Drying Chamber

[Edward Weingarden]

I recently built a drying chamber for my rough turned pieces. It has insulated walls, an incandescent bulb, and a mini dehumidifier in it. It is a sealed box; there are no vent holes in it. I've been gradually bringing the temp up, first with a 40W bulb, then a 60W, and now a 75W. The RH inside the box has gone from 88% to it's current level of 78% over two weeks. The dehumidifier has accumulated about a pint of water, and there is a lot of rain out on the foil faced walls. I choose to use the dehumidifier and not put vent holes in so that my shop doesn't get exposed to all the moisture. Since this is my first experience with this, I'm not sure if the RH should be lower at this point (after 2 weeks). Is the rain out in the chamber "normal"? I know that people use old freezers and put vent holes in them, but I've also read of those who use an enclosed box without vents. I thought the dehumidifier would collect most of the moisture, but that doesn't seem to be the case. Any guidance with respect to RH levels, extent of rain out, etc. would be appreciated. Thanks.

[Kyle Iwamoto]

Rain out?
I made fridge kiln with an old freezer and the RH drops from 88 to 78 in the first day of use with a 40w bulb. I'd say you need vent holes. How big is your chamber? I wouldn't worry about the humidity increase in the shop, unless its poorly ventilated. Normal ventilation should clear out all the excess moisture.

[Edward Weingarden]

Thanks Kyle. The box is 32"W x 24"D x 54"H.

[Brice Rogers]

I'd recommend putting weep holes in the bottom so that the condensation on the foil has a place to drain outside of the box.

I'd also follow the advice of Kyle Iwamoto and add some ventilation and skip the dehumidifier.

[John K Jordan]

Edward,

If ask Sir Google to find "cindy drozda freezer kiln" (without the quotes) you can read what Cindy does, including holes. A huge number of people have followed her instructions.

I think you have to have ventilation so the moisture in the wood will leave the box as it goes comes out of the wood and goes into the air. I have no idea about the ideal RH, I don't remember reading of anyone measuring it, they just dry slow enough to avoid the wood disintegrating. There are plenty of documents and info on kilns so if you want you can read more than you can probably stand.

JKJ

I recently built a drying chamber for my rough turned pieces. It has insulated walls, an incandescent bulb, and a mini dehumidifier in it. It is a sealed box; there are no vent holes in it. I've been gradually bringing the temp up, first with a 40W bulb, then a 60W, and now a 75W. The RH inside the box has gone from 88% to it's current level of 78% over two weeks. The dehumidifier has accumulated about a pint of water, and there is a lot of rain out on the foil faced walls. I choose to use the dehumidifier and not put vent holes in so that my shop doesn't get exposed to all the moisture. Since this is my first experience with this, I'm not sure if the RH should be lower at this point (after 2 weeks). Is the rain out in the chamber "normal"? I know that people use old freezers and put vent holes in them, but I've also read of those who use an enclosed box without vents. I thought the dehumidifier would collect most of the moisture, but that doesn't seem to be the case. Any guidance with respect to RH levels, extent of rain out, etc. would be appreciated. Thanks.

[Kyle Iwamoto]

Edward,

I have no idea about the ideal RH, I don't remember reading of anyone measuring it, they just dry slow enough to avoid the wood disintegrating.

JKJ

I followed Cindy's design. I'm not smart enough to think of that. Gotta give credit where credit is due.
As far as ideal RH, I just watch it and when it stops going down I increase the bulb wattage. I have a cheap indoor/outdoor temperature (and RH) gadget to watch without having to open and close the door.

[Edward Weingarden]

John - thanks for directing me to Cindy's write-up. For the last 24 hrs, I left the door open a crack. The temp/RH this morning are 90 degrees and 50% (I also use an indoor/outdoor temp/RH monitor). For now, I'll continue with observations and adjustments throughout this experiment.

[Peter Blair]

Has anyone else tried a dimmer switch instead of changing the bulbs? I had no success with life of my light bulbs until I installed a dimmer. I now use a 100 watt bulb. Start out with it on low and go brighter as I need. Seems that the bulb lasts way longer.

[John K Jordan]

Has anyone else tried a dimmer switch instead of changing the bulbs? I had no success with life of my light bulbs until I installed a dimmer. I now use a 100 watt bulb. Start out with it on low and go brighter as I need. Seems that the bulb lasts way longer.

I used to do that all the time and it does indeed make the bulb last longer. In fact, you used to be able to buy a button to drop in the socket under the bulb base which acted like a dimmer and reduced the voltage enough to make incandescent bulbs last forever - haven't seen them in a long time. I have a maybe halogen desk lamps with dimmers, some in use for over 20 years, none have had burned out bulbs because I run them at least slightly dimmed, sometimes dimmed a lot.

What I started doing some years ago was buy 130v bulbs to use on our nominally 120v power. They, by nature, are a tiny and undetectable bit dimmer than 120v bulbs of the same wattage. However, this works the same way as a dimmer and extends the life of the bulb tremendously. Back when the gov here indicated incandescents would be phased out I bought a lifetime supply of 130v bulbs from 40 watts on up. Amazon.

Oh, another thing I used to do - write the date on the bulb and if it burned out before the promised time on the package I took it back for a replacement. Never got an argument. It did require saving the package and the receipt, a pain. Phillips from HomeDepot were the worst.

JKJ

[Brice Rogers]

I use some 60 or 75 watt bulbs in a "food" dryer or "urethane" dryer. The GE bulbs burned out fairly quickly. Or at least more quickly than I thought that they should. But the Dollar store incandescent bulbs seem to be more robust. I'm not sure how they are available after the US gov't law changes. But they work pretty good.

[John K Jordan]

I use some 60 or 75 watt bulbs in a "food" dryer or "urethane" dryer. The GE bulbs burned out fairly quickly. Or at least more quickly than I thought that they should. But the Dollar store incandescent bulbs seem to be more robust. I'm not sure how they are available after the US gov't law changes. But they work pretty good.

Be glad you don't buy bulbs in the middle of Mexico. I rewired some buildings at a missionary friend's camp for children in the central highlands of Mexico. Several times I purchased dozens of bulbs from a local place since the nearest alternative was a 5 hour drive. Almost always more than 50% of the bulbs would be burn out within one day.

Other electrical supplies were difficult or impossible to find. One circuit to a water heater used a 14-ga romex stretched 100' in an attic from a 50 amp breaker. It was two years before I could get back with the proper wiring and breakers.

If you can't find 130v bulbs, maybe try "rough service" or rough duty incandescent bulbs. I've had these last longer in high temperature/humidity conditions (poultry house, etc).

JKJ

[Peter Blair]

Thanks John. My issue is more about making what I have last as long as possible. When I heard about the pending ban on incandescent lamps I rushed out and bought a bunch. Now I'm trying to stretch them. You sure have had an interesting life by the sound of things compared to mine at least!!