DNA Question

[Dick Wilson]

There has been a lot written about using DNA to dry wood. I am not sold on David's chicken smultz theory yet. But I am curious:

Without spend gobs of time away from the lathe to research this can someone explain to me in simple language, in less than 200 words, what exactly happens when DNA hits water molecules? What does the water turn into, if anything? After the reaction takes place is the wood now "dry" enough to turn to finish without warping and checking??

What if: You turned a bowl green to finished thickness, say uniform 1/4" wall thickness and then flooded the piece (inside and outside) with DNA. With that wall thickness I would have to believe that the DNA would completely soak through the wood. After the DNA evaporated would the bowl now be "dry"? And you could turn the lathe on and centrifigal force would pull the DNA through the wall ???????

Just wondering. These are the momentus issues of the day that I think about as I am falling asleep:D:D:D

[Cody Colston]

I don't know what happens and don't really care. It's been my experience that soaking in DNA expedites the drying process and minimizes cracking...how it does that is a question for the chemists, of which I'm not one.

One common misconception is that soaking in DNA prevents warping...it does not. That's why vessels are rough-turned to 10% of diameter, so that the piece can be trued after drying and still retain sufficient wall thickness.

I now return you to your regularly scheduled forum surfing...

[David E Keller]

I'm not gonna count the words, but here goes... The DNA displaces the water in the wood. Nothing magical happens to the water. The DNA evaporates faster than water which leads to more rapid drying. I don't know anything about plant biology, but it has been suggested that the DNA may harden the cell walls within the wood helping to minimize warping, etc. Lots of variables impact the drying process.

Not sure about your 'flooding the wood' experiment as I think it would take longer than that for the DNA to displace much of the water within the wood. At 1/4", it's not going to take long to dry anyway.

[Reed Gray]

With thin turned green bowls, DNA soaking does absolutely nothing you can measure, or observe when compared to air dried, or LDD soaked (liquid dishwashing detergent), other than make the wood harder to sand out. I did about 500 bowls that way before I went to the LDD which makes bowls a lot easier to sand out than air dried or DNA soaked. This type of bowl is dry in 10 to 14 days max in my western Oregon shop. I do have a small heater, but away from the drying area.

robo hippy

[John Hart]

It is my understanding that the plant cell hardens because it is dead. The alcohol kills the cell. The water is displaced by the alcohol. Aside from that...I dunno.

Seems like common sense... Sure is a lot of mystery on this subject.

[Ken Whitney]

Chemistry Part

Water and DNA are miscible. They do not "react" in a chemical sense but they do mix together because they have slight positive and negative parts on the molecules (they are polar molecules). Water doesn't mix with oil (i.e. salad oil) because oil molecules do not have the slight charges (oil is non-polar).

If you put a piece of wood (lots of water, hardly any alcohol) into DNA (lots of alcohol, hardly any water) the water in the wood "sees" a lower concentration of water outside of the wood and water will move until there is an equal amount of water inside and outside of the wood. And the alcohol will "see" that there is less alcohol in the wood and the alcohol will move until there is an equal amount of alcohol inside and outside the wood. This is, more or less, simple diffusion.

Plant Part

Wood is mostly cellulose, lignan, pectins, gums, resins, etc. The plant cells in wood are mostly dead cells that simply provide for conduction of water and support the plant. There is free water in the cells that is easily extracted and there is water more closely bound to the cells that is less easily extracted. The so-called equilibrium point is when bound water can no longer leave the wood under the current conditions (i.e. humidity, temperature, etc.).

Woodturning Part (ironically the Sawmill Creek spell checker doesn't like "woodturning")

DNA evaporates faster (at a lower temperature) than water and may cause less stress on the wood when it does evaporate. So, theoretically, you get faster drying and less cracking with DNA.

Editorial Part

If your eyes haven't glazed over (assuming you've gotten this far) I know that there are all kinds of simplifying assumptions in this, but this seems to me to be a reasonable explanation of why the DNA method might work.

Note that this "dehydration" via alcohol is often used when tissue samples are prepared for microscopic examination. Such tissue samples are usually infiltrated with wax or epoxy so that they may be cut in very thin sections. Since wax and epoxy are not particularly miscible with water the water in the tissue is removed initially via an alcohol soak.



Ok, more than 200 words, but the Chemistry and Plant parts are about 200, so you can stop there if you want.

[Dan Hintz]

Ken,

I see nothing wrong with your description and is essentially my belief on the matter. I still want to hash it out with one of our microbiologists, but I'm pretty certain whomever I talk to will be in agreement.

[Ken Whitney]

Dan,

I'll be interested in hearing what you find out.

I do have an alternative explanation (that doesn't involve schmaltz!) but I'm reluctant to share at this point:)

Ken

[Tony De Masi]

I'm with Cody on this one. Does it work? Yup. How? Don't know and honestly don't care. I've lost one bowl in five years. It was apple, and I just didn't soak it long enough. I'm sold.