Wood & Humidity, was Hammers

[Tony Caught]

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
> >
>