Wood & Humidity, was Hammers

[Farrell]

>" Both spruce and pine are both soft timbers, cut on the quarter which
> promotes swelling of the soundboard.  The soft timbers will of course
accept
> moisture more rapidly than had woods."

I don't think the above statement is necessarily true at all. Both spruce
and pine are "softwoods". All spruce and some pine woods are soft. Some pine
woods are extremely hard. Some "hardwoods" are soft and some are hard. A
"softwood" cut at a time when much resin is present in the wood may make the
wood less susceptible the water content gain from high humidity. "Hardwoods"
can vary to extremes on their ability to pick up moisture from the air -
largely based on their cell structure. Trees have interconnected cells that
allow water movement from the roots to the leaves. These cell can large or
small diameters. Also, upon a cell's death, the cell ends may close or open
up. A species group such as red oak (certainly a very hard "hardwood") has
both large interconnected cells and the cell ends are not present after cell
death. Cut a six-inch long piece of red oak. Put your mouth up to one end
and blow. You can feel the air coming out the other end (or dip one end in
water and you can make bubbles!). Certainly these kinds of structures open
up such a wood to rapid changes in moisture content. The white oak group on
the other hand has little end caps on each of the same cells, thus
preventing water from flowing through the wood. That is why they make oak
wine and whisky barrels out of white oak - because liquids will not pass
through. These are some of the properties that give white oak many uses in
boatbuilding and make red oak a big No No in virtually any boatbuilding
application.

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com

----- Original Message -----
From: "Tony Caught" <caute@optusnet.com.au>
To: <pianotech@ptg.org>
Sent: Saturday, December 30, 2000 12:32 AM
Subject: Re: Hammers


> So OK, I neglected to say that the pianos also go out of tune whilst I am
> tuning it. And that under these circumstances it is virtually impossible
to
> tune a piano properly.
>
> Both spruce and pine are both soft timbers, cut on the quarter which
> promotes swelling of the soundboard.  The soft timbers will of course
accept
> moisture more rapidly than had woods.
>
> Have a photo that I will send (when I get a scanner) of a Yamaha bridge
that
> opened up on a glue joint you would love to see. (Yamaha replaced the
piano)
> The piano was 8 years old.
>
> If you look at the bridge joints in Yamahas you will notice that in most
> cases the glue joint is very dark, waterproof glue. As against the lighter
> colour joints in their non tropical pianos that are not waterproof.
>
> Regards
>
> Tony Caught ICPTG
> Australia
> caute@optusnet.com.au
> ----- Original Message -----
> From: Newton Hunt <nhunt@jagat.com>
> To: <pianotech@ptg.org>
> Sent: Saturday, December 30, 2000 12:34 AM
> Subject: Re: Hammers
>
>
> > > Now peoples, please don't tell me that the wood (maple or birch or
> > > whatever) absorbs moisture that fast.
> >
> > Ok, I won't tell you, but I have had concert instruments go
> > out faster than I can tune them when the load in door is
> > opened.  Very frustrating but you do what you can.  Spruce
> > absorbs moisture in five minutes or less.
> > --
> > Newton Hunt
> > Highland Park, NJ
> > mailto:nhunt@jagat.com
>
>