Expeditided Wood drying / Solar Kiln

[RobertNH]

It gets real a lot slower as it gets drier.

Are those LB/OZ/Fraction of an OZ?

If your scale does grams I suggest you do so, its a little easier to interpret.

I'll do a screen print next time.
LB / OZ Total ounces

I agree with the statement.
I figure it dries on a curve, not linear.
The goal is a .5% average.
From what I've read, seems reasonable.

Control pile reads 30% (resistance of .15, chart doesn't go that far)
Logs tested are at 22% (they've been in there 7 days).
MC test is now done with DMM and compensation of temperature.

 

[heatwise]

I like all 3, my reserve stack is like the first you show . It's up off the ground about 18" and it's also like your #2 with the plastic open at the ends. It's great to see the # 3 kiln.i think It's important to keep the plastic away from the wood so condensation formed can either roll down or evaporate away. I have a tent for winter camping that has 2 small roof vents to allow moisture to escape, this tent was one of my best purchases and reading the manual for it taught me about moisture build up . So applying the venting at the top was because of the tent info and also because the stack is between 2 posts and couldn't be completely covered.

 

[RobertNH]

Just finished up my weekend readings.
The Big Black Box is averaging 25%
The S&G Stack is running 25% (high in the stack) to 32% (low in the stack
I have now weighed control pieces in both of these, so better numbers coming next week.

Two weeks into the BBB & the S&G
One week with the Display Case

 

[RobertNH]

Thank you Heatwise for joining in!
I saw what you did on the other thread and have been curious how it worked out.

The open cover (now pinned to the ground on the front) has reached highs of 130F plus along the top (typical is 115F +-), but ambient temperature at the open back.
Surprised how well it's doing!
Just too simple a concept not to try!

 

[RobertNH]

It's going to be a tough week for drying..
Forecast shows mostly damp weather all week..
Figure I have 54hrs of good drying this week..
30 odd percent..

Question becomes to add the fan to the Display Case (solar kiln)?
Hurt or help?

My assumption, at this point in time, is the surfaces are drying nicely and probably some intermediate areas, due to the splits and cracks I see.
Interior I will not know until I reach a point of what I consider 'done' and split it and test.

I'm thinking to add the fan and create air movement.
I have a low speed fan (change air 6 times in 24hrs) I'm about to add..

Opinions??

 

[barnuba]

Great ideas here! Do you have the S&G stack in full sun all day or at least 80% of the day? This is what I attribute to making my kiln work.

 

[RobertNH]

Great ideas here! Do you have the S&G stack in full sun all day or at least 80% of the day? This is what I attribute to making my kiln work.

Both the S&G and the Display Case are at least 80% sun
The Big Black Box is 70%

Care to post up a pic of your Kiln?
Would love to see it!

So, let me ask, since you have on running:
Are you fan run?
Are your Solar heated?
How big did you go?
And would love to hear the results your getting!

 

[RobertNH]

This is what I hoped for.. Questions that tell me what else I need to put into the equations.
You guys are testing me on my test... I'm loving it!

Great Sun day today.. finally..
Tomorrow is recording day and with all the dank, dark days this week, this should be interesting.

 

[Silenced38]

Here what im thinking of tring. I built this as a green house. It scavenged sliding glas doors. I should be able to put a 1/3 cord in it.

 

[paul bunion]

This is what I hoped for.. Questions that tell me what else I need to put into the equations.
You guys are testing me on my test... I'm loving it!

Great Sun day today.. finally..
Tomorrow is recording day and with all the dank, dark days this week, this should be interesting.

I'll make a prediction. I will assume your weather was like it was here in the very north of NJ. I'm only 20 miles or so from CT.

If you are weighing in grams you will probably find that your pieces are a couple grams lighter right now. Their surface became very dry today so they will easily soak up some humidity tonight. They will be about 10-15 grams heavier tomorrow with their nightly followed by a rainy day with no drying and probably some more uptake. Weighing in Oz you might see no difference. If your wood was still very green you will measure some drying progress. The uncovered pieces will be 2-500 grams (up to a pound) heavier if it rains. That will depend on species and their size.

 

[RobertNH]

View attachment 140188 Here what im thinking of tring. I built this as a green house. It scavenged sliding glas doors. I should be able to put a 1/3 cord in it.

That's awesome!
The design is in line with the Virginian design I've read about.
Plus, is the extra space up front.
The designs I like use this space as a first stage of heating keeping the wood towards the rear.
One uses the floor (and dark material) to build up more heat..
The second uses (best I can Tell) a dark outdoor privacy screen hung vertically just past the glass..

Both of these units (as I understand) are used to dry 'furniture grade' material so they have fans to control the heat/air mix.

If you go for it, please do some recording of readings and pass them along!

 

[RobertNH]

I'll make a prediction. I will assume your weather was like it was here in the very north of NJ. I'm only 20 miles or so from CT.

If you are weighing in grams you will probably find that your pieces are a couple grams lighter right now. Their surface became very dry today so they will easily soak up some humidity tonight. They will be about 10-15 grams heavier tomorrow with their nightly followed by a rainy day with no drying and probably some more uptake. Weighing in Oz you might see no difference. If your wood was still very green you will measure some drying progress. The uncovered pieces will be 2-500 grams (up to a pound) heavier if it rains. That will depend on species and their size.

You are going to get me to buy a gram scale.. aren't you.. LOL!
I'll see what I can find..

 

[RobertNH]

Okay Paul.. I'll just ask you from now on.. LOL.
You got that one right!
Another drizzly day and readings were only 2ozs lighter through-out all.

Today (Sunday) will be bright and dry!
Much needed..

And I did find a gram scale!
All readings from here on in will be in grams.

 

[RobertNH]

I may start another thread on this if I don't get responses.

I believe, right now, the only true way of knowing MC content is by weight.

If you have a 'known' at 50% moisture
And you have a 'known' at 20% moisture
I do believe you can have a 'known' at any weight

If I had a 'known' at 35% (or several points between), I believe I could create a formula (the curve)

If you know of someone, a link of someone, a belief of someone, that has done this..
Please send it my way

Outside of that,
Opinions and suggestions are welcomed.

 

[paul bunion]

I may start another thread on this if I don't get responses.

I believe, right now, the only true way of knowing MC content is by weight.

If you have a 'known' at 50% moisture
And you have a 'known' at 20% moisture
I do believe you can have a 'known' at any weight

If I had a 'known' at 35% (or several points between), I believe I could create a formula (the curve)

If you know of someone, a link of someone, a belief of someone, that has done this..
Please send it my way

Outside of that,
Opinions and suggestions are welcomed.

All you need is a known moisture content and weight and then you can calculate either moisture or weight from any other value. Real easy.

Take the weight and divide it by 100+ your moisture pct. That will give you what one percentage point weighs in your particular piece of wood. Then with the same piece at a different weight divide it by the one pct number. The quotient will be 100+the current pct.

Example.

Wood at 20% weighs 4500 grams. 4500/120=37.5. Every pct point of water is 37.5 grams. The piece started at 6750 grams. 6750/37.5=180. The piece of wood started at 80%. (Now you know why I harped on using grams).

By knowing the moisture and weight of one piece in a round you can figure any of its sister pieces providing you weighed them all on the same starting day and assuming the moisture is uniform within the round. And bark/heartwood/sapwood differences taken into consideration.

Your graph won't be a curve, it is linear. Remember % moisture is expressed as the water weight compared to the dry wood weight. The dry wood weight never changes. You always have 100% of your wood, that is the 100 in my calculations above.

 

[RobertNH]

That's almost too simple.. LOL
But you've been right on several items so far!

Question: When you base your weight, it's on what? A known piece of wood, Known per (?)?
If it's a known piece.. then how did you know?
I ask not to confront, but to understand..

I just read an article of base conditions of areas in the US that wood can dry to.
Very interesting read.
Given certain conditions, my area (which seems to involve you as well) can dry wood to 11% naturally.
I didn't know that.
Now I'm curious how long it took...

 

[Razo]

I haven't experimented with a tarps, plastic, or cases but here is my experience.

I CSS a living red maple and black cherry tree on aug 18.



Stacked it single row in a spot on my property that gets full morning and some afternoon sun. It is fairly breezy where I live. Both woods pegged my moisture meter upon splitting.





Checked the cherry 36 days later, took some splits, split them again to get a freshly exposed side, and buried the probes of my MM into them. 20-22% moisture content – after 36 days.



The red maple was down to 25% after 42 days. I’ll echo what someone else said, it loses a lot of moisture quick, and then exponentially slows down the lower the MC goes. So my cherry is very burnable at 20%MC, however if I wait longer I can get the MC down below that. Good if you are in a pinch though.

 

[RobertNH]

Thank you Razo!
Good solid info.

 

[solarguy2003]

Excellent idea. Here's my idea/thread where I built a 12.5' x 28' hoop house/greenhouse to do exactly this.

https://www.hearth.com/talk/threads...to-store-and-dry-wood-working-awesome.129149/

All the juicy pictures and cost breakdown are on page 2.

Summary: Worked great. Probably important to seal the floor/ground to prevent moisture from migrating into the enclosure.

I put a cheap box fan on a thermostat to come on at 90-95F, to guarantee that every time the fan went on, it would be removing hot humid air.

Some wood that I put in there came from my 1+ year old stash, which was piled and tarped, with the tarp suspended above the pile. That wood measured 14-15% when I put it in the greenhouse. A few sunny weeks later, it (the same exact marked test pieces) measured 0-3% moisture.

The new green wood dropped from high 40's % moisture, to middle 20's % moisture, as measured with a cheap ebay 4 prong moisture meter. I have also compared the results of the moisture meter with a few pieces that I verified, using the weigh, bake, weigh method, which is pretty accurate, if tedious. The meter was surprisingly accurate.

 

[RobertNH]

Excellent idea. Here's my idea/thread where I built a 12.5' x 28' hoop house/greenhouse to do exactly this.

https://www.hearth.com/talk/threads...to-store-and-dry-wood-working-awesome.129149/

All the juicy pictures and cost breakdown are on page 2.

Summary: Worked great. Probably important to seal the floor/ground to prevent moisture from migrating into the enclosure.

I put a cheap box fan on a thermostat to come on at 90-95F, to guarantee that every time the fan went on, it would be removing hot humid air.

Some wood that I put in there came from my 1+ year old stash, which was piled and tarped, with the tarp suspended above the pile. That wood measured 14-15% when I put it in the greenhouse. A few sunny weeks later, it (the same exact marked test pieces) measured 0-3% moisture.

The new green wood dropped from high 40's % moisture, to middle 20's % moisture, as measured with a cheap ebay 4 prong moisture meter. I have also compared the results of the moisture meter with a few pieces that I verified, using the weigh, bake, weigh method, which is pretty accurate, if tedious. The meter was surprisingly accurate.

Welcome Solarguy to 'my' experiment!
I appreciate those that have done inputting their experience!

I will read through your thread and see what you have done.
I've only glanced so far and see there's some interesting info there!

I've learned a lot from this experiment.
But nothing is greater than first hand experience.
Again 'Thank You' for chiming in.

I am convinced, right now, that weight is an extremely important part.
MC or DMM with temp and species is still a 'surface' reading.
Weight and using MC (surface), equating for size, will put you very close to reality.

I've moved my first load from the Solar Kiln and re-stacked today.
Surface readings at 18%
Weight at 20%
3 weeks of 66% good weather
Started before I could read beyond 32% (now can go beyond)

Static pile is at 40% (original wood)

 

[paul bunion]

Welcome Solarguy to 'my' experiment!
I appreciate those that have done inputting their experience!

I will read through your thread and see what you have done.
I've only glanced so far and see there's some interesting info there!

I've learned a lot from this experiment.
But nothing is greater than first hand experience.
Again 'Thank You' for chiming in.

I am convinced, right now, that weight is an extremely important part.
MC or DMM with temp and species is still a 'surface' reading.
Weight and using MC (surface), equating for size, will put you very close to reality.

I've moved my first load from the Solar Kiln and re-stacked today.
Surface readings at 18%
Weight at 20%
3 weeks of 66% good weather
Started before I could read beyond 32% (now can go beyond)

Static pile is at 40% (original wood)

What do you mean by weight at 20%? If that's the amount of weight lost it would be pretty impressive.

 

[RobertNH]

What do you mean by weight at 20%? If that's the amount of weight lost it would be pretty impressive.

Weight of wood and 20% moisture content in the piece itself.
Since the surface reading is 18% (MC), and the weight reading is 20%, I can be 'fairly certain' the piece is no greater than 20%.

With the 'static' pile being 40% (after 3 weeks), I can say I've lost 20% moisture over 3 weeks (again, with a fair amount of certainty).
The issue for me, is I do not really know what the start content was.
When I started this experiment, I could not read above 32% with any certainty.

 

[RobertNH]

The file is up for anyone that wishes to use or examine.
I would like 'those that know' to examine and add what is there and correct.
I do believe it to be solid on information collected.

PM me and I will give you the link.
Once administration believes it to be 'solid', then show me how to post it for all.

 

[RobertNH]

Update going into season 2.

The Solar Kiln is still the best drier I have.
Though small (face cord only), it works great!

This year plenty of free grabs of fresh cuts to be had and actually had to stop. Good problem to have!

The Big Box unit is gone. Just didn't cut it..
The S&G covered has become the secondary drying as it leaves the Kiln.
I've re-worked the cover from the original design and still working on that a bit.
Need to learn how to weld plastic to make a good cover.

Temps in it are 10-15% less than the Kiln, but still, today 30F outside and the temp inside is 50F.
The Kiln approaching 60F

I love how this experiment went. Learned a lot from it, through trial & error, but mainly from your all input!

Thanx Folks!

 

[Poindexter]

I have read this thread quite a few times and did find your data useful to me in my own kiln build. I am running 8-10 cords annually though, so I had to go bigger. I did especially appreciate seeing all your designs worked, that was a good indicator that whatever I came up with was probably going to be better than not doing anything.