Drying huge roughed blanks, using DNA

[dirk martin]

I'm told that if I'm going to rough out some large blanks (20 - 28 inches in diameter) that I should leave the walls a good 2" thick as it dries.

I plan on trying the Denatured Alcohol method for drying.

Anyone have any experience if DNA will work on 2" thick roughed blanks?
How long do I let 2" material soak? Overnight good enough?

[Scott Hackler]

2" to 2 1/2" would be fine for the roughout for most woods. From my experience Oak and Hackberry needs a little more because they always oval on me. As far as the Dna, softer open grain wood would be fine for an overnight soak, but I would soak a really thick hard wood bowl for a few days. I also triple newspaper wrap after the Dna bath and poke vent holes in the opening of the blank for the drying process.

[David E Keller]

I use the '10% of diameter' rule for determining wall thickness of roughouts... Never turned anything that big, so I can't be too specific about soaking times, etc.

[Steve Vaughan]

I'd agree with Scott, I think you'd be fine at the 2 or 21/2 and an overnight soak. I've seen others on here mention that they'd left stuff in for longer with no adverse affect and I've left stuff soaking for several days myself. I don't think too long is much of a concern. And the wood type will make quite a difference too with the oval-ing. I had some small roughed out bowls of gum and they oval-ed really bad...it was a really good thing I left them a bit heavy.

[Bernie Weishapl]

I use the DNA method on some pieces if I am in a hurry. I leave fruit wood 5 to 6 days. Big pieces thicker than 1" I still soak 5 to 6 days. I feel overnight is definitely is not enough soak time. If you are not in a hurry I coat the whole bowl with anchorseal, store in a cool dry place with not much air movement and on the floor.

[Nathan Hawkes]

I really don't have any experience with this, but it sure sounds like a recipe for disaster. Trying to dry out something quickly which is that thick is going to create some amazing stresses on the wood. I hope it works well for you. Please keep us informed!

[Reed Gray]

Check out this guy. I met him at a show in Seattle, and he turns big a lot. Seems like most of his were green turned to final thickness and allowed to warp. I really liked his stuff. Contact him, he might talk to you.

http://www.vkleibrant.com/

robo hippy

[Jim Burr]

Although mine aren't big, like Bernie I use a lot of fruit wood. I have no problem leaving it in DNA for 2 weeks to ensure all "water" is displaced. Since the alcohol is a muck lower specific gravity, it will displace/evaporate must faster so the multiple paper wrap is a great idea. So far, it's worked on apricot, peach, walnut, pistachio and grape...still working on almond

[dirk martin]

Trouble is, I am in a hurry for these to dry. I've got dozens and dozens to turn....if not hundreds. So, I'm searching for the fastest way to get these dry, and thus far the DNA method sounds like the quickest.

[Reed Gray]

If you are in a hurry, there are a couple of things you might do, but would require money. You could boil them. This ruptures the cell walls, and allows the entrained water (stuff on a molecular level) to get out more easily, and stabilizes, or at least releases a lot of tension in the wood.

If you have a large micro wave, it can be done that way.

You may want a solar kiln.

You may want a vacuum kiln.

You may want a light bulb convection kiln (most of the time done with an old freezer. A dehumidifier kiln is similar.

Other than the above, you have to wait, which actually gives you more time to turn. If you will have on going demand, then eventually you will get your stock rotation to the point where there is always some thing to turn green, some thing drying, and some thing ready to finish turn. The kilns will speed up the drying process, but you will have to experiment to find out what works. Of course, it can be a lot different for each different species of wood you are trying to dry. If you dry too fast, it cracks, if you dry it too slow, it molds.

The one advantage to green turning is that a 3/8 inch thick bowl will dry in my shop in about 2 weeks. Customers seem to like the 'organic' oval shapes.

robo hippy

[Scott Hackler]

Dirk, your in a catch 22. If you speed it up too much your going to get cracks and extreme warp. The DNA method, for me (in Kansas' climate), works better than any other method I have tried. I have done: roughed and in a paper bag, roughed and stuffed with shavings in a paper bag, left out on the floor, anchor sealed and wait for 6-8 months.

The Dna method, for me, drys a roughed out _____ in 2-6 weeks, most of the time variables are with the different wood varieties and the form. A hollow form takes longer for me to dry than a open bowl.

FYI

Trouble is, I am in a hurry for these to dry. I've got dozens and dozens to turn....if not hundreds. So, I'm searching for the fastest way to get these dry, and thus far the DNA method sounds like the quickest.

[Kim Ford]

Dirk;

I have done a good amount of research on this and would suggest you look into a vacuum kiln. Look on internet and you will find some very useful information. They are not cheap, to buy or build, but my research indicates that they will dry up to 2" wood very efficently in 3-4 days.

I bought a vacuum pump and am in the process of building a vacuum chamber that will take two bowls up to 24" in diameter, but am not there yet. In addition to the pump and the chamber you need to have a contact source of heat as well and a moisture seperator. Most commercial units use heat strips, the wood needs to be brought up to about 95 degrees F.

Commerical units are available but pricey. I know of a person in the flat stock hardwood business who has one and he says that they work very well and produce excellent results up to 8/4 stock.

Hope this helps.

Kim

[dirk martin]

Reed....why do you omit the option of DNA drying?
From my research, that seems to be the fastest, with least warpage, cracking, and other degradation.

Scott, I fully agree.

Kim, aren't vaccuum drying methods for flat stock, not bowls? I doubt a vacuum kiln will handle my blanks, which start out 10 - 15 inches thick...sometimes more.

[Kim Ford]

Kim, aren't vaccuum drying methods for flat stock, not bowls? I doubt a vacuum kiln will handle my blanks, which start out 10 - 15 inches thick...sometimes more.

Dirk; they go in the kiln after they are roughed out, so your thickness in 2" +/-. Maybe this will help.

http://www.svwoodturners.org/Newslet...06/10-2006.pdf

[Reed Gray]

I have used lumber from vacuum kilns, and it is super. 8/4 boards were dried in 7 to 9 days. Temps were up to 120 or so. Wood worked like air dried as in you rip a board on the table saw, and you get shavings, not dust. Same with a solar kiln.

robo hippy