Wood & Humidity, was Hammers [OT]

[Brian Lawson]

>From the slang I was brought up with it would be:  "Thick as a brick",
another term would be "as thick as two short planks" or "a right two by four
(2" x 4") "

Brian Lawson, RPT, MPT
Johannesburg, South Africa


> Hi Terry,
>
> Have you ever heard the expression "As thick as a plank" you may have to
> take this into consideration in your examinations of the explanations.
>
> Or is it "How thick is a Plank ?"
>
>
> Tony Caught ICPTG
> Australia
> caute@optusnet.com.au
>
>
> > Well, I don't dispute your facts. The most pertinant thing here is
likely
> > the following:
> >
> > > "End grain absorbs fastest, on the other hand and which
> > > abounds in actions but not so much in boards."
> >
> > It's easy for me to imaging uncoated endgrain action parts absorbing
> > moisture much more quickly than coated soundboard cut parallel to the
long
> > dimension.
> >
> > Terry Farrell
> > Piano Tuning & Service
> > Tampa, Florida
> > mfarrel2@tampabay.rr.com
> >
> > ----- Original Message -----
> > From: "Clark" <caccola@net1plus.com>
> > To: <pianotech@ptg.org>
> > Sent: Monday, January 01, 2001 12:33 PM
> > Subject: Re: Wood & Humidity, was Hammers
> >
> >
> > > Hi there, Terry,
> > >
> > > > Are we really sure that a varnish/laquer covered spruce panel
> > > > would absorb more moisture than an unprotected piece of
> > > > maple/hornbeam/walnut (or whateverelse and action is made of)?
> > >
> > > My tattered copy of the "Wood Handbook" (Department of Agriculture,
> > > 1955, and it came that way) gives moisture shrinkage ratios for a ton
of
> > > stuff (more than their current pub's, maybe less than "Woods of the
> > > World") but not the times involved. (Do drying schedules reflect this?
I
> > > don't have a reference as to their meanings.)
> > >
> > > Wood 20%wmc 6% 0%
> > > Spruce 3.8 8.0 11.5
> > > Maple 5 11.9 14.9
> > > Hornbeam 6.5 13.6 19.4
> > >
> > > (p.315-318)
> > >
> > > So far as finishes excluding moisture at 11%wmc over two weeks of
nearly
> > > saturated conditions, the following table is given:
> > >
> > > 3 coats of Al powder in gloss oil/varnish 92%
> > > 3 coats Al powder in shellac 92%
> > > Heavy coating of paraffin 91%
> > > 3 coats rubbing varnish 89%
> > > 3 coats shellac*********************************87%
> > > 3 coats enamel (cellulose-lacquer vehicle) 76%
> > > 3 coats cellulose-lacquer 73%
> > > 3 coats gloss oil bronzing liquid 12%
> > > 3 coats furniture wax 8%
> > > no coats of anything 0%
> > >
> > > (p.377)
> > >
> > > Extrapolating from this in terms of volumetric expansion ratios, for
an
> > > arbitrary 1x1x1 square at 11%wmc over an exposure period, either
raising
> > > or lowering wmc by 2%:
> > >
> > > wood 11% +2% -2%
> > > Spruce 1 1.001 0.999 (shellacked)
> > > Spruce 1 1.008 0.992 (unshellacked)
> > > Maple 1 1.010 0.990
> > > Hornbeam 1 1.013 0.987
> > >
> > > Most probably it's not so linear or uniform, and surely these average
> > > values neglect differing absorption rates due grain orientation:
radial
> > > (quarter) and tangential (flat) absorption is compared for Douglas Fir
> > > and SY Pine. Assuming the figures I used above are for an equal
> > > distribution of grain orientation, the overwhelmingly radial board
> > > should change dimensions more than more or less square action parts.
End
> > > grain absorbs fastest, on the other hand and which abounds in actions
> > > but not so much in boards. Else that old stuff is as differr/9uas I've
> > > heard claimed!
> > >
> > > Does this stuff look right?
> > >
> > >
> > > Clark
> > >
> >
>