Wood Drying

[Ron Overs]

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>Terry,
>
>Your most immediate danger is too rapid drying through the end grain.  THe
>dimensioinal change from differential drying through the end can create
>checking that will make large sections of wood unusable.  Don't waste a
>second getting some form of moisture-impervious sealant into the end of
>every piece.  Melted parafin wax works best, IMHO.

Or, if you have any wood glue (out of date Titebond or rubbish PVA) 
lying about, that works very well also. When sourcing local logs, we 
specify that the log is end-sealed as soon as it is cut.

Your idea of breaking the log down into 1/2" boards is a good one. 
Such boards will be ready to use in one year with just air drying 
(ie. for the panel, rib stock will take at least two years, unless 
you plan to make laminated ribs out of the 1/2" boards). When we 
break down a log for sound board material, after the large boards (2" 
thick) have been cut out, we break down all the small triangular 
flitchs into 1/2" wide boards, so as to obtain the maximum of useable 
spruce from the log (you will need a resaw with a tilting table for 
this purpose). The danger with drying is moisture gradients. 
Therefore, the thinner cut boards will tend to have less of a 
gradient problem, but they will be more prone to warpage. As soon as 
you have cut your boards, they should be stacked with spacing sticks 
(of say 25 mm by 25 mm section) between each layer of boards, spaced 
at about 300 mm (1') for boards 1" or thicker. I would recommend that 
the spacing sticks be set somewhat closer together for 1/2" boards to 
reduce warpage. The entire stack should be covered with some kind of 
roofing material and weighted on top (house bricks will do) to ensure 
that the upper boards in the stack are held down to prevent them from 
warping. Don't make the stack too high or the overall weight will 
cause the lower boards to sustain crush damage adjacent to the spacer 
sticks.

I'll photograph the drying stack I have at the house and send you a 
jpeg. Looking at your location Terry (27 degress N, - I notice that 
you have another Sydney a few miles east), I would recommend that you 
commence the drying process during the winter months, since the 
summer heat will be very risky for freshly sawn boards. It is the 
initial drying phase during which degrade from moisture gradients is 
more likely to occur. Furthermore, quarter cut boards will tend to 
lose moisture faster through the edge of the board compared to the 
quartered face. This will occur with a quarter cut board since the 
medullary rays will be perpendicular to the edge and parallel to the 
board face. We seal the edges of quarter cut boards as soon as they 
come off the saw. This will greatly reduce the risk of stress damage 
at the edge of a quarter cut board during the drying process. I have 
noticed a tendency for belly wood to be more prone to compression set 
damage adjacent to the board joints. While there may be a multitude 
of reasons why this might be so, I have long suspected that the 
tendency for quarter cut boards to lose moisture faster through the 
edge, particularly during the initial drying phase, to be a factor 
here.

By the way folks, our new sound board conditioning box is coming 
along nicely (the new box is big enough to accommodate a B=F6sendorfer 
Imperial board). If anyone is interested I'll be taking a photo of 
the assembly prior to fixing the last side of the box, so that you 
can view the layout of the air ducting. I'll put in on the web site 
and let you know when it is up.

Best,
Ron O.
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OVERS PIANOS - SYDNEY
Grand Piano Manufacturers

Web: http://overspianos.com.au
mailto:info@overspianos.com.au
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