# Solar kiln for hardwoods



## Woodsplitter67 (Oct 18, 2018)

My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
The first day I ran my kiln it was a cooler day no more than 76 degrees and within a couple of hours of setting up the kiln it was over a 110. I used an air probe for my smoker to measure the internal temperature of the Kiln at various points.
I did all of this to see if I ever get jammed up that I could actually season a Year's worth of firewood over the course of the summer I also did another experiment with nothing but Oak and even larger splits those splits started in the upper 30s to low 40s and I got them down to sub 20% moisture content in 2 months


----------



## Jan Pijpelink (Oct 18, 2018)

Great stuff! Thanks for posting.


----------



## Akon (Oct 18, 2018)

I put together a temporary solar kiln in mid September when I was moving wood and saw I had 1.5 cords of ash that was still low 30s. Used scrap wood and 6 mil plastic 12x6', 7' tall. 3 rows on pallets inside. Hoping it's good to go by Feb. Part sits under the deck so access point isn't in snow. I wasn't sure how big to make vent on top in balance of trying to keep it warm vs letting moisture out. I just used 1" pvc in front and back. I get consistent wind off the water; so, hopefully that's enough.


----------



## showrguy (Oct 18, 2018)

Thanks for starting this Woodsplitter, my problem is I live in the woods and there's no way I can get full sun all day..


----------



## chemie (Oct 18, 2018)

Woodsplitter67 said:


> My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
> Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
> My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
> The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
> ...


Thanks for sharing your experience. I am very interested. I have four 4x8 and two 4X4 Landmann brand wood racks. We don’t have much space in our backyard so I just gathered about 2.5 cords of seasoned firewood from Craigslist to use in our newly installed BK AF25 insert. We live close by to a city forest filled with fallen dead  oak trees from previous storms. I recently cut and split about 10 logs. The moisture of splits range %23 to %30. I’m hoping they could go below %20 so that we can use them in March-April. For next year though, if I could make sun kiln work  , I can use it on the oak woods from the fallen dead trees in coming May.
So if I could make it work, they could be even dry in 2 months ( May- June)? 
Do you have more pics of your set up that you can share?
Thanks!


----------



## Woodsplitter67 (Oct 18, 2018)

showrguy said:


> Thanks for starting this Woodsplitter, my problem is I live in the woods and there's no way I can get full sun all day..



So with out a large solar gain your drying time will increase, but thats not to say you cant get quality results. In full sun i can easy make 2 runs and get sub 20% on both runs. So in your case eather a larger kiln, 2 kilns or just 1 kiln and 1 run. I would say try a  1 rack kiln run and post results which will help people similar to your situation. I believe my first run cost me less than 50 bucks to do and I'm still sitting on some of the material to put together another kiln


----------



## Woodsplitter67 (Oct 18, 2018)

chemie said:


> Thanks for sharing your experience. I am very interested. I have four 4x8 and two 4X4 Landmann brand wood racks. We don’t have much space in our backyard so I just gathered about 2.5 cords of seasoned firewood from Craigslist to use in our newly installed BK AF25 insert. We live close by to a city forest filled with fallen dead  oak trees from previous storms. I recently cut and split about 10 logs. The moisture of splits range %23 to %30. I’m hoping they could go below %20 so that we can use them in March-April. For next year though, if I could make sun kiln work  , I can use it on the oak woods from the fallen dead trees in coming May.
> So if I could make it work, they could be even dry in 2 months ( May- June)?
> Do you have more pics of your set up that you can share?
> Thanks!


So the biggest asset to the kiln is the sun and solar gain.. even though i have not proformed a run in the spring and winter. I did a run untill the latter part of october and the temps along with the diration of sun was not what i would consider ideal for seasoning 

Also. The wood needs to season on its own  some for the process to work. Cutting wood and putting it in the kiln will only hinder the results. The center of the split will have alot of moisture in it and the ends will have shrunk down making it harder for the MC of the wood to drop..


----------



## chemie (Oct 18, 2018)

Woodsplitter67 said:


> Also. The wood needs to season on its own  some for the process to work. Cutting wood and putting it in the kiln will only hinder the results. The center of the split will have alot of moisture in it and the ends will have shrunk down making it harder for the MC of the wood to drop..


Do you consider wood obtained from fallen dead trees as pre-seasoned and can directlygo into kiln? I can talk about only one experience that I recently cut 10 logs from a dead tree and after the split , MC was about or below 30. I’m posting some pics so that you can have visual of the conditions of the wood.


----------



## Woodsplitter67 (Oct 18, 2018)

chemie said:


> Do you consider wood obtained from fallen dead trees as pre-seasoned and can directlygo into kiln? I can talk about only one experience that I recently cut 10 logs from a dead tree and after the split , MC was about or below 30. I’m posting some pics so that you can have visual of the conditions of the wood.
> 
> 
> 
> ...



If your sub 30 i thinks your going to be ok its going to be hard ro tell from the pics but the wood dose not look green or wet. ..i can tell when the wood is ready by when the stacks start to shift, then you know you have achieved shrinkage..


----------



## showrguy (Oct 18, 2018)

Woodsplitter67 said:


> So with out a large solar gain your drying time will increase, but thats not to say you cant get quality results. In full sun i can easy make 2 runs and get sub 20% on both runs. So in your case eather a larger kiln, 2 kilns or just 1 kiln and 1 run. I would say try a  1 rack kiln run and post results which will help people similar to your situation. I believe my first run cost me less than 50 bucks to do and I'm still sitting on some of the material to put together another kiln


Well, I'm pretty good at keeping a few years ahead, but this solar kiln stuff has my attention..

I sort of tried it this summer with a load of hickory slab wood on my dump trailer, I wrapped the 4 sides and top with a piece of plastic from my sisters green house, left it on for about 6 weeks, some days temps would hit 135 deg.

Since then, they replaced the plastic on the g-house, I got the old stuff, so I have plenty to play with..


----------



## chemie (Oct 18, 2018)

showrguy said:


> Well, I'm pretty good at keeping a few years ahead, but this solar kiln stuff has my attention..
> 
> I sort of tried it this summer with a load of hickory slab wood on my dump trailer, I wrapped the 4 sides and top with a piece of plastic from my sisters green house, left it on for about 6 weeks, some days temps would hit 135 deg.
> 
> Since then, they replaced the plastic on the g-house, I got the old stuff, so I have plenty to play with..



What was the before and after MC reading of 6 weeks trial?


----------



## showrguy (Oct 18, 2018)

chemie said:


> What was the before and after MC reading of 6 weeks trial?


I did'nt check it after, before though most was under 20%, but a few were 30 +%, I also had a box fan in there blowin the air around..


----------



## Poindexter (Oct 18, 2018)

Awesome, thank you.  This build is more or less the prototype I should have done before I built mine.


----------



## shortys7777 (Oct 18, 2018)

Is the plastic touching the ends of the wood? By the pic it looks like it's wrapped pretty tight. Clearly your still getting good results. I'm going to try this in the spring. Thanks


----------



## Poindexter (Oct 19, 2018)

So basically you got a couple of these from Home Depot:




Placed them end to end.  The vertical 2x4s at each end.  Some rope for a ridgepole, scrap plastic, and you can season two loads (of hardwood) each summer at your location?

Nice job.


----------



## Poindexter (Oct 19, 2018)

The thing I love about this build is @Woodsplitter67 didn't really have to buy anything or use much in the way of tools.

Those H-D racks are everywhere, inexpensive, lots of folks have them already.  

The 2x4s he used were plain old 8 footers.  No cutting.

For proof of concept you could get the cheapest plastic available.  I am using 6mil clear and getting about 18 months per kiln cover, but if you want to just try this you could get the clear plastic drop cloth in the paint aisle for a lot less money.

He did use some paracord, or similar, but what 50, 55 feet?  Under ten bucks even up here, more like $3 or 4, even after shipping to Alaska. 

Starting from scratch and paying Fairbanks prices I could duplicate this build under $100.

I am willing to bet most of you have most of the parts required laying around already.

IIRC his has an open bottom and three grapefruit sized holes at the top per cord, he is seeing 110s dF, and it works.  I am running one cantaloupe sized opening at the top for two cords with a vapor impermeable floor but the bottom edge of the roofing loose and free.  I do see 140s dF in the summer, partly because I get 18+ hours of direct sunlight daily on mine at 64 degrees north.

I do agree solar gain is key.  Keeping the rain off is nice, but solar gain, high internal kiln temperature, lowers the target EMC (equilibrium moisture content) and increases the diffusion gradient between where the wood is and how dry it is trying to be to reach equilibrium.   Solar gain, a hot kiln,  makes the wood dry faster.


----------



## Poindexter (Oct 19, 2018)

@shortys7777 

As far as plastic touching the ends of the splits, what I see is when ambient is below freezing the moisture coming out of the wood condenses on the plastic and runs down.  With ambients above freezing I don't see condensation on the inside of the plastic, i think then the water is mostly going out the top as vapor.


----------



## shortys7777 (Oct 19, 2018)

Thanks for the clarification. I have everything needed laying around except plastic. That'll be a purchase this winter.


----------



## Woodsplitter67 (Oct 19, 2018)

shortys7777 said:


> Thanks for the clarification. I have everything needed laying around except plastic. That'll be a purchase this winter.



The plastic is touching the ends of the splits, the bottom end of the plastic goes all the way down to the 2x4 rail that the splits sit on. There is nothing under the first row of splits to allow the air to work its way through the stacked wood and out the top vents.


----------



## Easy Livin’ 3000 (Oct 23, 2018)

Woodsplitter67 said:


> My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
> Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
> My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
> The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
> ...


Good stuff, WS67.  Thanks for doing the work and reporting back to The Community.

And to top it all off, you got Poindexter's adulation.  That's something.


----------



## rygar (Oct 24, 2018)

so with a solar kiln, how do you prevent the grain ends from clogging from drying too quickly?


----------



## Woodsplitter67 (Oct 24, 2018)

ED 3000 said:


> Good stuff, WS67.  Thanks for doing the work and reporting back to The Community.
> 
> And to top it all off, you got Poindexter's adulation.  That's something.



Thanks ED i really never planned to post this in its owne thread. I didnt take alot of photos of what i have been doing and i have yet to take more data like how much the splits actually dropped in MC. My next run which will be this spring i will take the time to get more information to share. Im going to be doing a run on white oak this spring.


----------



## Woodsplitter67 (Oct 24, 2018)

rygar said:


> so with a solar kiln, how do you prevent the grain ends from clogging from drying too quickly?



Best bet is to let the wood season for 2 months prior to the kiln run. That should be good enough to let the rest of the MC run out...


----------



## rygar (Oct 24, 2018)

Woodsplitter67 said:


> Best bet is to let the wood season for 2 months prior to the kiln run. That should be good enough to let the rest of the MC run out...


excellent.  all my wood has been C/S/S for a minimum of 6 months.  so its all eligible for proper solar kiln.


----------



## rygar (Oct 24, 2018)

Woodsplitter67 said:


> So with out a large solar gain your drying time will increase, but thats not to say you cant get quality results. In full sun i can easy make 2 runs and get sub 20% on both runs. So in your case eather a larger kiln, 2 kilns or just 1 kiln and 1 run. I would say try a  1 rack kiln run and post results which will help people similar to your situation. I believe my first run cost me less than 50 bucks to do and I'm still sitting on some of the material to put together another kiln



how long is a run?


----------



## Woodsplitter67 (Oct 24, 2018)

rygar said:


> excellent.  all my wood has been C/S/S for a minimum of 6 months.  so its all eligible for proper solar kiln.




Yes your ready to go.
 Thats plenty


----------



## Woodsplitter67 (Oct 24, 2018)

rygar said:


> how long is a run?



So how long you run your kiln will depend on a couple of things. Time of year, species of wood, and sunlight. All of this will factor into how long you will need to run the kiln to achieve the desired MC. Your in PA so your not far from me, but its going to be hard for me to help you with the seasoning time. Im in direct sunlight, and I dont have any real experience with partial sun. If I were in an area with partial sun I would do multiple  Kilns and more likely have to run the kill the entire summer to achieve the desired moisture content I would do a run with Hardwoods splitting the wood this spring letting it season for a couple of months and run the kiln for the entire summer. I would take some internal temp readings when the sun hits it to see what the solar gain is and pull a split to see how much MC you have dropped. Once you do one run in the kiln you will have a better idea of what to expect. From what i can remember @Poindexter  needs to run his most of the summer, while i can do 2 runs in  the summer if needed.  How much will you need to season


----------



## Dmitry (Oct 24, 2018)

Woodsplitter67 said:


> My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
> Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
> My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
> The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
> ...


Where do you cut holes and how to make sure that no water can get in those holes


----------



## Woodsplitter67 (Oct 25, 2018)

Dmitry said:


> Where do you cut holes and how to make sure that no water can get in those holes



I cut a hole on eather end in a u shapr not removing the plastic bit making it into a flap amd i  just taped it up. I also did one in the middle of the apex of the roof. You may get a little water in but not much. All the vents are at the top so not alot of water will run down the plastic into the hole.


----------



## mcstatz5829 (Oct 27, 2018)

Can you post more pictures from different angles?  Do you have any pictures of the rack and stack before wrapping?


----------



## Woodsplitter67 (Oct 27, 2018)

mcstatz5829 said:


> Can you post more pictures from different angles?  Do you have any pictures of the rack and stack before wrapping?



Check out post 15. Thats what itlooks like, thats how the wood is stacked nothing special. It can be any rack all wood bottom, metal ends it dosent matter the lenth could be 20ft, 16, 8ft. You can do 3 racks deep and 6ft high. One kiln 20long 4.5 wide and 6ft high will yeald 4.21 cords per run.  
I dont have additional pics as i had no plans to start a thread like this. I will do a better job of this in the future and will be able to post more indepth
I encourage you to experiment with it. The worst thing that happened to me was my cherry was 2% and my oak was 9%. . You really cant go wrong. Your woods not going to spontaneously explode it's either going to be perfectly seasoned a little under seasoned or a little over seasoned. Eather way.. you've made progress and learnd something and now you know for next time.


----------



## Easy Livin’ 3000 (Oct 27, 2018)

Woodsplitter67 said:


> Check out post 15. Thats what itlooks like, thats how the wood is stacked nothing special. It can be any rack all wood bottom, metal ends it dosent matter the lenth could be 20ft, 16, 8ft. You can do 3 racks deep and 6ft high. One kiln 20long 4.5 wide and 6ft high will yeald 4.21 cords per run.
> I dont have additional pics as i had no plans to start a thread like this. I will do a better job of this in the future and will be able to post more indepth
> I encourage you to experiment with it. The worst thing that happened to me was my cherry was 2% and my oak was 9%. . You really cant go wrong. Your woods not going to spontaneously explode it's either going to be perfectly seasoned a little under seasoned or a little over seasoned. Eather way.. you've made progress and learnd something and now you know for next time.


WS67, you are creating a revolution!  

Poindexter came before you, but he was a little too intellectual (or maybe a lot) for the masses.  It's often the reluctant who spark such things.  

I've wanted a kiln system myself for a few years now. But you did it.

I hope to see shrink wrapped woodstacks popping up everywhere soon.

Good work!


----------



## Woodsplitter67 (Oct 28, 2018)

ED 3000 said:


> WS67, you are creating a revolution!
> 
> Poindexter came before you, but he was a little too intellectual (or maybe a lot) for the masses.  It's often the reluctant who spark such things.
> 
> ...



Thanks  ED..


----------



## chemie (Oct 28, 2018)

Woodsplitter67 said:


> Check out post 15. Thats what itlooks like, thats how the wood is stacked nothing special. It can be any rack all wood bottom, metal ends it dosent matter the lenth could be 20ft, 16, 8ft. You can do 3 racks deep and 6ft high. One kiln 20long 4.5 wide and 6ft high will yeald 4.21 cords per run.
> I dont have additional pics as i had no plans to start a thread like this. I will do a better job of this in the future and will be able to post more indepth
> I encourage you to experiment with it. The worst thing that happened to me was my cherry was 2% and my oak was 9%. . You really cant go wrong. Your woods not going to spontaneously explode it's either going to be perfectly seasoned a little under seasoned or a little over seasoned. Eather way.. you've made progress and learnd something and now you know for next time.



Let us know when you do a new run in Spring. And please take lots of pics for people who are not so handy like me. 
I’d like to run a trial test at the same time with you in Spring. Then we can compare the results.


----------



## Woodsplitter67 (Oct 28, 2018)

chemie said:


> Let us know when you do a new run in Spring. And please take lots of pics for people who are not so handy like me.
> I’d like to run a trial test at the same time with you in Spring. Then we can compare the results.



Ok.. rhats cool.. im going to do white oak.. and im going to do it 2 kind of ways..


----------



## showrguy (Oct 28, 2018)

Woodsplitter67 said:


> Ok.. rhats cool.. im going to do white oak.. and im going to do it 2 kind of ways..


Did I read somewhere that you tried the same thing over winter with not much for results ??
I'm working up a couple of cords of Standing dead Oak, and was thinking of wrapping it, then was thinking just top cover for winter ??


----------



## chemie (Oct 28, 2018)

Woodsplitter67 said:


> Ok.. rhats cool.. im going to do white oak.. and im going to do it 2 kind of ways..



Let me know ahead of time when you are going to start so that I can go to the near by forest to cut from fallen dead white and red oak trees.


----------



## mcstatz5829 (Oct 28, 2018)

Woodsplitter67 said:


> Check out post 15. Thats what itlooks like, thats how the wood is stacked nothing special. It can be any rack all wood bottom, metal ends it dosent matter the lenth could be 20ft, 16, 8ft. You can do 3 racks deep and 6ft high. One kiln 20long 4.5 wide and 6ft high will yeald 4.21 cords per run.
> I dont have additional pics as i had no plans to start a thread like this. I will do a better job of this in the future and will be able to post more indepth
> I encourage you to experiment with it. The worst thing that happened to me was my cherry was 2% and my oak was 9%. . You really cant go wrong. Your woods not going to spontaneously explode it's either going to be perfectly seasoned a little under seasoned or a little over seasoned. Eather way.. you've made progress and learnd something and now you know for next time.


 Are you going to burn those as is or let them regain moisture?


----------



## Woodsplitter67 (Oct 28, 2018)

mcstatz5829 said:


> Are you going to burn those as is or let them regain moisture?



I burned some of it.. that stuff caught quick and burned really well.. i didnt burn it all though.. im sure its regained some moisture


----------



## showrguy (Oct 28, 2018)

Woodsplitter67 said:


> I burned some of it.. that stuff caught quick and burned really well.. i didnt burn it all though.. im sure its regained some moisture


Have you treid this over winter ? Results ?


----------



## Akon (Oct 28, 2018)

I am going to do a run or two in the spring or summer with red oak and ash on yet to be cut trees. Need to finally get ahead on my supply. Don't have a great spot for a kiln that gets good sun near my wood, so am considering putting it temporarily on part of the asphalt driveway that is out of the way for ~ 4 weeks.


----------



## Woodsplitter67 (Oct 28, 2018)

showrguy said:


> Have you treid this over winter ? Results ?



The kiln need to get warm.. winter sun and cold temps are not ideal


----------



## showrguy (Oct 28, 2018)

Woodsplitter67 said:


> The kiln need to get warm.. winter sun and cold temps are not ideal


Ok, Thanks..


----------



## mtarbert (Oct 28, 2018)

Woodsplitter67 said:


> My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
> Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
> My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
> The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
> ...


 


              Do you think a small solar powered vent fan would help ?


----------



## Poindexter (Oct 29, 2018)

@ED 3000 , point well taken.  

I posted a link to a journal article in one of my threads about how hot how fast.  The guys running lumber kilns trying to make finished boards keep the kiln temperature below 95dF until the wood starts to shrink.  

When your stacks are moving, tipping, leaning, whatever, when they are shrinking you have all the water out of the sap tubules and it is "time" to turn up the heat.  

As burners we aren't too terribly worried about warping and cupping and end grain checking.  The folks with a kiln full of clear mahogany are worried about that.  So it could be we could let out kilns get hotter sooner then those guys, but is is a place to start.

FWIW I keep my kilns internal temp below 95dF until I see shrinkage.  I have zero data on what the limit really is.  If you have a split that measures 15% MC on the outside and 30+%MC on the inside, you turned your kiln temperature up too soon.


----------



## Easy Livin’ 3000 (Oct 29, 2018)

Poindexter said:


> @ED 3000 , point well taken.
> 
> I posted a link to a journal article in one of my threads about how hot how fast.  The guys running lumber kilns trying to make finished boards keep the kiln temperature below 95dF until the wood starts to shrink.
> 
> ...


You know I'm a big fan of your work, PD.  I'm just way too lazy (or worn out from other stuff that requires attention) to do a build that requires too much effort.  

So far, I've filled a couple of round cages made of welded fencing and dropped big clear bags over them.  After a few weeks, the bags stopped showing condensation on the inside.  Clearly it worked!

Here's an idea for a commercial modular solution:. Shelterlogic sells big solar firewood kilns, but no matched racking solutions.  Couple the racks that WS67 used with covers made of the material Shelterlogic uses on their kilns and greenhouses.  The options should start with a "face cord" model, a 2/3 cord model (two racks back to back), and a one cord model (3 racks). You'd have to figure out the venting. Plug and play.

I don't think this is an idea that would make a ton of money, but it would probably be worth doing.


----------



## SuperJ (Oct 29, 2018)

Woodsplitter67 said:


> The kiln need to get warm.. winter sun and cold temps are not ideal



Wouldn't the low OA dewpoint in the winter play to your advantage?  You need less of a temperature lift when it's really cold, to a have really low %rh.
The low angle and shorter daylight hours would be a downer though. 

This is a nice simple dewpoint/humidity/temp converter to play with http://www.dpcalc.org/


----------



## mcstatz5829 (Oct 29, 2018)

I like this idea more and more.  I may relocate to another state in a few years.  A cheap kiln will keep the wood stockpile low and prevent overinvestment. 

I suppose if I had roots and plenty of acres it wouldn’t matter much, but in my situation a kiln makes much more sense than stockpiling 3 years of wood.


----------



## Woodsplitter67 (Oct 30, 2018)

mcstatz5829 said:


> I like this idea more and more.  I may relocate to another state in a few years.  A cheap kiln will keep the wood stockpile low and prevent overinvestment.
> 
> I suppose if I had roots and plenty of acres it wouldn’t matter much, but in my situation a kiln makes much more sense than stockpiling 3 years of wood.




At one time i was sitting on 13 to 14 cords. I burn just about 4 cords. I now sit on 9. my wood is cut down because if i need more i can just season more up kinda on demand.


----------



## Woodsplitter67 (Oct 30, 2018)

showrguy said:


> Did I read somewhere that you tried the same thing over winter with not much for results ??
> I'm working up a couple of cords of Standing dead Oak, and was thinking of wrapping it, then was thinking just top cover for winter ??



So far i havent run the kiln in the winter. The kiln needs heat to work. The low sun and cold temps are ont ideal for wood drying. If you were to get temps in the 70s for a couple weeks you could see some progress, but were past that point


----------



## Woodsplitter67 (Oct 30, 2018)

SuperJ said:


> Wouldn't the low OA dewpoint in the winter play to your advantage?  You need less of a temperature lift when it's really cold, to a have really low %rh.
> The low angle and shorter daylight hours would be a downer though.
> 
> This is a nice simple dewpoint/humidity/temp converter to play with http://www.dpcalc.org/



Im not sure why, but our wood seasons better with heat. Wood seasoning slows in winter late fall and spring. Speeds back up when the temps climb. I'v  checked my wood in fall and then spring and its barely moved. Let the summer sun and heat get to it and progress is made alot quicker. I really think its a combination of the temp and difference in RH. I just know this.. it works dam good doing it this way.


----------



## Dmitry (Nov 3, 2018)

Woodsplitter67 said:


> My solar kiln, was made from the big box store wood racks as an experiment to see if i could season hardwoods like @Poindexter has done with softwoods.
> Materials used were wood racks, 2x4 pressure treated, 6 mil clear plastic, a small roap, contractors stretch wrap and a staple gun
> My wood racks were 5 inches above ground and sitting on 2x4 for a total of aprox 8 inches. I secured some two-by-fours on the ends and tied a rope between them making a roof over the top I put plastic around the racks and secured the bottom of the plastic to the first row of firewood with contractors stretch wrap and some Staples I cut in 3 vents to on either end approximately the size of a grapefruit and one smaller one in the middle this would was split in May and sat on the racks until the week of July 8th in which I started the kilm all of my splits were large 6 to7 in thick and 18 in Long and those splits at in the kiln until October when I open the Kiln the Cherry splits were down to approximately 2% and all of the oak was down to 9% so given that you could easily do two runs with in a rack
> The way that the kiln needs to be set up for Hardwoods is you need it in a full sun area you do not want the venting to be too much as you want the temperatures to get extremely warm within the kiln it does need to vent the moisture out so typically my kiln Ran from anywhere from 110 degrees and I've gotten it as high as 121 degrees
> ...


We had very wet summer here and some of my wood got touched by fungus . I scraped as much as I can. Do you think it’s still Ok to to kiln with wood like this? I think I might kill 2 birds with one stone here. Not let any more autumn moisture to wood  and and bring eventually moisture down to stop fungus inside the pile.


----------



## Dtunes (Nov 3, 2018)

The visible portion of fungi is usually just the fruiting bodies(like flower/seeds in plants) and the majority of the organism is already distributed throughout the substrate. So if you see a mushroom on your lawn, the actual bulk of the organism is far larger in the soil. The same is probably true with the wood, so scraping it off might reduce its ability to spread but won't remove the fungus from the wood.

That being said, I have no experience with solar kilns so I don't know if it will get hot enough to kill or slow the fungus. It might in that summer, I'd guess not during the colder months. 

Fungi also need fairly high moisture levels to grow. If the kiln dries quickly you might reduce the moisture faster than the fungus can grow.

Personally, I wouldn't risk good wood by placing it in the kiln with fungus infested wood, but if the wood is all similarly touched by fungus it might be worth a shot during the summer. I wouldn't try it in the fall unless you have excellent southern exposure and fairly high temps.


----------



## Woodsplitter67 (Nov 3, 2018)

Dmitry said:


> We had very wet summer here and some of my wood got touched by fungus . I scraped as much as I can. Do you think it’s still Ok to to kiln with wood like this? I think I might kill 2 birds with one stone here. Not let any more autumn moisture to wood  and and bring eventually moisture down to stop fungus inside the pile.



You have fungi because your wood is wet and stayed that way. I havent had your issue.  That being said this fungi will not be able to live and prosper if you drive the moisture out. You could kill off the fungi by putting it in a kiln. I think you would be ok. I wouldn't store the wood in the house.. i would kiln the wood, once the fungi is gone put it directly into the stove..hope this helps


----------



## Jotel me this (Dec 1, 2018)

interesting. thanks. im going to build something similar


----------



## wooduser (Dec 6, 2018)

Akon said:


> . I wasn't sure how big to make vent on top in balance of trying to keep it warm vs letting moisture out.




Amazon or Ebay both have wide selections of hygrometers that measure humidity.  They are available in both mechanical and electronic versions.

You might want to consider using a hygrometer along with your thermometer to measure the humidity being generated inside your kiln.  You could also rig up an air velocity telltale  made from paper to measure the amount of humidified air  that is exiting the kiln.  The paper telltale could be arbitrarily calibrated with a series of marks to measure the velocity.

Day X    Temp  120  Humidity 60%  Air velocity Mark 3

Day Z    Temp    80  Humidity 30%   Air velocity  Mark 1

Or whatever.


----------



## ispinwool (Jul 25, 2020)

I'm sorry to dig up an old discussion (but I'm so glad I found it!
I had NO idea we could build a homemade/backyard kiln)
 but I'm wondering if using the thick black
plastic would work as well?  I've always been told that black clothing/cars/etc
get hotter faster...?   I guess it's "whatever works best for your circumstance"...
would there be any reason NOT to?
I'm intrigued!


----------



## Woodsplitter67 (Jul 25, 2020)

ispinwool said:


> I'm sorry to dig up an old discussion (but I'm so glad I found it!
> I had NO idea we could build a homemade/backyard kiln)
> but I'm wondering if using the thick black
> plastic would work as well?  I've always been told that black clothing/cars/etc
> ...


your building a green house over your wood stacks.. ever see a greenhouse with black plastic... never... thinted windows keep a cars interior cooler... the pladtic does not heat the kiln.. the pladtic traps the heat in.. you need sun to get into the kiln to work it.. look in my signature to see how to make one


----------



## ispinwool (Jul 25, 2020)

I hadn't even thought of 'tinted windows'! good point!

Thank you for the info you compiled/shared.  I had no idea that there was a way
to hurry along the drying process for backyard use.  Clever!


----------



## FreddieFire (Feb 20, 2022)

I've been struggling with the 6-mil plastic in my mind because I know it's not very UV resistant. If that stuff sits out in my area very long you can easily tear it apart due to the UV degradation.
Now house wrap on the other hand can weather the sun, wind, rain all season long and it still looks just like it did when it came off the roll. Your design probably needs to be devised around the 9' width, but that would be a small price to pay for having a material that would last years and not be a throw away after each kiln build.
Any thoughts on house wrap given that it's not clear? Home Depot currently sells a 9x150 roll for $105. The 12x100 roll of throw away 6-mil is $70.


----------



## begreen (Feb 20, 2022)

They make UV-treated plastic film for greenhouses. That will last much longer.


----------



## FreddieFire (Feb 20, 2022)

Good point! I'll snoop around at pricing. Plus the added advantage of NOT having to advertise with your woodpile 😁.

Still intrigued by house wrap for some reason ... interested in thoughts.


----------



## begreen (Feb 20, 2022)

Amazon product


----------



## Woodsplitter67 (Feb 21, 2022)

As be green said.. greenhouse plastic. You will get years out of it.  using material that blocks the sun slows the process. The sun is what drives the kiln. Your building a mini greenhouse around the wood.. using house wrap around the wood is putting it in constant shade..


----------



## FreddieFire (Feb 21, 2022)

Thanks, guys. You've got me recalibrated!


----------



## Dfw245 (Apr 21, 2022)

Looks like I'll be joining this trend also. I'm in Texas so I'm sure the heat will be even more of an asset. Also have a bug problem. I'll see if the kiln remedies that


----------



## Woodsplitter67 (Apr 23, 2022)

Dfw245 said:


> Looks like I'll be joining this trend also. I'm in Texas so I'm sure the heat will be even more of an asset. Also have a bug problem. I'll see if the kiln remedies that


 I just responded to the other thread.. you should be ok doing a kiln


----------



## DonTee (Jul 7, 2022)

Question for you guys, and excuse me if it’s already been mentioned. Has anyone ever used their existing woodshed to make a kiln? For example, I have a woodshed with a flat metal roof. It’s green steel that gets pretty hot. How about wrapping the four walls with plastic, and leave some vents on the tallest part but the rafter ends? 

Maybe it wouldn’t trap as much heat in because the roof is solid, but it might do something. Just wondering if it’s been tried before.


----------



## EbS-P (Jul 7, 2022)

DonTee said:


> Question for you guys, and excuse me if it’s already been mentioned. Has anyone ever used their existing woodshed to make a kiln? For example, I have a woodshed with a flat metal roof. It’s green steel that gets pretty hot. How about wrapping the four walls with plastic, and leave some vents on the tallest part but the rafter ends?
> 
> Maybe it wouldn’t trap as much heat in because the roof is solid, but it might do something. Just wondering if it’s been tried before.


There is a member here that has a complete 4 sided board and batton shed.  Pretty sure it is in NC. Can’t recall who it is.  
Found it. 
Post in thread 'Show Us Your Wood Shed'
https://www.hearth.com/talk/threads/show-us-your-wood-shed.181210/post-2525713

It’s gotta be in nearly full sun and well enough sealed to trap the heat but allows moisture out. And really might not have enough time this year.


----------



## Woodsplitter67 (Jul 7, 2022)

DonTee said:


> Question for you guys, and excuse me if it’s already been mentioned. Has anyone ever used their existing woodshed to make a kiln? For example, I have a woodshed with a flat metal roof. It’s green steel that gets pretty hot. How about wrapping the four walls with plastic, and leave some vents on the tallest part but the rafter ends?
> 
> Maybe it wouldn’t trap as much heat in because the roof is solid, but it might do something. Just wondering if it’s been tried before.



 I would just do the kiln and not take a chance of the wood not being ready. You can put the wood on racks, wrap it and still fill the wood shed with next years wood to try to get ahead. Your in upstate NY so it gets cooler faster You will.dry faster and longer with the plastic. I did a test this fall/early winter with a mini kiln and it culd be 50 degrees outside but in the kiln its 85.. your not going to get that with just warmth from a roof in a low sun angle condition.


----------

