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George Tokarev
11-23-2004, 4:33 PM
Science always doubts, only faith has the answers. Those who have faith should not read this posting. For those who have doubt, perhaps this will clear up some of it for you.

As I said in response to a challenge issued by Dave Smith, for which I have been roundly criticized, there is ample empirical data of the process by which wood loses unbound and bound water to the environment, and methods other than letting it be merely accelerate the process by exploiting extremes. Heat/dehumidification/vacuum methods all take advantage of the lower relative humidity produced to get the water out. There are no known chemical methods, save dehumidification by dessicants which do not alter wood chemistry.

So, what is it that alcohol, specifically ethanol, does to wood to make it lose water faster? Wood naturally contains alcohols, so chemical modification is certainly unlikely. Alcohol influence-bonds with the wood structure poorly compared to the more electronegative water, so significant displacement of bound water also seems unlikely. Still, we are informed that this is a proven process, so this possibility must be investigated.

Without boring you too much by by specific data on weights and times, the method by which I attempted to discover if alcohol soaking displaced or replaced (unbound or bound) water follows.

Blocks of soft maple 2x2x1", with the 1" along the grain, were prepared randomly from the center 12" of a single 2' length and compared. They were all within four grams in 60, which is pretty good considering I whipped them out on the bandsaw pretty much by eye, and the dull blade wandered. To determine if alcohol could enter and replace either unbound or, much less likely, bound water, I tagged a quart of denatured alcohol with brown alcohol-soluble dye to get visual confirmation of penetration which I might correlate with a loss of weight caused by the lower specific gravity alcohol (0.80) displacing water. The soaking took place at 68 F, in a closed container.

A control block was tightly wrapped after weighing, a second control was microwaved to determine that moisture content was above the fiber saturation point. It was, at 42%, 12% by weight over the normal FSP.
The first soaked block was removed after nine hours, blotted to remove surface alcohol, and weighed. It was identical to the original weight, nicely brown, and was microwaved to reveal a 41% MC, then sliced to reveal insufficient penetration by the dye along the end grain to make a reliable estimate of distance.

Conclusion: A nine-hour soak did not lower the MC of a block of soft maple, nor was any loss in weight from replacement of water with lighter alcohol evidenced. Penetration of the dye was minimal to nonexistent by eye, in confirmation of the above.

The second block was removed after soaking for 24 hours, weighed within 1/2 gram shy of the original. The second control was unwrapped, weighed at 1 gram less, which I attribute to moisture on the wrap. The two were then set side by side on a piece of notebook paper for 60 hours in a nearly steady 65% RH environment. The soaked block lost weight at the same rate as the control, reaching 20% after a bit more than 48 hours. They were allowed additional time, but as they were almost the same, there seemed no purpose in continuing. Unbound water was lost at the same rate over the first 24 hours, and bound water seemed to be following the same course.

Conclusion: A 24 hour soak may have resulted in the replacement of up to two and one half grams of water of an anticipated total of 32 by ethanol, though it did not affect the dry time to the FSP or beyond, at all. It is possible that the use of this analog scale versus the digital I borrowed before might account for the difference. In any case it does not appear to have affected the outcome. The penetration of alcohol on the end grain is pictured. There is visible, consistent penetration of ~1/32 of an inch.

I'm saving the rest of my alcohol for mixing shellac.

Oh yes, Kurt, the scientific community among the ancients knew the earth was spherical by observing its shadow on the moon. The Greeks even measured its circumference accurately. The belief that it was flat was based on religious authority in defiance of scientific evidence.

Kevin Gerstenecker
11-23-2004, 5:09 PM
If you wanted to compare apples to apples, why didn't you follow the process to the letter and use rouged bowls with a wall thickness of 1/2" or, for a larger bowl, a bit more? I am not as impressed as you obviously are with yourself George. Sheesh, get over it dude. :rolleyes:

Bart Leetch
11-23-2004, 5:52 PM
If you wanted to compare apples to apples, why didn't you follow the process to the letter and use rouged bowls with a wall thickness of 1/2" or, for a larger bowl, a bit more? I am not as impressed as you obviously are with yourself George. Sheesh, get over it dude. :rolleyes:


I agree 100%.

George Tokarev
11-23-2004, 9:00 PM
Your polite, well-measured replies noted, but, apparently you did not read the temperance maple experiment, where I did exactly that.

It appears you have little respect for scientific methods of exploration. The pity is you also appear to know little or nothing about your chosen medium upon which to base the opinions you expressed. Since anything worth doing is worth doing well, I would recommend such a study, commencing with the free material on line at http://www.fpl.fs.fed.us/tmu/publications.htm

There you will find that the tangential shrinkage percentage for red maple is 8.2 percent. What this means is that a 10" (to keep it simple) bowl can be expected to shrink .82 inches from green to oven dry. If the sides of your bowl are at all bell shaped, rather than vertical, you may regard that as a worst case scenario, since the wood will find a bit of room to deform downward rather than purely across, and is purely tangentially grained at only one point in the cross-section.

Thus, if you want to make the rim thickness of your final bowl 1/4", the dimension for absolute safety is .66 thickness on the rough. Demonstrate this to your satisfaction by drawing concentric 10", 9.18" and 8.68" circles. You bowl will fit tangent to the inside of the long-grain direction and tangent to the outside of the cross-grain direction. Since the figures given are to oven dry (0% MC), you have greater latitude than that. With me so far?

Now with only .66 thickness, and about 1000 rpm to eject unbound water, you can be extremely close to the fiber saturation point of ~30% MC when you dismount your rough. It is below this point that distortion begins, in rough percentage to the decrease in moisture content. It is also at this point that end checks can form if the moisture gradient is not controlled. Care must be exercised to assure that the outside of the piece does not dry significantly faster than the inside can pass along its bound water. This depends on the RH, MC, and species of wood. Our example of red maple has a low tendency to check. That's why it can tolerate open air and 70% RH or lower drying, as in my temperance example.

Since you're already close to the FSP, you've got a pretty good leg up on the drying time, which is listed as 30-120 days for planks, let alone end grain, which dries at ten times that rate. Let's take 60 days and 10 times as our figures, arriving at a theoretical 6 days to 25% from absolutely green. Imagine how much more quickly we can dry from an initial 30% to a good indoor 10%. I'm almost certain from years of experience, that the last few percent come at a slower rate than the initial, but you can see that without doing anything at all, we can reasonably expect a 10" (9.18") bowl to be usably dry in a week to ten days.

If we want to protect our piece against any degrade whatsoever, or if we want assured success with those species prone to checking, we can slow the initial loss by maintaining a higher initial RH. One of the best ways is to bag it in paper. This works well, because the paper will take moisture up to the same FSP as wood before evaporating much into the environment, creating a great bowl in a bowl effect. As noted, though the anchorseal people will probably disagree, checks don't form on the inside curve, so all we really need to cover is the outside.

Does this sound like "the protocol" less the alcohol? It ought to.

It works because we've planned a minimum thickness rough to accommodate maximum drying rate and known maximum distortion. We need only modify it, using good common sense, for extremely low RH, irregularities in the grain of the piece which we know will distort out of the ordinary direction, and the species under use.

Therewith George's quick dry method. Alcohol doesn't soak in worth squat, as demonstrated, doesn't change the chemical or physical characteristics of the material where it does, and costs money. We can substitute science and good sense in its place.

Hank Walczak
11-23-2004, 9:39 PM
Well done George - But you must remember there still is a Flat Earth Society. So no matter what, people will believe what they want to believe. And you can take that to the bank.

Hank

Rob Bourgeois
11-23-2004, 10:07 PM
George
I see a few possible errors in your methods based on my knowledge as a toxicologist/physiologist. ( Shrimp not plants but principles are the same)

The first thing is the dye although it is a small molecule is much much bigger than the alcohol so penetration will not be the same. It will also not be absorbed internally (cells) as readily as alcohol. If you want to really measure the penetration, you need to use radioactively labeled alcohol ( and even then its a heavier molecule). This is something that I dont think you could afford to do or have the equipment.

The second thing is you state " nor was any loss in weight from replacement of water with lighter alcohol evidenced." Alcohol again is heavier than water, roughly 3 times at a molecular level which is what we are dealing with intracelluar water. The alcohol molecules are bigger thatn the water molecule and by simple diffusion the water will move from its area of high concentraion to areas of low concentration...(ie out of the cells).

In conclusion, something I haven't posted here or else where about the alcohol procedure is that this is a very similar procedure used to dehydrate tissues for use in preparing slides for microscope work. I have seen animal, algae and plant tissues dehydrated using an alcohol gradient system. So this procedure does have some scientific merit to it besides the evidence that others have shown with there bowls turned with this method.

In conclusion, other than what people have said and my knowledge of a similar system to dehydrate tissues, I will still test this method using the procedure as described using a good solid scientific study. Mainly because I am a scientist and thats what we do - experiment. Dont expect any results soon since the lathe is not working yet.

Rob

Bart Leetch
11-24-2004, 1:40 AM
I'll admit I can be wrong about anytime & even almost all the time. But...I am not educated in some of the thing you list of so easily. However I do know that you can prove this out a lot easier & closer to what Dave did for all to see by doing the actual work of turning a bowel & going through all the steps posted by Dave. Of course that would take a little more time & effort & may show exactly the same thing you've already shown...& then again it may not.

But then again it may not according to the post by Rob.

Remember there is always that ...maybe...what if...gee I wonder....that is how all the things you did your best to explain came to be known.

There may still be an unknown here to be learned.

There is an old saying that I like to remember because it fits me & everyone else on this earth.

Remember the book of what you don't know will always be bigger than the book of what you do know.

Doug Jones
11-24-2004, 4:10 AM
My hat is off to Dave, for taking the plunge and going the extra for an improved and faster way of dryingbowl blanks.Of which I am doing now.

George and others, if we stopped trying to improve various methods and things,,, your last post would have been written with a feather dipped in a ink well tied to a pigeon's leg and still be in transit. I'm not an educated guy, but I'm also not so ignorant that I will right off a procedure without giving it a fair shake.

Sparky Paessler
11-24-2004, 7:57 AM
I think that George and Dave have both made good points. I am just getting into drying bowls and plan to try several different methods. I appericate Dave giving me another option to try. I also will keep in mind George's point that the bowl might dry just as fast on its on. I think that the best thing to do is when you are trying these methods (boiling, alcohol, freezing, etc.) to compare them to drying a similar bowl without doing anything to it. Then use what works best for you in your situation. I don't think that we will all agree on what is the best method but it does make for some lively discussion. :D

Sparky

David LaRue
11-24-2004, 8:09 AM
I read elsewhere that some turners (I'm a newbie to turning) boil their bowl blanks in water. How does this method compare to other methods that can be used to accelerate wood drying?:confused:

Bill Grumbine
11-24-2004, 9:14 AM
Good morning all

I was one of Dave's testers in the experimental group. I know very well that my own personal contribution standing on its own does not constitute a scientifically accurate sampling. I do not have enough data to do an analysis of variance to see if my results are statistically significant. Do you know what?

I don't care.

I am not really interested in devoting the time and energy necessary to discover the mechanism, if there is indeed a mechanism, by which this process works. People have been looking for ways to dry wood faster since there have been people drying wood. Anyone who knows me even a little bit knows that I am not a relativistic sort of person. However, in this case, I can say that if it works for you fine. If you don't think it works, and you don't like the idea, fine. Go do something else. I have tried this method on several species in a number of different situations. It is not 100% effective, but it is as effective as drying bowls in any other manner I have tried. The big difference is that it has dried them faster. Of course, I am a person of faith first and science must align with my world view. Call me what you want, but I know a thing or two about wooden bowls, and I know this works.

These forums are here for fellowship, communication, and for helping one another out along the way. There does not need to be acrimonious behavior to get one's point across, and no one is betting their life on anything here. If they are, then there needs to be some serious reexamination of their priorities and perspectives. Dave has put a lot of time and effort into a process he has freely given away. He is not traveling the countryside selling this stuff as Dave Smith's Patented Bowl Curing Formula, he GAVE IT AWAY to whoever wants to use it. George, for whatever reasons, you do not seem to like his method or conclusions. I have not read all the posts, and frankly I do not intend to do so. You have made your point very clear that you disagree on a number of points. Fine. No one is going to come to your shop and make you soak your bowls in alcohol.

A few years ago, another accomplished turner who was also a personal friend of mine asked me to be one of the secret participants in a different method for drying bowls quickly. His name was Phil Wall and the method was soap soaking. Yes, I was involved in that one from the very beginning too. Phil worked closely with another man to write up an article with results in the Journal of the AAW. Since then the method has been endorsed by a number of people, Ernie Conover being one of them. Although I tried it out, and was in on it from the beginning, I did not find that it was profitable for me, and I discontinued its use. But you know what? If other people are getting good results with it, that is GREAT! Far be it from me to start an argument with any of them. They have their way and I have mine. That is all the farther it needs to go, and in this case, I think the same thing can be said.

Bill

Kent Cori
11-24-2004, 9:40 AM
Well, this is certainly an interesting debate. :rolleyes: I am an engineer and we specialize in the practical application of various processes. Many of these are empirical in nature meaning they are based on real-world results that are often not easily supportable by scientific experimentation. We often simply don’t understand the complex and interdependent relationships and external factors that may occur with a given process.

Fortunately, most engineers are happy to apply a process if it works and is consistently repeatable. We try to leave it to others to figure out how and why it works while we put it to use for the good of the general public. This seems to be one of those cases. From what I have read, the process works. Maybe someone can figure out why but in the meantime I intend to use it at my next opportunity.

Bob Hovde
11-24-2004, 9:46 AM
Could it be that George and Rob are rushing down parallel lanes on the same road? Assume alcohol DOES replace the water in the wood. If the total process of exchanging water for alcohol and then drying the wood takes as long as just drying the wood slowly by itself, has anything been gained? It might, if the subsequent rapid evaporation of the alcohol causes less stress on the cells than the original evaporation of water would have. Otherwise, there probably isn't any advantage. At this point, we don't know if the alcohol replaces water in wood - and we don't know that it doesn't. Further, I don't think we know if it even makes a difference.

I'm more worried about checking than warping. All I know is that when I soak a cherry (rough) bowl in LDD before finishing it, it is less likely to crack. I haven't tried to soak them in just water, but that might do the same thing. It certainly keeps the bowl wet until I can get it turned thin. Maybe it's because I've only turned thin bowls, so the stress gradients might be smaller. They warp, but don't crack (usually).

How am I supposed to remember chemistry from 40 years ago? :confused:

Bob

Ted Shrader
11-24-2004, 10:09 AM
Bill -

Thank you for that post. You have an enormous amount of credibility and vast experience in the practical aspects of wood turning and drying. Your input on this, I'm sure, mirrored the thoughts of many.

Regards,
Ted

Jim Stastny
11-24-2004, 12:19 PM
Oh yes, Kurt, the scientific community among the ancients knew the earth was spherical by observing its shadow on the moon. The Greeks even measured its circumference accurately. The belief that it was flat was based on religious authority in defiance of scientific evidence.


Great work, I appreciate the effort. However, for the sake of precision the notion that the flat earth theory was upheld by religious authorities in spite of scientific evidence is often misused. The religious authority at the time of Copenicus opposed him BECAUSE of the scientific community in place at that time. For fourteen centuries before Copernicus western astronomers based their science on the book, THE ALMAGEST, written by Ptolemy. Using Ptolemy's 'science' the astromomers came to such conclusions as the earth being flat. The religious power of the day, under the influence of the astromers, then suppressed Copernicus' theories. I mention this because many will use this to foster the errant idea that religion and science are antithetical to one another. Such is not really the case.

Barbara Gill
11-24-2004, 6:39 PM
Thanks Bill. Well said!

Jim Ketron
11-24-2004, 8:43 PM
I will 2nd that Barbara

Jim

Christopher Pine
11-24-2004, 9:16 PM
Thankyou for your educated commenst Jim!