I've been sawing and drying thousands of feet of
ash over the last couple of years, and have gotten
very familiar with its behavior in my solar kiln.
Even at this time of year (late June), when the
kiln performs at its best, I haven't had any issues
with a "too fast" drying rate. My typical loads are
500-600 ft of 8-10 foot lengths of 4/4 lumber.

In this next batch, I have a cherry tree that was
uprooted in a storm a few weeks ago that I'd like
to include, and recognize that the max drying rate
for cherry is much much slower then ash. Ash is listed
at 10-1/2% per day while cherry is just under 6%.

I have some thoughts on how to approach this, and
would appreciate input/suggestions ....

1) cover about half of the kiln roof to slow the
drying rate. Covering the roof will be a bit of a
pain, but I'm just wondering if the two approaches
below have merit - they'd certainly be easier.

2) reduce fan speed - I use three, 3 speed fans
and typically run them all at the fastest setting.
I could run them at the lowest speed .... this would
certainly be the easiest approach.

3) put the cherry on the bottom of the stack and
partially block the horizontal sticker gaps to
slow the airflow only around the cherry. This would
allow the rest of the load to dry at the normal rate
while slowing down just the cherry.

Some additional questions .....

Q1) In a normal load, if cherry and ash were mixed,
would monitoring the drying rate for ash
samples provide current info on the rate
of loss for the cherry? In other words,
with kiln conditions the same for both, would
they loss moisture at the same rate?

Q2) in any of the methods, does damage from a
too-fast rate start immediately, or is there
any kind of grace period? How would one day at a
too-fast rate compare to 2, 4, 6 days? I can
monitor the rate daily

Q3) is there a MC point where the drying rate for
cherry can be accelerated without risk? I've
read over the years that once MC reaches mid/low
20's, potential drying problems are greatly
reduced ... maybe even gone?

I hope to use this round of drying as to hopefully
come up with the best way to dry mixed species in
a load. I don't saw at any volume, and can see
that there could be instances in the future where
mixed loads would be an advantage. Any thoughts
on the over all aspect of drying mixed species
is appreciated

Carl

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The sheets alone are not useful as a vapor barrier, as moisture can get around the edges. Special sealing is required for the edges when two panels join or the panel is in contact with wood framing.