DNA - Why

[George Babij]

Hello All, Reading some of the threads, I see people soaking their projects in DNA for varied lengths of time.
Can someone explain Why? Do you soak Green wood? What is the principle behind this method?
Always looking for new ways to do things.
Thanks in Advance
George:)

[Vilas Schroeder]

The purpose of this process is for the DNA to draw out the moisture and speed up the drying process. I'm sure more experienced members can give a more detailed reply.

[Jim Heikes]

This is totally plagiarized.....but several articles I've read recently expound the same message:


" Some incorrect assumptions are being made by those who believe that ethanol accelerates the drying process to any significant extent. A more accurate description of the mechanism is that the alcohol helps to soften the lignin enough to relieve some of the stresses that develop as water leaves the wood and it begins to shrink. Back in the early 20th century, there were several patents granted that involved using alcohol to accelerate the time to market when processing dimension lumber. None of the alcohol treatment methods proved to be commercially competitive with kiln drying. The claims that the patents were based on did not include faster drying. Instead, they were based on a method to stabilize the wood against things like checking, twisting, bowing, winding, and shake. The idea was to deliver stable wood more quickly to the customer regardless of its MC. Once it was stable, then it could air dry at the lumber yard"

That all said I soak in DNA for at least 24 hours and it seems to lessen or eliminate checking, cracking, twisting, etc.

[David T gray]

removes water and replaces with dna fast drying 2-4 weeks to dry a bowl of large size minimal movement, down side non really besides your wallet.

[Cody Colston]

George,

I don't know exactly how it works, but I do know that DNA soaking helps to keep the wood from cracking while it dries.

The basic method is to rough-turn a green blank, leaving the wall thickness 10% of the vessel diameter. Soak the rough-turned blank in denatured alcohol anywhere from 2 hours to overnight. Remove the blank from the DNA, let it drip dry and then wrap with brown paper. Remove the paper from the vessel opening and store it open to the air. After 3-4 weeks, the piece will be dry enough to finish turn. It will have warped, but cracking is greatly reduced or eliminated.

[Bernie Weishapl]

Cody pretty much described how I use DNA. I soak my pieces from 1 day to 5 days depending on the wood. Fruit wood gets a longer bath. I have experimented and now use anchorseal to seal the whole piece. I sit it on the floor or no higher than 2 ft off the floor with temps around 65 to 68 deg and little air flow to dry. It will take 8 months to a year but I have enough stock now that when I rough out 4 or 5 bowls I can return 3 or 4 to the lathe to finish. Talked with Mike Mahoney at a demo and he explained this is how he has done it for a long time. So far none of the bowls with anchorseal has cracked. Warped, yes.

[Dan Hintz]

Some incorrect assumptions are being made by those who believe that ethanol accelerates the drying process to any significant extent. A more accurate description of the mechanism is that the alcohol helps to soften the lignin enough to relieve some of the stresses that develop as water leaves the wood and it begins to shrink.
This description doesn't follow for me. During normal processing, wood takes years to dry... but an alcohol-soaked chunk will be at room humidity levels within a few weeks. Air-dried and alco-dried pieces from the same tree also appear to deform by similar amounts. Lignin softening may be a side benefit, but it doesn't appear to be a major effect. I'll have to think on it some more, but I question the validity of cell wall softening happening at all via alcohol... heating the water contained within the cell wall, yes, but not alcohol.

[Jim Burr]

Hey George, It's just a displacement method. Since DNA has a higher specific gravity than water, it moves from an are of higher concentration to an area of lower concentration...kinda like gas floating on water. The method is also used my Marine archeologists for preserving stuff like coin bundles, cannons, timbers and the like until the can be cleaned. Since water has 2 oxygen molecules, it can oxide...DNA, a derivative of ETOH has only 1 oxygen molecule and can't oxidize. For wood…as long as it has a roughly equal shape to diffuse from...DNA should move evenly leaving nice happy walls. One thing to add is the addition of newspaper or wood shavings for the inside to help that large airspace.

[David E Keller]

" None of the alcohol treatment methods proved to be commercially competitive with kiln drying"

This may be true, but I do think it's faster than air drying my turnings. I'm not sure about the checking factor... If I don't take precautions with DNA soaked roughouts, it seems that they are more prone to checking than non-soaked items. I suppose location, temperature, humidity all play a role ...

[Lee Koepke]

granted, I have a CHEAP moisture meter, but it takes close to half the moisture content from the soaking ... just a rough calculation, but the last piece I soaked went in almost 40% and came out 20% ish .. one random, non-scientific sample from a rookie .... take it for what its worth!

[Leo Van Der Loo]

Look if drying with alcohol was faster and dependable, than why are the big lumber companies not using this treatment ??, they are still using a lot of energy and time to dry their wood for the simple reason that alcohol drying doesn't work better or faster, it would be so simple to be able to stick the lumber in the big vats with alcohol, the same kind that they also use for pressure treating wood, being able to use and reuse many many times the same alcohol as the alcy dryer believers do, it would be so much less costly, you just take a guess why they do not use alcohol.

Drying rough turned wood doesn't take any longer than with alcohol IMO, and neither does it split more or less, but believing does some wonderful things for some people, the lame will walk and the blind see again ???

[David E Keller]

Look if drying with alcohol was faster and dependable, than why are the big lumber companies not using this treatment ??...

Because they're not drying spherical roughouts?:p:D

[Ralph Lindberg]

This is totally plagiarized.....but several articles I've read recently expound the same message:
.....

Jim, this closely matches a discussion I had on with a PhD (Forestry) on the subject with a a few years ago. He expounded that not only was it (for their needs) not commercially viable, it was also unpredictable. Unpredictable in that 8 hrs of soak would work for one sample of Walnut, another sample, even with the same RH, might require a different result. For completely unknown reasons.
The way Turners handle this unpredictability is to just leave the wood for a much longer time.

There is a Texas A&M (? I think) report on using DNA, as one step in stabilizing wood taken from under-water

[Jon Nuckles]

If a significant amount of the water comes out of the wood during the DNA soak -- 50% if it reduced moisture content in the wood from 40% to 20% during the soaking -- the water must be left in the container with the DNA, right? Has anybody seen any studies that look at how much water is in the DNA after the soak? It would not evaporate as quickly as the DNA, so I'd think the DNA in the soaking bucket would get diluted pretty fast. Any experience on how much wood a person can soak before having to replace the DNA? I want to believe, as I am a person with very limited patience.

[Dan Hintz]

Drying rough turned wood doesn't take any longer than with alcohol IMO, and neither does it split more or less, but believing does some wonderful things for some people, the lame will walk and the blind see again ???
Leo,

Are you saying a rough-turned green bowl left to dry will do so just as fast as one that was alco-soaked?

[Lee Koepke]

If a significant amount of the water comes out of the wood during the DNA soak -- 50% if it reduced moisture content in the wood from 40% to 20% during the soaking -- the water must be left in the container with the DNA, right? Has anybody seen any studies that look at how much water is in the DNA after the soak? It would not evaporate as quickly as the DNA, so I'd think the DNA in the soaking bucket would get diluted pretty fast. Any experience on how much wood a person can soak before having to replace the DNA? I want to believe, as I am a person with very limited patience.
what I have read is the (without being scientific) water 'attaches' itself to the alcohol molecules, so when you pull the bowl from the soak and the alcohol evaporates, it takes the water with it. The alcohol doesnt displace the water, nor does it come out or dissolve IN the dna.

[George Babij]

Thanks for all the replies guys. Certainly Food for Thought. I think I may get some DNA and give it a shot, if I can find some locally. My problem with drying wood is not having a suitable location to do so. A friend is also in the same boat, so we are considering/researching building a small Kiln.
Thanks again
George

[Leo Van Der Loo]

That is right, Fred Holder who was a believer in the process, and he was going to prove that the alcy bowls did dry faster, did a study with quite a bunch of bowls, same wood same shape all as similar as he could make them.

His findings in short, (weighted every day) the alcohol soaked bowls lost more weight the first few days, but it took just as long to get them to dry to the point they didn't loose weight anymore as the ones that did not get soaked in the alcohol.

[Ralph Lindberg]

granted, I have a CHEAP moisture meter, but it takes close to half the moisture content from the soaking ... just a rough calculation, but the last piece I soaked went in almost 40% and came out 20% ish .. one random, non-scientific sample from a rookie .... take it for what its worth!

Lee, you are aware that the meter is only telling you about the surface, maybe 1/8 of an inch of the wood, right? The only way to check the inside of the blank is cut it open (ya right) or weigh it.

Harbor Freight has some quite cheap electronic scales, they work very well for weighing.

[Ralph Lindberg]

That is right, Fred Holder who was a believer in the process, and he was going to prove that the alcy bowls did dry faster, did a study with quite a bunch of bowls, same wood same shape all as similar as he could make them.

His findings in short, (weighted every day) the alcohol soaked bowls lost more weight the first few days, but it took just as long to get them to dry to the point they didn't loose weight anymore as the ones that did not get soaked in the alcohol.

Leo, I was just going to relate Fred's study.
There have been others that found different results, this is part of why the industry doesn't use the method, it's unpredictable.

[Lee Koepke]

Lee, you are aware that the meter is only telling you about the surface, maybe 1/8 of an inch of the wood, right? The only way to check the inside of the blank is cut it open (ya right) or weigh it.

Harbor Freight has some quite cheap electronic scales, they work very well for weighing.
good point....

it probably won't matter as much once I get a stockpile of roughs done!

[Ken Whitney]

DNA! Them's fightin' words:)

Water and alcohol are different molecules. Water is very polar (i.e. water sticks to itself and to charged surfaces). Even though alcohol is a "bigger" molecule it is less polar and has a lower boiling point. There is no alcohol transport by water. Each moves relatively independently such that if you pour water into a glass and then pour in alcohol (i.e. scotch and water) they mix.

In a DNA soak, if the water concentration outside the wood is lower than inside the wood, water will flow out. If the alcohol concentration is higher outside the wood than inside, alcohol will flow into the wood. These process will continue until the concentration of alcohol and water are more or less the same outside and inside the wood, given enough time.

Now what effect this has on wood drying isn't really known. I suspect that evaporating alcohol out of the wood occurs faster, with less stress on the wood, than water evaporating from the wood. And this, alone, could account for the good results that some (me included) experience. The potential effect of alcohol on lignan is interesting, but I doubt that a relatively short term soak would substantially change the properties of lignan (although boiling probably does).

I don't think there is any experimental evidence one way or the other on this, and I suspect that we all try things until we hit upon something that works and then stick with it. And defend that method to the end!

Wood is very complex stuff. It's properties vary from species to species, from where and how it is cut from the tree, trunk wood, limb wood, crotch wood, etc. And when we turn bowls and vessels we are setting up differential stresses in the resulting roughed out form. The same rate of water loss produces very different movements on the inside of a bowl versus the outside of a bowl, for example, simply because of the geometry of the curved surfaces.

My name is Ken and I use DNA! The reason I do is that other methods have not worked for me, and I have the cracked bowls to prove it. I envy those of you who can stuff a roughed out bowl in a bag, throw in a handful of shavings, and call it good. I can't. I have to use $15 a gallon alcohol to get acceptable bowl blanks.

Ken

[Steve Schlumpf]

I very seldom comment on these type threads because of the polarizing effects it has between true believers and the heretics! ;)

When I first started turning bowls, I roughed everything out, double bagged each bowl making sure they were embedded in wet shavings and then waited for 9 months to a year before turning. Most often, when it came time to finish turn, the bowl blank had cracked badly and was unusable.

When the DNA method first came to my attention, I decided to give it a try. I had success with it – not 100% - but very good success and stuck with it when I moved on to hollow forms. Many will argue that DNA makes no difference in actual drying time but I can finish turn a hollow form in 4 - 6 weeks and was not able to do that when brown bagging. Just my experience – yours may be different.

There are lots of opinions on this subject – some scientific – some not. Easiest thing to do is to give it a try if you are curious and see if it works for you. If it does…. Great! If not, then move on until you find something that does work for you.

While temperature and humidity are major factors when it comes to controlled drying of your rough outs – the one thing that I believe has more of an effect than anything else – no matter which drying method you use – is that of consistent thickness! When I was first having all my troubles with rough outs cracking – I had very little turning experience. The rough outs all had varying thicknesses and I have since learned that it was that variance that created the cracks – not how I dried the wood!

A lot of folks (very experienced turners) air-dry their RO’s and have very good luck with it. More than anything else, I surmise it is the result of consistent wall thickness and a moderate climate within the drying location that accounts for their success.

So, experiment with different drying methods to find something that works for you, but at the same time, pay more attention to the actual turning to insure best results.

Good luck!

[Curt Fuller]

Some of you guys are just to smart for your own good ;). DNA is magic, pure and simple!

[Jim Heikes]

This description doesn't follow for me. During normal processing, wood takes years to dry... but an alcohol-soaked chunk will be at room humidity levels within a few weeks. Air-dried and alco-dried pieces from the same tree also appear to deform by similar amounts. Lignin softening may be a side benefit, but it doesn't appear to be a major effect. I'll have to think on it some more, but I question the validity of cell wall softening happening at all via alcohol... heating the water contained within the cell wall, yes, but not alcohol.

Don't shoot the messenger. I'm only relaying what is reported in the literature by several different sources.. Sorry for adding additional information that is pertinent to the discussion. I didn't realize differing opinions weren't well received

[Larry Marley]

This is always fascinating to listen to. I have one alternate method...
Dimension all the wood and kiln dry it. Then cut complementing species of this wood into hundreds of little pieces and then glue them all together to look like a bowl blank and finish turn.
no checking, no warping, and I have a bowl blank ready to turn in only 20 to 40 hours...

;)

[Reed Gray]

I tried the DNA soak method when I first heard about it. I turn thin (1/4 to 1/2 inch thick) green wood, and let them dry and warp before sanding. The DNA soak made no observable or measurable difference in how fast they dried, warping or cracking. I did find the wrapping the outside of the bowl with newspaper and leaving the inside open to be an interesting concept. In theory, the inside will dry quicker than the outside, which will pull the outside inwards, causing it do dry in a compression mode. This seemed to do more for crack prevention than any other drying method I had tried, especially with Pacific Madrone which is my most favorite wood to turn because it warps so insanely. I have modified that drying method to wrapping the rim with stretch plastic film, like what they use to keep boxes on pallets. 5 inch roll for most bowls, round over bowl rims, stretch the film around a couple of times, about an inch on the inside of the bowl, and the rest on the outside. Does wonders! I have never tried the twice turned bowls. One side note, the DNA soak did make bowls harder to sand out than air dried, or my favorite LDD (liquid dishwashing detergent) soaked bowls.

robo hippy

[Dan Hintz]

Don't shoot the messenger. I'm only relaying what is reported in the literature by several different sources.. Sorry for adding additional information that is pertinent to the discussion. I didn't realize differing opinions weren't well received
Jim,

I wasn't shooting the messenger, I was simply stating my opinion as to why I didn't agree with your quoted material... it wasn't a knock on you, nor do I see anything in my reply on second glance that should be taken that way.

[Ken Hill]

Just a thought.....wouldnt the soak in DNA help to equalize the moisture in the wood, then the alky evaporates leaving a more balanced (moisture content) RO?

Ive done everything here, anchorseal, dna soak, wrapped in paper, wood chips etc and none have been 100% perfect but I get far less movement and cracks with the DNA. Frankly, I could careless about the why, I would do a voodoo dance around a RO if I thought it would help. I do believe that your areas weather or atleast the conditions in your area used for drying and the wood itself plays more into the entire picture.

[Jack Mincey]

I don't use DNA but I do have some info that might be of help to turners. Between me and my students we rough out 250 bowls a year and dry all them by just placing them in a brown bag. We have around a 5% failure rate which is good in my way of thinking. The most important thing in this success is turning rough outs that do not have any small checks in them to start. If you have a small check in the blank to start with failure is probably going to happen no matter which method of drying you use. Next most important thing is having a consistent wall thickness through out the roughed out bowl. I like for the bottom to be just a touch thinner than the rim. This helps let it move some as it dries. Next item is the shape of the bowl. straight up and down walls on a bowl make it more likely to crack so if you have rough outs that crack look at the shape and keep this in mind. One thing that I have found is that the larger the tree the blank is cut from the less likely it is to crack. I have been turning mostly blanks from trees that are 40" plus in dia. which helps a lot in the stability of the blank. Last is the species of the tree, some are stable and some are not. The redwood I turned the spring was very wet, but dried quickly and didn't move any. Most of the bowls my students have turned have been from a very large maple tree. The last failure I had was from a beach tree. I and my students turned 4 rough outs from the wood and all of them cracked badly.
Happy Turning,
Jack

[Ken Whitney]

Jack,

That is very helpful information and it points to one of the problems in evaluating any drying method. Too many variables - species, shape, size of blank, etc.

Out here on the left coast my shop (garage) temperature varies from the high 30s in the winter to the 100s in the summer. Humidity is usually very low. Wood just wants to crack!

Ken