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First solar kiln load results7/15
I just recently finished drying the first load of 4/4 ash
The load is just shy of 400 bd/ft, and all 8 foot lengths,
The kiln is based on the Virginia Tech plans, with a
Following the guidelines in the Virginia Co-op Extension
I cut sample boards for monitoring MC rate of loss, and
The oven dry samples showed the ash coming off the
As per the VT documentation, I cut two 30 inch sample
The VT doc mentions quarter sawn lumber drying slower
Below are the readings/measurements I took each
I averaged the readings of the two sample boards
Day 1 12% | MC-33 vents 1/4 open
Some worthy-of-mentioning items ....
The last 4 days were as sunny and hot (touched
The first three days, moisture loss was very
Things seemed to stall when the MC got to
The last couple of days, I took additional
I decided to leave the lumber in the kiln for
I'm going to post some responses that include
Some pics of the kiln - the plan is to
I had a large piece of commercial rubber
I found an inexpensive ($40) temperature/humidity
The device has built in software that produces
I bought a second one to monitor outside
The recording device is:
Elitech GSP-6 Temperature and Humidity Data Logger Recorder
And can be purchased at Amazon:
I used three Lasko 20 inch fans, and made individual
After the roof is lowered/closed, the fan mounts
After running the first load, I have some
1 - The fast rate of loss (too fast) when the
2 - what type of degrade would one
3 - what would suggestions be for holding
It's worth noting that this first load was
1. I assume that you appreciate that the drying rate is based on the RH, velocity and temperature. With the vents open wide, plenty of air flow, and lots of sun, you will be able to dry the wood quite rapidly. Closing the vents a bit at the beginning, will slow down drying by raising the kiln humidity. The loss per day is the actual MC loss and not a percentage of that loss. So, 33% to 30% is a 3% loss and not 10% loss. So, you are not close to the maximum rate. The gain at the end might be because you are running the fans too much. Turn them On after the kiln has heated 10 F in the morning- -9AM ?- - and off around 7PM.
2. If you dry ash too fast, we might expect some minor cracking. You are not close to "too fast."
3. Cupping of wide pieces with the pith in or near is next to impossible. It is a natural event for wood. This cupping is a disadvantage of sawing "through and through" or live sawing. Slow drying encourages cupping.
Thanks Gene .... particularly the maximum
It's obvious from your explanation that I
"Slow drying encourages cupping."
Leads me to believe that it might be worth
All in all, it's been fun watching these first
Gene, why does slow drying cause more cupping? I am a novice wood dryer. I have bought a couple of batches of lumber green from a farmer with a woodmizer and have not had trouble with what I would consider over cupping. Most of it was maple or ash, and 10” or less wide. I air dried the wood outside in a well stickered stack for two years that was covered on top, but the sides where open to the elements. I thought the wood came out good for what I paid. It had very little internal stress.