow the rings to stretch (halving) or possibly
to crush the centre of the log to a smaller diameter (small disks, or
stored energy for later sudden splits).
If you could invent an iron ring that compresses the centre
preferentially to the outside, then it might work.
You're right so far, but you're missing something. When you compress
the disk, you compress all the layers radially -- that is, you add
radial shrinkage without adding more tangential shrinkage. This brings
things back in proportion, thereby stopping the cracking.
An alternate way of thinking about it is that you're moving the outer
rings in, by squeezing things. Thus, they end up in a circle with a
smaller circumference, and thus they don't need to crack in order to
fit. There's no need to "invent an iron ring that compresses the centre
preferentially to the outside", as you suggest, because compressing the
outside doesn't hurt anything.
The "bmoses-nospam" address is valid; no unmunging needed.
I would say let it crack, as that is what it will do eventually. You
can try soaks in liquid dishwashing detergent denatured alcohol,
(research on rec woodturning), and then drying. These methods will not
cause problems with finishes. Steaming and boiling can also be done,
but I haven't tried either yet. You could try some sort of huge band
clamp around the slab, and that might work. Wood moves, and rounds will
NB - neither method "works" at all.
the unbroken circle, while contracting, will find a weak spot to create some
space. Banding would do nothing, since it stresses in the direction the wood
wants to go anyway.
Cutting a single kerf from outside to center would be my choice. Low angle
plane will reveal the growth rings. You can always Nakashima it if you
decide to use it as a display.
Don't take anything out, it'll find comfort along the place you relieved the
Layer either side with double layer newsprint, change one a day for a week,
once a week for a month, and once a month until the whole thing stops losing
I'd suggest googling (or asking) over at rec.woodturning. Bowls are
often turned "green" and placed in a plastic bag. The bag is then opened
occasionally for a while to let out the moisture, and resealed. Thus slowing
down the drying process. It would seem your situation is similiar to
seasoning a giant turning.
This has worked well for my small turnings, but someone at the other
group might know more about how to handle a large piece better. --dave
Doesn't work for disks. Bowls survive because the "rings" are
effectively hollow and they can collapse inwards. There's some warping,
which is why you only rough turn them thickly when green, then finish
turn once dry after they've finished warping.
I'd make a couple of disks (or more, if I had them) then put a radial
sawcut into the centre. This puts all the "crack" into one place, rather
than allowing them to occur randomly, and probably multiply. When
they're dry, pick the best matching pair, convert them to opposed
half-disks and stick them together.
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