# Made a small lightbulb kiln and cannot find much schedule info.



## Blueglass

I have looked a lot for a schedule to run the kiln and have found some rough ideas but not a lot of solid info. I would like to avoid case hardeneing or other problems. Should I open it up and turn it off for a few hours once a week to let the wood climatize? Any ideas would be appreciated.


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## justallan

I'm just following to learn something. Don't mind hitch hikers do you?

Reactions: Like 2 | Agree 2


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## HomeBody

I know what case hardening is on metal, but never heard that term used for wood. Can the outside of the wood really get hard with the inside normal? Gary


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## norman vandyke

justallan said:


> I'm just following to learn something. Don't mind hitch hikers do you?


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## daugher12

I have a small light bulb kiln. I use it for pen blanks, pot call blanks, up to about 2x2 stuff. I put mine on a timer and usually cycle it on 4 hours off 4 hours. I've never put fresh cut stuff in, I usually let it air dry for a few weeks first.


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## Blueglass

With a 60 watt bulb seems to be holding 96 degrees. I am thinking I will open once a week and check mc and then leave it open overnight. At the point I get it around 9% i will put in a 100 or bigger watt bulb to go over 135 dgrees for bug kill over night and done. Does this sound feasible.


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## TimR

Les, the issue of case-hardening is real, and I'm sure there are tests for it, but from what I've heard, the key is slow drying. If a piece gets case hardened, it may exhibit some wonky movement after recut and having the internal stresses relieved.
My approach, and I've not had any issues with turned stuff, is slow drying. I start with a 40W bulb in my dishwasher kiln, and that gets up to about 95F like your 60W, and I try not to open too much, leaving the humidity inside to help slow down the internal water loss. I'll let that go for a week with really wet pieces, then I'll swap out the 40W for a 60W to bring temp up to about 105-115, and leave for several days. I'll open up a bit more often to let some humidity out at this point, but the dishwasher door does a good job of leaking excess humidity.
After about 2 wks, if I don't see any moisture in the dishwasher when I open it, I put both bulbs in there to get temp up to 130-135, as a finish off for about a day or so.
I'm definitely open for comments from the guys who have 'real' kilns to see if that's a reasonable approach.

Reactions: Agree 1


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## Blueglass

Thanks Tim. So far everything I put in reached emc before I put it in. Here in FL I cannot get below 16% right now and 12% is best at all. I am doing 4/4 to 8/4 boards.


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## ripjack13

@ghost1066

Reactions: Thank You! 1 | Agree 1


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## ironman123

This is really interesting.

Reactions: Agree 1


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## ghost1066

I'm guessing Marc @ripjack13 wanted me to see this one. I read through the thread and the one thing I keep seeing or not seeing is where there were vents added to your kilns. That would be my first concern before I looked at how long to cook wood. @Blueglass there is probably a good reason for not finding hard set time frames for drying. The fact that each kiln, wood type, area you are in, all play into how your product will dry. What works in Arizona is going to be different in Oregon. Having said that the tips I can give are vent your kilns and even add a small fan to help with air flow but get that trapped moisture out. The reason you are opening your kilns seems to be to rid it of trapped moisture or to acclimate it. Both things need to be addressed which brings us back to the vents which takes care of most of that. 

When I started learning about kilns the first rule was leave it shut, period. It is doing the job and if it is built correctly you let it work. Shutting the light off for a few hours is no different to me than the sun going down and cooling my kilns, I checked the big one at 10:30 this morning and it was sitting at 119* already and it has been closed since July 8th. 

Now here is what I go by right or wrong it seems to work. 5 weeks per inch on wet wood that is a slab or bowl blank but that is in a kiln running hotter so maybe add a week. Pen blanks and spindles dry MUCH faster and might be ready in a few days. I have had pen blanks dry in as little as 3 days and to be honest we don't put them in the kiln now they air dry so fast. Hope that helps some.

Reactions: Thank You! 2 | Informative 2


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## ripjack13

Yes sir....thanks for the info Tom.


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## Blueglass

Thanks and yes I have 2" hole for inlet and a 3" fan pulling air out. Thanks again.


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## ghost1066

Blueglass said:


> Thanks and yes I have 2" hole for inlet and a 3" fan pulling air out. Thanks again.



Just that bit of information answers almost all your questions. You have no need to open your kiln since you are drawing outside air in and venting the moisture filled air out. Opening your kiln is simply slowing the process since the kiln then has to start over with the "new" air that was let in all at once. You should be good to go just letting it run and checking it depending on the thickness of the blanks you are drying at the time.

Reactions: Like 1 | Thank You! 1


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## daugher12

I did vent mine at the top sides. I have a computer fan blowing across the wood from the bottom to circulate the air.


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## Kevin

I started out with a "light bulb kiln" with a computer fan and what Tim describes honestly, is all you need to know. I do suggest a more intentional vent is necessary than just a leaky dishwasher door though.  

Drying wood is a science if you are drying large charges of stacks of dimensional lumber that are fresh off the mill, and some species are much more finicky than others, but drying small pieces like we do it is hard to screw it up. As long as you apply a way to force the moisture out of the wood but not too quickly, have some moderate ariflow withing the kiln to be able to pull the moisture off the surface of the wood as it is getting released (or it will get moldy) and you give the moisture an escape path out of the box, your wood will dry with few defects. 

Drying large stacks of framing lumber which is full of water is the reason for drying schedules. You don't need a schedule. You need a slow-drying chamber that pulls moisture out, and expels it.

Reactions: Like 2 | Thank You! 1 | Agree 1 | Informative 1


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