Here’s a “rip the band-aid off”quick write up my approach to drying bowls using denatured alcohol.
If you have any experience with turning green lumber, you probably also have experience with throwing away bowls that have split or cracked beyond the point of repair. You may have also encountered a piece that has warped so much during the drying process that finish turning your bowl would be an exercise in futility.
To the rescue is a myriad of drying methods that are used by many turners to reach the same end result, dry roughed out bowls that aren’t cracked or overly warped!
Before I started using denatured alcohol (DNA) to dry bowls, I used paper bags with a handful of shavings in the bowl to slow down the drying process. My success was about 80/20. As I’ve gotten busier and begun turning wood that is more green, I’ve found that my bagging method was less and less effective. This spurred a search to increase my success rate with turning green wood. The two methods I was down to trying was boiling the wood or DNA soaking.
While I like fire as much as the next guy, I don’t have a great area to set up a propane turkey fryer to boil a large container of water for drying my bowls. In addition to that, I normally have to do my work in relatively short periods of time. I seldom have a full day or afternoon to dedicate to roughing out bowls and then boiling them.
The appeal of DNA soaking for me is that I can drop rough outs in the solution as I finish them up and can forget about them for a while until I either need to add more rough outs to the tub or remember to pull the currently soaking bowls out. For my larger tub of DNA, I wrap the top with plastic wrap to help seal the tub and prevent the alcohol from evaporating. This probably isn’t required, but it’s cheap insurance that doesn’t take long to apply.
Soaking Method:
- Put rough turned piece into DNA bath
- Leave it for at least 24 hours, longer for more green pieces (no real quantitative guidelines here…)
- Remove piece and pour excess back into tub
- Let dry for 15 – 30 minutes
- Wrap outside and rim of bowl only with paper
- Store bowls upside down allowing air to reach inside of bowl (sticker similarly to drying dimensional lumber)
- Piece can be finish turned as soon as two weeks after removal from Alcohol, but check moisture content if possible.
Who doesn’t love pictures to go along with instructions?
I wrap the bucket & lid to slow down the evaporation of alcohol.
I like to wear gloves while I’m taking bowls out or putting new bowls in the bucket. Also, having good air circulation is a plus so you’re not inhaling large amounts of alcohol fumes.
Let the bowls hang out for a while after allowing the majority of DNA to drip into the bucket. If I have 10 or more bowls at this stage I put them in the driveway so I’m not flooding the shop with fumes. It’s also not a bad idea to prop one side of the bowl so that air can fully circulate around the piece.
Place the bowl in a paper bag after about 30+ minutes of air drying. We save our paper bags from the grocery store which work great for this!
Now just wrap up the bowl as shown! Tear the bag as needed to fit the bowl.
You should be good to finish turn the bowl in a few weeks!
Supplies:
- 5 gallon bucket for pieces up to 10″ diameter
- 15 gallon tub for pieces up to 18″ diameter (found mine at Agri Supply)
- Denatured Alcohol
**The buckets listed above are similar to ones I used. The 15 gallon tub listed is for reference and does not have a lid; you will need to find a tub with a lid)
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Additional Information:
- David Smith has written a fair amount about DNA drying.
- AAW forum
Thanks for reading, I hope this helps out! Please feel free to leave comments or questions below!
Mike my concern is using denatured alcohol in the my basement where
I turn. Should i be concerned about pilot lights etc.
I’m at least 20 feet from the furnace and hot water tank
will these vapors travel?
ALTERNATIVE can i keep it in my cold winter shed ?
or will it freeze?
I just don’t want to blow the house up
any feedback?
joe
Hi Joe,
If it were me, I wouldn’t have a tub of denatured alcohol around pilot lights. I wrap the top of my container with cling wrap to help mitigate evaporation and I’ve never smelled the DNA unless I have the lid off.
In your situation, I’d be inclined to have your bucket of DNA in the shed. Alcohol doesn’t freeze until around -150 F depending on proof so I don’t think you should have a problem there.
Good luck, I hope the method works well for you!
Mike
Nice description. Thank you. I liked the photos that went with the report. Well done.
Any experience with and thoughts on microwave drying of rough-turned pieces? Thanks.
Hi Stephan,
I’m glad you like the post, I hope it’s helpful.
I’ve not used a microwave for drying pieces since most of my work won’t fit in a microwave. Also, not too sure how my wife would feel about me zapping a wet piece of wood in our kitchen unit 🙂 Check out the AAWforum.org on the subject.
Regards,
Mike
Followup question: why wrap in a paper bag? Wouldn’t it be better and simpler to let air circulate freely around the piece to evaporate DNA?
Hey Bill,
The reason for the paper bag is to bias the drying to the inside versus the outside. When a bowl dries it warps. The outside is under tension while the inside is under compression. Cracks won’t originate from the inside of a bowl, so leaving that uncovered dries the bowl as quickly as possible. Make sense?
Regards,
Mike
Thanks for the great post Mike. The question I have is how long does the DNA last before replacing and how do you know when to replace it?
That’s a tough one to answer. I seem to get a few months of putting lots of green roughed turnings in about 3-4 gallons of dna. Obviously there are tons of variables ranging from species to moisture content of the wood when rough turned to the size and wall thickness of your turnings.
My best test for when the dna needs replacing is based on how strong the smell is. I don’t recommend just sticking your head in the container and taking a whiff but you can get a good sense of things that way.
Hope that helps!
Nice post Mike. I enjoyed reading about the DNA drying process. I’m just starting out with turning and just recently got some nice green walnut, that my dad and I are going to turn into bowls, platters, and other items. I was wondering since the tree was just cut down in the month, should I allow the wood to sit longer prior to turning it into a bowl or something else? Which leads me to the next question is there a certain moisture content that I need in the wood before even considering the DNA drying process?
Nope, have at it!
Hi, my boyfriend and I turn. We have , pad auk and it doesn’t see to take the salad bowl or butcher block treatments. It stays tacky for weeks. I’ve heard you can use the denatured to remove some of the oils. Then add the finishes . It that safe?
Ok, this is about to be a slippery slope. When using exotics such as padauk you really don’t need a finish for salad bowls. To answer your question, yes you can you a solvent to temporarily “remove” the natural oils, but this is more appropriate for gluing exotics than finishing them. If it were me, I’d not finish them and let the natural oils protect the wood. Also, just a word of caution. Padauk dust is known to be quite problematic to some folks. I had a friend that had to be rushed to the ER after working with it because he had a reaction to the dust. This could happen with any material really, but is a bit more common with some exotics. (Sorry for the tangent) I hope that helps!
Wow, I had no idea.. (Newbie), so a quick wash with NO sealer, just sanding and it’s a salad bowl..
We love this wood and Purple, red, yellow Heart. Is there a book you would recommend to us on this topic and finishing them ( well besides your self and abundance of knowledge)…
You could always just add some bees wax if you wanted something on our, but really not necessary. When I was early on in woodworking, the woodworkers encyclopedia was given to me. It’s been a good book to reference! Feel free to ask questions anytime!
I would love to use this process for drying green log slices. Should I wrap the whole log slice with a paper bag?
Hi Mary,
Generally drying slices like your describing (aka cookies), unless they’re small in diameter, is nearly impossible to prevent the piece from splitting due to grain orientation and the way wood moves during seasonal changes. You’ll almost always end up with some cracking. Regardless, if you wanted to dry slices with denatured alcohol, yes I’d wrap the whole thing. Just be sure to turn the bag inside out or change the bag occasionally in an effort to mitigate mold growth.
Hope that helps!
Regards,
Mike
Have you compared DNA with Pentacryl? Results?
Hi Bill,
No I haven’t. If you try both of these methods I’d be interested to hear what you’ve found. Thanks!
Just wonder if you have noticed a colour change using either the DNA or when boiling?
I am going to start drying my green pieces and specifically love the natural wood colour.
Hi Rob,
I have not noticed any appreciable color change once the piece is dried from soaking in DNA. I do not have any experience with boiling pieces so unfortunately I cannot offer any information on that topic. Cheers!
Hi Mike,
I found your DNA advice very useful, I’ve been drying my wood in a shed at a very slow rate, so will definitely try your method. I’ve turned lots of bowls with varying success. Depends on the wood obviously. My question, was after turning the wood what finish did you apply to it? I’ve been using blonde dewaxed shellac , mixed with DNA. What would you recommend. Many Thanks Mark
Hey Mark, I usually finish with straight walnut oil or a Danish oil.
Mark, I have an old pressure pot from a painting rig. Plenty big enough for a couple of 8″ bowls. Do you think soaking them overnight in such a pot at say 20 PSIG would facilitate the complete absorption of the alcohol? Such things on a much larger scale are used here in Miami to “pressure treat” lumber…
I don’t see why it wouldn’t work. That said, from what I’ve researched the pressure wouldn’t be needed as alcohol displaces the water rather quickly. Let me know how it works out though!
Regards,
Mike
You’d want to be very careful putting alcohol under pressure- that is essentially a bomb.
Mike,
I just found your write up on using dna method and, I found it good information and love seeing pictures. I’m a “show me” type of turner. I have been using a lot of kiln dried wood because I hated the long wait of drying green wood. Recently starting turning green and, found out I loved it! My question with the dna alcohol is, after all the soaking of the bowl, is there anything to worry about it being not food safe afterwards? I finish my bowls with either danish oil, shellac, or salad bowl finish, which I know after cure, they are safe.
Hey Tony,
As long as the DNA is fully evaporated you’ll be fine in term of the bowl being food safe. For what it’s worth, DNA is in most blended finishes such as danish oil and shellac.
Cheers,
Mike
thanks for the info about DNA. i’m trying to find all the ways I can to use green wood.
You’re very welcome! Have fun!
have you ever tried using DNA with a vacuum pot
Nope I haven’t. I think someone else asked about that on here a while back though…
Don’t you have problems with the wood floating in the DNA? I don’t see any type of weights in the photos to prevent floating. So I’m curious?
Hi Charles, yes the do float. However the DNA really gets through all the grain through capillary action. The pieces have always been soaked on all sides when I take them out of the tub, and they’ve dried evenly without cracking. That said, you could certainly put some weight on them to hold it down.
Regards,
Mike
do you think that this approach can be scaled up to handle wood slabs that are to be used for table tops?
Hi Dave,
You could absolutely use this approach for drying slabs. Using DNA would help to prevent the slabs from twisting or checking during the drying process. Let me know if you give this a try!
Regards,
Mike