<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2802" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>There was a discussion (s) a while back asking at
what rate does a soundboard loose/gain moisture. Related, I think the was also a
discussion about how long does it take to dry a panel down for ribbing. The have
also been discussions about how to determine whether a soundboard panel has
reached equilibrium moisture content (EMC).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I ribbed a soundboard panel today for a Steinway M.
The soundboard was partially redesigned by Del Fandrich. I built the panel and
laminated/radiused ribs. Below are data documenting the panel drying
process from shop conditions in which the panel wood had equilibrated with
for the past couple years (on 3/31 - just prior to putting the panel in the hot
box), through the drying process over a week, and ribbing which - well actually,
I'm in the middle of it - six of ten ribs have been glued to the
panel.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>
<TABLE borderColor=#000000 cellSpacing=1 width=384 border=1>
<TBODY>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Date</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Temp</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>RH</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>EMC</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Width</FONT></P></TD>
<TD width="17%" height=16>
<P></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>03/31</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>70</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>50</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>9.2</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1136.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Shop</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/01</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>98</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>33</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.4</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1135.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/01</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>100</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>25</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>5.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1134.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/02</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>83</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>30</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.4</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/03</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>83</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>33</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.4</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1134.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/04</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>87</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>31</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.4</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/05</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>85</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>30</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.0</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.3</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/06</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>85</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>31</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.2</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.2</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>04/07</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>86</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>29</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>5.9</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.2</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Hot Box</FONT></P></TD></TR>
<TR>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Rib</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>70</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>35</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>6.9</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=center>1133.2</FONT></P></TD>
<TD width="17%" height=16><FONT face=Arial size=2>
<P align=right>Shop</FONT></P></TD></TR></TBODY></TABLE></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>I determine whether the panel has reached EMC by
measuring across the grain at the widest area of the panel. The width units are
millimeters. As you can see, the panel shrunk 2.8 mm while its MC dropped from
9.2% to 6.0%. I use a good quality tape to measure and I am estimating the
tenths of millimeters. You can also see that after about two days in the hot
box, the panel had shrunk down to 1133.4 mm - almost consistent with a 6.0% EMC
- the hot box conditions got away from me a tiny bit and RH went up the
next day and thus EMC, but quickly went back down with a little more heat. You
can also see how the panel shrinks with lower EMC conditions, and also grows
with increasing EMC conditions (4/2 to 4/3).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>When you raise the EMC conditions in the hot box
and observe that the panel increases in width a bit, you know the panel
previously was at a lower MC than the new EMC - so you can be very sure the
panel had equilibrated with an EMC lower than your new EMC.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I normally keep my shop between 45% and 50% RH, but
when I rib, I crank up the AC and the dehumidifier - as you can see, I have the
shop at 35% right now - I can spend quite a few hours ribbing a soundboard and
not worry about the panel picking up any significant moisture.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>BTW, I use a good quality certified hygrometer that
is documented to be accurate to within 0.2% RH.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Anyway, gotta go glue. Just thought some might be
interested.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Terry Farrell</FONT></DIV>
<DIV><FONT face=Arial size=2>Farrell Piano</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><A
href="http://www.farrellpiano.com">www.farrellpiano.com</A></FONT></DIV></BODY></HTML>