Drying thick pecan in Nyle L200

KenMac · June 19, 2021, 04:24:12 PM

Just to update my saga of pecan slabs in my kiln: I have monitored kiln temp and RH since January and as outside temp has risen so has kiln chamber temp. As of this morning temp was 96.8 and RH was 82.4. RH is consistently dropping .1 to .2% a day. The slabs and 4x4's show no sign of degrade at this point and stack has shrunken in height by over an inch. I do not know MC of wood at this point, but am going as slowly as possible. I'm thinking that soon I will turn compressor on for about 5% of the time and try to move the process along. I am going to try to get an MC but am uncertain if it will be realistic. My Electrophysics moisture meter claims to read up to 99%, but I doubt its' accuracy. We'll see how this goes. Thanks again for all of the advice and please keep it coming when you think I should do differently than my plan.

customsawyer · June 20, 2021, 11:43:02 AM

I would recommend a Delmhurst J2000 moisture meter. Need to know what your moisture is to be able to give the best advice.

KenMac · June 20, 2021, 08:02:09 PM

Quote from: customsawyer on June 20, 2021, 11:43:02 AM
I would recommend a Delmhurst J2000 moisture meter. Need to know what your moisture is to be able to give the best advice.

I have the Delmhorst J2000 but it only reads to 36 or so percent I think. Even if the Electrophysics (which I bought from Nyle with the kiln) is inaccurate I thought it would possibly show a rate of decrease in MC. That was my thinking anyway. Thanks for your input.

KenMac · June 25, 2021, 08:30:40 PM

Even though I figured I'd be wasting my time, this morning I checked the pecan slabs and 4x4's with the Delmhorst J2000 meter. To my surprise with the hammer pins driven in completely it showed the slabs to be in the 19% range and the 4x4's at 22.2 to 23.6%. There has been no heat or compressor running since the first week the kiln was loaded. I can see no cracking or degrade on any piece. Granted I can only check exposed areas but I never imagined MC would be this low. Temp is 97 and RH is 81.6%. I'm thinking I should let it ride as is for a while longer even though I'm tempted to run compressor at 5%. Anyone have a suggestion on what to do now? Thanks in advance for your input.

WDH · June 26, 2021, 07:04:50 AM

I would run the compressor some. Likely the core moisture is higher but you could ramp the drying up one notch.

customsawyer · June 26, 2021, 07:12:49 AM

Also check your moisture meter and make sure you have it set for insulated pins when using the hammer.

KenMac · June 26, 2021, 05:44:10 PM

Quote from: customsawyer on June 26, 2021, 07:12:49 AM
Also check your moisture meter and make sure you have it set for insulated pins when using the hammer.

Thank you. I will check that and recheck Monday.

KenMac · June 28, 2021, 05:43:19 PM

Well, I have determined that either I am not blessed with the Delmhorst smart gene or the J2000 is not intuitive or user friendly. To the best of my ability I set the meter for insulated pins and checked several slabs and 4x4's. MC ran from 22.3 to 23.6. I am still surprised at this but I guess it is true. My plan is to start compressor at 5% for a while and monitor unless you kiln guru's advise otherwise.

customsawyer · June 30, 2021, 05:22:12 AM

What part of the slabs are you sticking the meter? How deep are you driving the pins?

KenMac · June 30, 2021, 07:09:21 PM

Quote from: customsawyer on June 30, 2021, 05:22:12 AM
What part of the slabs are you sticking the meter? How deep are you driving the pins?

I'm checking exposed areas on the surface obviously near the edges. Some are on the air inlet side and some on the outlet side. Pins are driven in as far as possible- to the connector. Thanks for responding. Checked a second time and readings were very similar with one slightly higher and the rest slightly lower- maybe 0.2 either way.

customsawyer · July 01, 2021, 06:04:35 AM

When drying slabs I like to have a couple of a places where a narrow slab is above a wider one. This lets me check closer to the core in the face of the slab. I find that the edges and ends dry faster than the core. Try to have your probes in heart wood as it will normally read higher than sap wood. Also be careful driving the pins in all the way. Your meter might be reading the surface moisture if the face is making contact with the lumber. I only go in about half the thickness of the slab.

KenMac · July 01, 2021, 08:13:39 PM

Thanks Jake. I will alter my process and keep checking. Is the Relative Humidity reading reliable in telling MC at this point or is that only applicable after drying is pretty much complete?

WDH · July 03, 2021, 10:57:25 AM

It tells you the drying force on the outside of the slab, not what is inside.

KenMac · July 03, 2021, 02:07:47 PM

Quote from: WDH on July 03, 2021, 10:57:25 AM
It tells you the drying force on the outside of the slab, not what is inside.

Thank you Mr. Hamsley. I'm slowly learning this stuff, but will probably never get proficient at drying or sawing. :-[

WDH · July 03, 2021, 05:48:51 PM

Doing is how we learn best.

Stephen1 · July 04, 2021, 06:01:00 PM

Quote from: WDH on July 03, 2021, 05:48:51 PM
Doing is how we learn best.

And reading these post on FF

WDH · July 05, 2021, 07:34:39 AM

A fantastic resource to counter the School of Hard Knocks.

KenMac · July 05, 2021, 02:41:33 PM

Quote from: Stephen1 on July 04, 2021, 06:01:00 PM
Quote from: WDH on July 03, 2021, 05:48:51 PM
Doing is how we learn best.
And reading these post on FF

This one of the main reasons for me posting this thread. There is some extraordinary wisdom here!

K-Guy · July 06, 2021, 08:36:40 AM

Quote from: WDH on July 05, 2021, 07:34:39 AMA fantastic resource to counter the School of Hard Knocks.

I'd like to know when I can get out of that school!! :D

KenMac · July 06, 2021, 06:38:47 PM

Quote from: K-Guy on July 06, 2021, 08:36:40 AM
Quote from: WDH on July 05, 2021, 07:34:39 AMA fantastic resource to counter the School of Hard Knocks.

I'd like to know when I can get out of that school!! :D

I don't think they give diplomas or even have a graduation service! The knocks just get harder.

KenMac · July 14, 2021, 05:26:10 PM

Update on pecan slabs: MC today ranged from 13.5 to 17.8 % still with no visible degrade. Kiln temp was 99.8 and RH was 74.5%. RH has been dropping about 0.5 to 1% per day for the last week or so. MC has dropped about 0.2 to 0.4% per day. I decided to turn compressor on at 5% and kiln temp at 105. I'll monitor and report back in a few days. This endeavor may actually turn out successfully after all and not take as long to complete as thought or feared. We'll see. Thanks again for all input and direction to get this far along.

KenMac · August 19, 2021, 04:44:30 PM

Time for another update on my adventure drying thick pecan slabs and 4x4's: Moisture content as of yesterday morning ranged from 6.0 to 9.3% with no splits or visible degrade. Kiln temp was 123 degrees. I decided to start sterilization process and turned heat and heat lamps on with setpoint of 150 degrees. Setpoint was reached by noon. This morning temp was at 156 on Nyle controller and 150 on my Elitech monitor with RH at 28.3% in kiln. Since slabs are 3" thick and 4x4's are obviously thicker I plan to leave temp up like this until Saturday unless advised otherwise. I will check the load tomorrow for changes but I hope all is well.
Thanks again to all who have taken interest in this project and offered advice and support.

YellowHammer · August 19, 2021, 05:01:09 PM

During the sterilization process keep the auto vents closed and try to control the temps by playing with the heat lamps.

Try to keep whatever hot moist air in the kiln to stay in the kiln. This will mostly stop drying the case and allow the core to equalize to the case. It will bring the moisture gradients closer.

KenMac · August 20, 2021, 09:21:02 PM

Thanks YH. Will do and so far, so good. How long should I leave the kiln closed after turning the heat off after sterilization is complete to allow equalization of core and surface?

YellowHammer · August 20, 2021, 10:59:06 PM

I'll typically turn everything off, including the fans, because they build up pressure and may evacuate more moisture which is not desired, and let things sit for 24 hours. Just flip the switches and walk away for a day. Just a nice, gradual cool down, and then probe again to check for case and core spread and also average MC. The 3.3 % spread you are seeing is pretty high, your average moisture may settle to 8% maybe 7%, which would put you in target. If the case to core values haven't tightened up, go through the reheat cycle with the vents closed again.

Differential moisture content causes wood movement as the values equalize, so it's best to try to get them in alignment now instead of after they have been planed or flattened.