DNA longevity

[Mark Pruitt]

I am VERY hesitant to start another DNA thread because I am TIRED of listening to arguments about whether or not it actually works, so those who think it doesn't work need not read further. Not being ugly, just saying if you're going to argue about it don't do it here.

The DNA "serving" I'm currently using is about five months old and has been used for a dozen or so bowls. It's getting a dark tint to it and I am unclear as to its longevity. Do I need to begin soaking longer for the same result, and how often do I need to chunk it and get a fresh "serving"?

[Brian McInturff]

Mark,
Once it get's dark, not just opaque but dark I would start a new batch. Not because it is week but I wouldn't want to darken any "light" woods. I would keep the dark though for use on dark woods. To boost the strength just add more DNA. As it weakens the level in the bucket should also go down. Right now I don't soak anything that want fit into the large cat litter bucket, which is just a little bigger in diameter than a 5 gallon bucket. Not sure if the dark would stain but my gut tells me it will at least for an 1/8" or so into the piece.
Brian

[Rex Guinn]

Mark;
I used it with Walnut and it is very dark after two bowls, but so far has not had any bad results with my lighter colored wood. It's about a month old now.

[Joe Melton]

Remnants of my Chemistry training, if still available at all, are in some of the most seldom visited areas of my cranium, but I will go to the mental cellar and see if I can find a couple of things.
First of all, alcohol and water will mix in all proportions. That is, it is not possible to put so much alcohol into water that the water becomes saturated and refuses to take any more. When you soak a bowl in alcohol, the water that was in the bowl joins the alcohol, and the resultant mixture now is "weaker" in that it now has a lower proportion of alcohol in it than it did before the soak. The more bowls you soak, the weaker the mixture is going to be. Of course, wetter wood will weaken the mixture more, so there is not really a given number of bowls that can be soaked before throwing out the mixture.
The weaker the mixture, the longer you need to soak a bowl. The mixture will never get to the point that it is all water and no alcohol, so I would say you will always get some benefit from a soak, but that benefit will diminish as the mixture gets weaker. I think at some point the alcohol will have lost so much of its potency that the soak, no matter how long it is done, just won't get enough water out to prevent some cracking. Perhaps someone could do a study of this for us!
Another factor contributes to weakening of the mixture. This is that alcohol is more volatile than water. This means it evaporates quicker. So, when you take the lid off the container, or you don't seal it well, more alcohol than water will evaporate (that smell is alcohol that has left the bucket and entered the air), and the mixture will be weaker. So, keep it tightly covered.
If you want to separate the alcohol and water, you can heat the mixture to a temperature between 96 degrees F (boiling point of alcohol) and 100 degrees F (boiling point of water), and collect the alcohol, leaving the unboiling water behind. This is the basics of a still, as some of our southern members surely know, but are probably not going to publicly avow. I don't know if this "fractionating" will leave the coloring contaminates behind in the water or if they will go with the alcohol that boils off, but it probably doesn't matter since no one of us is going to go to the trouble of separating off the alcohol.
This information is probably of no use at all.
Joe

[Dick Strauss]

Mark,
I've had the same question for a while now. I just keep mine in an air-tight container and constantly add more fresh DNA as needed. I usually leave mine soak for a few days but not on purpose (usually I forget about my pieces for a while once I've roughed them out).

Once the DNA turns dark it will slightly stain light woods but the staining is only skin deep. As soon as you turn/sand off the first 1/32", the stain is gone. As Rex said, darkness of the DNA is not an indication of alcohol concentration left.

If one of these companies were really smart, they'd make a simple and affordable test kit for people that use DNA.

[Keith Burns]

In one of the previous threads someone mentioned that there is an inxepensive way to test the mixture, I just don't remember which thread nor who it was.

The dark colored mixture has never stained any of the light woods, ie maple, etc. that I have done.

[Reed Gray]

I have found that my old LDD solution which looks like old crank case oil will darken lighter woods (like ash, apple etc.) For a while, it will sand off fairly well. But after a while, it will muddle the colors, and won't sand off. I tried to strain it, but the colore appear to be in solution, not suspended. I have a few ant hills in my yard that will get a bath soon.
robo hippy

[Brian McInturff]

It probably depends on what woods you soak as to if it will actually produce any staining. Oak will due to the tannin. As I would think any walnut that still has some of the bark left on for NE's. Also it will depend on when the wood was cut i.e. high sap content low sap content. All these factors are why I use 2 buckets. Not that I have any scientific proof but I do know from my refinishing days that tannins stain and the bark, husk, and leaves from walnut trees could be soaked and the stained water/liquid could be used for staining other woods. Soaked walnut husk produce the richest walnut stain you ever seen.
Brian

[Dennis Peacock]

Mark,

I too hesitate to even make a statement here in yet another DNA thread. But here goes anyway.

Here's my "unscientific, backwoods, what-works-for-me" solution. Now, we can analyze all this stuff 1,000,000 times, spend 700 hours just researching the things, and sit around wondering if we should or should not.....but I like to woodwork in this fashion......find what works well for me and it doesn't have to work well for the other 45 buhzillion woodworkers out there.

DNA - How long has mine lasted. I've used 3 batches of DNA in the past 2-1/2 years and through experimentation and experience only, here's how I determine when I need to make another "batch":

I don't go by "color" of the alchy as it doesn't matter what color it is as the color only goes on the 1st 1/16 of an inch. If you soak dark wood? The liquid will be "dark". Other than that, it will darken with use any way.
When to change it? Well....here's where I get off in the deep end.
I've found out through accident, that when you spill come DNA on the floor out of your "batch" and if it sits there for a long time without evaporating (like 30 to 45 minutes), then I switch to the dip method. I then dip my hand in the alchy bath and lift it to my nose. If it doesn't smeel much like alcohol any longer? I change the bath...which also proves why it didn't evaporate very quickly when it was splashed on the concrete floor.

How many bowl do I get in a batch of DNA? I don't know. I lost count after about 43 bowl blanks.

[Keith Burns]

Mark,

How many bowl do I get in a batch of DNA? I don't know. I lost count after about 43 bowl blanks.

Dennis I hate to say any more as well but I can't resist. Say you paid $40.00 for 5 gallons of DNA and you ran well over 40 blanks thru the bath, doesn't that mean that you spent under a $1.00 to improve and speed the drying process ? Man thats just way too much money for me, after all our lathes can cost $3,000.00 and more.

[Mark Pruitt]

OK, this all makes sense to me. (Does that make me dangerous?)

Dennis, I like your "spill test." I gotta remember that for the future.

Some of what has been said validates my intuition that the more I use a batch of DNA, the longer I need to soak bowls to get the full benefit. I also see that at this point I am nowhere near having to replace what I currently have. It kinda runs contrary to my thinking, though, to simply add new DNA to a weakening mixture. I see the reasoning in that, but I'm more comfortable just throwing out an old batch and starting over.

Thanks again guys. Gotta love SMC!

[George Tokarev]

The weaker the mixture, the longer you need to soak a bowl. The mixture will never get to the point that it is all water and no alcohol, so I would say you will always get some benefit from a soak, but that benefit will diminish as the mixture gets weaker. I think at some point the alcohol will have lost so much of its potency that the soak, no matter how long it is done, just won't get enough water out to prevent some cracking. Perhaps someone could do a study of this for us!
Another factor contributes to weakening of the mixture. This is that alcohol is more volatile than water. This means it evaporates quicker. So, when you take the lid off the container, or you don't seal it well, more alcohol than water will evaporate (that smell is alcohol that has left the bucket and entered the air), and the mixture will be weaker. So, keep it tightly covered.
If you want to separate the alcohol and water, you can heat the mixture to a temperature between 96 degrees F (boiling point of alcohol) and 100 degrees F (boiling point of water), and collect the alcohol, leaving the unboiling water behind. This is the basics of a still, as some of our southern members surely know, but are probably not going to publicly avow. I don't know if this "fractionating" will leave the coloring contaminates behind in the water or if they will go with the alcohol that boils off, but it probably doesn't matter since no one of us is going to go to the trouble of separating off the alcohol.
This information is probably of no use at all.
Joe

Careful, you're bringing reality into the equation! It's a mixture, really. Say the alcohol is white sand, the water black. Mixes at all proportions. You dehydrate in Histology by discarding the mix, adding more alcohol, discarding, etc. Eventually you can get almost pure white sand or alcohol. Or in the case here, black sand, since the white blows away quickly.

You can get 95.6% alcohol (4.4 water) by distillation. This azeotrope boils at 78.2C, so don't exceed that or you get more water in proportion.

To answer the question on determining the mixture, it's probably close enough to get the SG by dividing the weight by volume. The dissolved material that gives the solution color will be an insignificant amount. Ethanol is .79, water 1 gram per cc at 20C. Easy math.

It'll work the same at any dilution, really. Within a day or so. Even soaking in water for a day won't set it back as much as the time of soak.

[Harvey M. Taylor]

Since this is an unscientific forum, I will give my unscientific observations. Ahem, seems to me an anti-freeze tester should give you a rough estimate of how much alky is in the formula. After all, anti-freeze base is a lot alcohol, isnt it? At least close enough to get an 'unscientific ' guestimate, I would think.

It is either raining, or it is not raining, since it is not raining, then it must be raining.Conversely, it is either not raining or it is raining.Since it is not raining, then it must be raining.
I think that just gave me a headache. Max

[Mark Pruitt]

It is either raining, or it is not raining, since it is not raining, then it must be raining.Conversely, it is either not raining or it is raining.Since it is not raining, then it must be raining.
I think that just gave me a headache. Max

Harvey,
Come in out of the rain!!!

[TYLER WOOD]

I'd be careful about spilling DNA on the floor.

That's why some people get caught!!! Plus blood stains wood!!! Found that out the painful way.

Oh sorry I didn't realize we were talking alkyhol!!!