Where did the RH Go

[Ron Nossaman]

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>I'm not an expert in that area really. I can say that there in all capital
>cities in Canada humidity at some point in the year does exceed 60%.
>
> >Don,
> >Does that mean that if rust is present, that RH levels have at one time=
 or
> >another exceded 60 %?


Hi Don, Owen,
I don't think it's an absolute humidity level thing. Any time the strings=20
(etc) are colder than the dew point of the surrounding air, you'll get=20
condensation on the strings and rust.

Go here and play with this some.
http://www.srh.noaa.gov/elp/wxcalc/rh.shtml

According to this, bringing a piano into a 70=B0 F room at 40% RH from a 40=
=B0=20
F truck will do the trick. Un-heated storage facilities, or inadequately=20
heated rooms that are heated and filled with folks exhaling hosannas for an=
=20
hour or so once a week might well do the trick too.

It's cumulative as well. A little here, a little there, and eventually,=20
you're talking serious rust.

This site also, incidentally, has the newest and bestest state of the art=20
psychrometric calculator available to calculate RH% from wet bulb, dry=20
bulb, and atmospheric pressure, near as I can ascertain.

Ron N

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