Food dehydrator for bowl blanks?

[Dueane Hicks]

I've been watching the wood whirler on YouTube. He seems to have something going with a food dehydrator. I found nice blanks at a good price, but they are cut green then waxed. I'd like to find some way to get the moisture down, without waiting till I'm dead to make something out of them. Have any of you experimented with a food dehydrator?

[John K Jordan]

I've been watching the wood whirler on YouTube. He seems to have something going with a food dehydrator. I found nice blanks at a good price, but they are cut green then waxed. I'd like to find some way to get the moisture down, without waiting till I'm dead to make something out of them. Have any of you experimented with a food dehydrator?

I have not experimented with using a food dehydrator for drying wood blanks or heard of this from other turners. (I prefer to air dry wood.)

Maybe describe your blanks. Do you mean you want to dry a complete, unturned blank such as a section of logs? How large? What species? (Some species are more stable than others)
Or are these blanks cut from logs or rough-turned in a way they can be dried successfully?

I process and dry a lot of wood. Due to the nature of the structure of wood drying a large solid blank can be tricky.

JKJ.

[Chris A Lawrence]

While his experiment may have merit to me its flawed. When he removed the 3/4" thick bowl out of the dehydrator he tested the moisture with a meter within 10 seconds and called it dry. Those meters only read as deep as you can jam the pins in the wood. The surface of that bowl was dry but who knows if the center was without letting it sit for awhile and retesting it. Like John said give us the dimensions and type of wood the blanks are made out of and someone can give you ideas of how to dry them successfully.

[Kyle Iwamoto]

Just my $0.02, I would not do anything with the blank. I much prefer to turn green/wet wood, it cuts easier, less dust in the air, lots of reasons. The downside is I have to twice or three times turn everything....... Oh, if you turn it green, you avoid the possibility of a crack that could ruin the whole blank, downside, if it cracks when whole, chances are that it may crack after or during roughing.

However, the original question is very good, I do wonder about that. I have a fridge kiln (Google Cindy Drozda fridge kiln) and am very happy. Cost me around 50 bucks total. Drying roughs in the fridge kiln takes 3 or 4 weeks. I would like to know how fast/slow a dehydrator can dry roughed bowls...... Got some rather large and pricey dehydrators out there.

[John K Jordan]

...However, the original question is very good, I do wonder about that. I have a fridge kiln (Google Cindy Drozda fridge kiln) and am very happy. Cost me around 50 bucks total. Drying roughs in the fridge kiln takes 3 or 4 weeks. I would like to know how fast/slow a dehydrator can dry roughed bowls...... Got some rather large and pricey dehydrators out there.

I still want to know if when the OP said "I found nice blanks at a good price, but they are cut green then waxed." is he talking about drying solid, unturned green blocks of wood or drying roughed-out bowls/platters/boxes. Big difference!

JKJ

[Dueane Hicks]

I have not experimented with using a food dehydrator for drying wood blanks or heard of this from other turners. (I prefer to air dry wood.)

Maybe describe your blanks. Do you mean you want to dry a complete, unturned blank such as a section of logs? How large? What species? (Some species are more stable than others)
Or are these blanks cut from logs or rough-turned in a way they can be dried successfully?

I process and dry a lot of wood. Due to the nature of the structure of wood drying a large solid blank can be tricky.

JKJ.




It is 12x12x4 of ambrosia maple. Moisture is 18%. I tried rough turning it and already got a crack. I put it in a bag of shavings from hollowing it out. They completely coated it with heavy wax. I'm guessing covered with wax, it will never dry out?

[Chris A Lawrence]

Something like that i rough turn to 3/4 inch then coat in anchor seal and let it sit for 4 months or so. 18% is not super wet some fresh cut pieces i turn are in the 30% range. Craft supply sells artisan woodsealer that works just as well as anchor seal but is cheaper. They have free shipping right now until 12/13.

[Bill Jobe]

Have you considered using a microwave oven?

[Karl Loeblein]

I suspect a food dehydrator would dry the outside of your wood too quickly. A large moisture differential between the outside and inside of a piece will often cause cracking. This is the reason why many commercial kiln operators add moisture back to a stack of wood in order to lessen losses due to moisture differential. I think you'd be better off using a small fridge/freezer/dishwasher kiln where you can control moisture loss (by turning down heat or blocking exhaust holes as needed).

Some other alternatives are first cleaning off any coatings/wax/ and then soaking the piece in DNA (De-Natured Alcohol), Dish Washing Soap, or Boiling Water. If you're in a hurry then a microwave can be used, but you might still need to lessen moisture differential by covering item with saran wrap that's slowly pulled back as the item gets dryer.

[John K Jordan]

It is 12x12x4 of ambrosia maple. Moisture is 18%. I tried rough turning it and already got a crack. I put it in a bag of shavings from hollowing it out. They completely coated it with heavy wax. I'm guessing covered with wax, it will never dry out?

Water vapor goes right through wax. A blank waxed all over will still eventually dry out, but slower than unwaxed. It can crack just as much as an unwaxed blank depending on the wood species, and whether pith, juvenile wood, or sap wood is present, how the grain is oriented on the various faces, the temperature/humidity in the environment, etc.

Waxing the wood properly does slow down the shrinkage which can minimize the cracks. Typically the end grain is coated with wax and the side grain is uncoated. Since water exits the end grain at a much high rate than the side grain, the wood right at the end grain surface can quickly get too dry and shrink too much due to the strong moisture gradient - the cells are literally pulled apart by the strong force of shrinking. Once such a crack/check starts at the surface, it only gets worse. Waxing the end grain slows down the drying at the surface and gives the moisture deep in the wood more time to migrate towards the end grain which creates a less severe moisture gradient and less chance of the strong tangential shrinkage pulling the fibers apart. The thicker the wax the better! When I use Anchorseal I usually decant some into a separate container (a plastic coffee can) and leave it open to the air for a couple of days so it gets thicker and goes on thicker.

The wood should be sealed as soon as possible after felling the tree or cutting up the log. If you wait until a check or crack already starts, even if it's so small it's invisible, it's too late. Best thing to do with an unwaxed or cracked blank is to cut the crack away then cut thin slices off the end grain until bending one doesn't separate easily. This proves you've cut deep enough. When I process logs into turning blanks I wax the end grain immediately, then check the blank in a few days. If any cracks have developed I cut them away, rewax, and check again after another few days. (Sometimes I end up with a considerably smaller blank but that's far better than a cracked blank!)

I've successfully dried that size of ambrosia soft maple by waxing just the end grain and air drying on shelves in the back room of my shop which I don't heat as much in the winter. But it depends on the wood - some will crack regardless of what you do, some is better. I have a block of 12x12x15" ambrosia maple drying for about 4 years now with no sign of a crack. On the other hand, I had a 3x3 block of maple split nearly in two! I usually have very little trouble with walnut blanks but recently one 4" thick blank developed a 1/2" deep crack all the way down the sapwood side. I cut this off, rewaxed and the next day it had 1/4" deep crack in the same place. I cut of some more and now the blank is down to about 3" and so far, no cracks. (keeping fingers crossed.)

When I rough turned bowls, I would always wax the end grain inside and out and sometimes wax the entire roughed bowl. I air dried on wire shelves for several months before finish turning.

BTW, there are several ways to preserve wet unturned blanks until you are ready to work on them. One is called "ponding" - immerse the blank completely in clear water, weighting it to hold it down. Change the water as needed. Wood will keep indefinitely this way. Another way is to wrap in plastic and freeze it. Another way is to boil it, discussed in detail recently in another thread.

BTW, I have some blanks that I cut from trees in 2006 and earlier. I try to process some wood every few months so I'll have a continuous supply of dry wood. (I far prefer turning dry wood to green.) I do make some bowl blanks, but mostly blanks for spindles, boxes, and other generally smaller things.

Freshly cut chunks ready to process, mostly cherry:
421456

Directly from the sawmill behind the barn:
421453 421459

This guy's ready to go rough out some bowls:
421460

Processing on shop bandsaw
421458

Some ambrosia maple ready to put on drying shelves:
421457

Some drying on wire shelves:
421454 421455

JKJ

[Bill Jobe]

From live standing OO tree, ends coated with anchorseal, got home, cut almost a 3" slab from the very base of the tree, microwaved it a long, long time, then sanded it and varnished it.

I want to strip it, sand the brown down to yellow, then seal it with several coats of Epiphanes. Hopefully I can extend the yellow considerably using their Marine spar varnish.

[Dueane Hicks]

I tried two times at 50% power for 2 minutes each time letting it cool. Got a one inch crack in the side of the bowl.

[Dueane Hicks]

Water vapor goes right through wax. A blank waxed all over will still eventually dry out, but slower than unwaxed. It can crack just as much as an unwaxed blank depending on the wood species, and whether pith, juvenile wood, or sap wood is present, how the grain is oriented on the various faces, the temperature/humidity in the environment, etc.

Waxing the wood properly does slow down the shrinkage which can minimize the cracks. Typically the end grain is coated with wax and the side grain is uncoated. Since water exits the end grain at a much high rate than the side grain, the wood right at the end grain surface can quickly get too dry and shrink too much due to the strong moisture gradient - the cells are literally pulled apart by the strong force of shrinking. Once such a crack/check starts at the surface, it only gets worse. Waxing the end grain slows down the drying at the surface and gives the moisture deep in the wood more time to migrate towards the end grain which creates a less severe moisture gradient and less chance of the strong tangential shrinkage pulling the fibers apart. The thicker the wax the better! When I use Anchorseal I usually decant some into a separate container (a plastic coffee can) and leave it open to the air for a couple of days so it gets thicker and goes on thicker.

The wood should be sealed as soon as possible after felling the tree or cutting up the log. If you wait until a check or crack already starts, even if it's so small it's invisible, it's too late. Best thing to do with an unwaxed or cracked blank is to cut the crack away then cut thin slices off the end grain until bending one doesn't separate easily. This proves you've cut deep enough. When I process logs into turning blanks I wax the end grain immediately, then check the blank in a few days. If any cracks have developed I cut them away, rewax, and check again after another few days. (Sometimes I end up with a considerably smaller blank but that's far better than a cracked blank!)

I've successfully dried that size of ambrosia soft maple by waxing just the end grain and air drying on shelves in the back room of my shop which I don't heat as much in the winter. But it depends on the wood - some will crack regardless of what you do, some is better. I have a block of 12x12x15" ambrosia maple drying for about 4 years now with no sign of a crack. On the other hand, I had a 3x3 block of maple split nearly in two! I usually have very little trouble with walnut blanks but recently one 4" thick blank developed a 1/2" deep crack all the way down the sapwood side. I cut this off, rewaxed and the next day it had 1/4" deep crack in the same place. I cut of some more and now the blank is down to about 3" and so far, no cracks. (keeping fingers crossed.)

When I rough turned bowls, I would always wax the end grain inside and out and sometimes wax the entire roughed bowl. I air dried on wire shelves for several months before finish turning.

BTW, there are several ways to preserve wet unturned blanks until you are ready to work on them. One is called "ponding" - immerse the blank completely in clear water, weighting it to hold it down. Change the water as needed. Wood will keep indefinitely this way. Another way is to wrap in plastic and freeze it. Another way is to boil it, discussed in detail recently in another thread.

BTW, I have some blanks that I cut from trees in 2006 and earlier. I try to process some wood every few months so I'll have a continuous supply of dry wood. (I far prefer turning dry wood to green.) I do make some bowl blanks, but mostly blanks for spindles, boxes, and other generally smaller things.

Freshly cut chunks ready to process, mostly cherry:
421456

Directly from the sawmill behind the barn:
421453 421459

This guy's ready to go rough out some bowls:
421460

Processing on shop bandsaw
421458

Some ambrosia maple ready to put on drying shelves:
421457

Some drying on wire shelves:
421454 421455

JKJ


Wow, very informative! I wish my health would allow me to get out and find wood, then process it myself! I live in the Olympic mountains and there are wood piles up where they clear cut, then leave the stumps in a giant pile. Mostly fir,hemlock,maple,some cedar.

[Bill Jobe]

I tried two times at 50% power for 2 minutes each time letting it cool. Got a one inch crack in the side of the bowl.

Not much time in the microwave.
50% simply means it will run half of the time on full power.
Might have been the heating and the cooling off caused the crack. If the slab I dried was still very hot after running the micro a couple of minutes, I'd stick it right back in without letting it cool. I knew if it was very hot that it still had high moisture.
But, perhaps my one and only try with a microwave was "beginner's luck"?

[Kyle Iwamoto]

Seems that the food dehydrator may not be s cost wise investment? They have small cheap ones and large pricey ones. Fridge kiln is the way to go IMO. Just my $0.02.
I did try the micro, it does work, but don't use "yours". Buy a new one and give that to the wife and use the old one...... I did 1 min and wait a pretty long while to let the wood really cool to ambient. I put the item is an open ziplock with a paper towel to soak up the vapors.

[Mike Nathal]

From live standing OO tree, ends coated with anchorseal, got home, cut almost a 3" slab from the very base of the tree, microwaved it a long, long time, then sanded it and varnished it.

I want to strip it, sand the brown down to yellow, then seal it with several coats of Epiphanes. Hopefully I can extend the yellow considerably using their Marine spar varnish.


In my experience you cannot prevent Osage Orange from turning brown, no matter what you put on the surface. (Short of keeping it in your basement out of the sun.)

For another option consider bleaching. It turns the OO an unusual, pleasing shade of grey.

[Bill Jobe]

It's very pleasing to the senses to take a chainsaw to OO and watch that beautiful yellow reveal itself.

[Brice Rogers]

I built a food dehydrator - - initially to dry apple, plum, orange slices. It was easy to build. Just a plywood box with two light bulb receptacles, slats to slide in replacement window screens, an automobile air cleaner filter and a small 120 volt computer/electronic fan.

I haven't used it recently to make dehydrated apple slices. But I occasionally use it to speed up the drying/curing time of wood turnings with multiple coats of polyurethane. It works well for that.

To minimize cracking I try to slow down the rate of drying with wood and try to minimize big differences in humidity. I find that the most cracking occurs when the inside is wet and the outside dries to fast. But I suppose that if I waited until a piece was "semi-dry" that I could safely put the wood into the dehydrator.

But, I find that I have built up a whole bunch of blanks. Several are 2 or 3 years old. When I first started turning, I had 2 or 3 pieces of wet wood and was in a hurry. Perhaps that is the situation with the original poster. But after several years of turning I now have perhaps 50 to 75 blanks and about 80% are bone dry. I write the weight on the pieces in pencil so I can figure out if the wood is done drying or not.

[Bill Jobe]

Mike, doesn't Epiphanes protect OO from uv like any other wood or is there something else about the wood that it cannot be protected from uv at all?

[John K Jordan]

Mike, doesn't Epiphanes protect OO from uv like any other wood or is there something else about the wood that it cannot be protected from uv at all?

I think I mentioned here (or in another thread) that opinions vary on exactly what causes color change. Some say light only, some say oxidation plays a part. My simple experiments with purple heart long time ago seemed to point to both. This was not an exhaustive scientific study.

Depending on how interested you are I suggest an experiment. Prepare several identical strips of freshly exposed osage in the form of some flat sticks. Put various finishes in bands on the strips, including the Epiphanes you mention (don't know what that is but it doesn't matter.) Leave a patch of unfinished wood on each strip for a control. Keep one in the sunlight, put one in the dark.

To test for oxidation, seal two in strips prepared the same way in two glass jars with nitrogen or argon gas and put one in the sun and one in the dark. For extra credit seal two in two glass jars filled with 100% oxygen and put one in the sun and one in the dark. Compare them after some time. For even more fun, prepare additional samples and keep them under incandescent, fluorescent, and LED lighting. A huge number of variations are possible, for example different temperatures, different woods (purpleheart padauk, etc). Keep careful notes. Write a magazine article.

The top side of my small purpleheart samples showed color change on a relatively dark shelf in the corner of my garage after six months or so. There was definitely no sunlight in that corner. The bottom side, sitting undisturbed directly on the shelf, showed very little color change.

JKJ