Hey all. I’ve got a fundamental question I need answered for my kindergartener’s science project. What gives wood its specific color? In other words, why is ebony black and maple near white?
Edited 3/15/2005 7:24 pm ET by pino
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Edited 3/15/2005 7:24 pm ET by pino
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Replies
I'll give a kindergarten answer :-)
Because ebony is darker than maple.
On a more serious note, I'm going to guess (without going to the booshelf) that it is tannins. Let me pull my Bruce Hoadly collection and see what I can see.
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Don't know. But you might be interested to know that ebony, being such a hard wood, reminded the ancients of stone. The wood got its name from the Hebrew word ebhen, which means stone, as in Eben-ezer, "stone of help" (I Sam 7:12).
Thank you Wayne, I think we will use that in the presentation. We actually have a piece of ebony my son cut on the bandsaw. Beyond showing its color, he is plopping it into a tub of water to show that it sinks.
The same place people get their color, it's genetic. Think about it for a second, it's not the soil, or the climate as maple grows along side of cherry and walnut. The darker jungle woods grow in the same region as the lighter colored species.
I read something to that effect with the side note that within a species of tree, subtle color variation is often caused by the environment i.e. soil, temps, weather, etc. In fact, my son asked that exact question - why are woods different colors if they grow in the same forests?Still, I am trying to find out specifically what it is that gives a tree its color. Been searching the web together all night with no luck so far.Sure wish Jon Arno were still around.
Edited 3/15/2005 8:51 pm ET by pino
In Conservation of Furniture by Rivers and Umney, they say that color in organic materials is associated with the presence of chromophores,such as carbonyl, azo, thio, azomethine, etc. groups. These chromophores usually found attached to benzene or other aromatic ring structures. Intensity is modified by auxochromes such as amines, hydroxyl, and methoxy groups.
Another source of color is conjugation, a pattern of alternating single and double bonds such as in lycopine.
When sapwood changes to heartwood, extractives containing these coloring chemicals are deposited in the now dead cells. How and why I don't know, not knowing much about tree metabolism.
There's a lot more, but that's it in a nutshell. I'll leave it to you how to translate it to kindergartenese.
HTH
Michael R
"I'll leave it to you how to translate it to kindergartenese."And I will just as soon as I have it translated into English. <G>I knew I should have studied biochemistry a little closer.
Is it one of those things like photosynthesis that we just don't inderstand? Why do we need to know what makes what wood what color? Can't we just revel in the fact that wood has so many different qualities, and be content? Naw! Never!
Ahh, the questions of a six year old.Honestly, I thought the answer would be very straight forward. My son is demonstrating wood hardness by pounding nails into pine and Ipe, density by plopping ebony and cedar into water, and color by displaying a wide variety of woods. When he asked where wood gets it color, I assumed the answer would be easy. Guess I should have just said "from Minwax" <G>
And I will just as soon as I have it translated into English. <G>
I figured that might be a little more than you really wanted to know 8^), but the even shorter answer is the color comes from chemicals that the tree deposits in the cells as they change from heartwood to sapwood. Different trees produce different chemicals just as different people have different colored skin, hair, and eyes.
I'm not sure even John would have been much more help.
Michael R
Edited 3/15/2005 10:21 pm ET by Woodwiz
Just kidding, of course.Actually, you could not have out it better this time around. That is simple and concise enough for even a six year old (and his father) to understand. Thanks so much.
Yeah, it's easy to be complicated and verbose. Simple and concise takes work.
HI,
I did something like this with my youngest boy last year. He was doing a project on desert plants so we took a sample of Gidgee and a sample of Australian Cedar and compared several characteristics.
Colour - just looked at them
Hardness - we set up a little experiment where we used a hammer from a measured height (top of a bucket) onto a small nail punch and compared the depth of hole
SG - Put them both into water where one floats and the other sinks (I went through the whole rigmarole of mass/volume measured through displacement but that was 'fun to watch but over his head')
He took the samples, hammer, punch and bucket to scholl to replicate the experiment, and a year later he still has a firm grasp of the measureable/ repeatable model essential to the scientific method.
I know that I am crowing, but I dont often get the opportunity to have this much fun participating in the kid's education.
David
Sounds like your little experiment is dead-on the same as ours, except for the difference in woods. We even have a piece of Lacewood from your neck of the woods, or do you call it Australian Silky Oak?
Yes, although there is a lot of confusion between common names and botanical names in Australian timbers (there is a story that there were more plant species within 5 miles of Cook's landing than in the entire UK)
This link http://www.woodworkforums.ubeaut.com.au/archive/index.php/t-591.html talks about finishing the timber - tone is a bit culturally relevant and different from Knots.
Have fun
I've poked through "Understanding Wood" by R. Bruce Hoadley and can find no specific reference to wood color. Despite this, it's a great book - it seems to have everything else about wood (how it dries, breaks, how it's cut from logs, it's strength, moisture content (before drying) ...
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Thanks for your efforts. I'll add that book to my list.
Ahh Jon Arno, do we ever miss you
Alison
Another way you can explain the color of things is with light. Dark woods appear dark to us because they reflect less light back to our eyes. Put dark, medium, and light colored woods side by side, then dim the lights. The darker it gets, the more similar they will look.
It's the same with color which can be seen with a prism as components of white light. We see something as "walnut brown", because it absorbes all the colors (parts of the light) EXCEPT that shade of brown. Ebony is absorbing almost all the colors in the light. Light woods like basswood reflect more of the colors in the light cast on them.
Many species, in my experience, will show differences in color from tree to tree. It could be the same genetic difference that makes related humans slightly different colors. It could be the varying minerals in the soil the tree grew in. It might be the different geographic regions the trees are grown in (a tree farther north will get less light and might grow slower with denser rings) . It might be some or all of those things.
Color is what we see reflected from sunlight or room light bouncing off of things. Perhaps you could see how different woods appear with infra-red, ultraviolet, or other forms of light are reflected off them.
Dave B.
Yep, I tried to explain it that way to my son already. I'm doing my best to let him do all the work, so working with a variety of light sources might be out of his league at this age. Then again, he did resaw all his own wood samples.As a graphic designer, the theory of light and color is well understood, unfortunately not by a kindergartener. He still wanted to know what made the trees different colors. Kinda of like, " Dad, why is the sky blue?Ironically, my daughter's project is on the theory of color. being a third grader, it is a bit easier for her to grasp.
Edited 3/15/2005 10:44 pm ET by pino
Here's a sight to behold, and will illustrate well the "ebony and ivory" ends of the spectrum. There's a great picture of it at the back of Popular Woodworking mag this month -- Sandusky presentation plow plane that sold for $114,400 at auction. One-of-a-kind I hear. Picture courtesty of Antiques and the Arts Online. The picture in Pop WWing is much better though.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Edited 3/16/2005 2:02 pm ET by forestgirl
what an amazing piece of craftsmanship.
the presence of chromophores,such as carbonyl, azo, thio, azomethine, etc. groups. These chromophores usually found attached to benzene or other aromatic ring structures. Intensity is modified by auxochromes such as amines, hydroxyl, and methoxy groups. ?????.... DANG!
I think GOD just liked different colors.. Just me though!
Think about this..... the color comes from the trees parents. Mr. and Mrs. tree some time "it" trees are the same sex is often of the same tree. Anyway as the tree cells divide off of the cambium there is the genetic code that does what it does. Why is you brothers and sisters not the same colored eyes, skin etc. One is the recessive genes.
The environment does have some effects. Examples could be one of the sibling like the outdoors more, tanner skin. One have a more active live style, etc. Where as in trees minerals can effect somewhat color as well as growth speed, yet possible another enviromental effect ..........Hope this helps.........Dale
Pino needs to tell the kindergartners something. I think you (Dale) have hit on it.Trees get their color from their mommy and daddy trees. <grin>Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Pino:
This really is a hard enough question that to find out the exact answer for a single type of wood would be a big project. You may consider my answer to be a very long-winded version of "I don't know", but here are some parts of an answer. My experience is that kindergarteners can understand and remember an incredible amount of stuff, if they decide to, so here's something to try.
First, it sounds as if you've covered the way we see colors, which is pretty cool itself. White light is a mixture of colors of light that differ from one another in wavelength, just as different pitches of sound differ from one another. As the light hits an object, some light reflects, and some is absorbed. The color we see is what's left. But because of the way we see, a mixture of two colors of light appears to us much like the color in between, though two musical notes heard together sound nothing like the one in between. This distinction is actually telling us about our eyes, not really about the light itself. It it responsible for the distinction between subtractive primary colors (cyan, yellow, and magenta) that printers mix to make any color; and additive primary colors (red, green, and blue) that you can mix as light to make any color.
So what does the absorbing of some colors of light? As mentioned by others, molecules that absorb light are called chromophores. Some of these are soluble, like the chlorophyll that makes leaves green, or the carotene and lycopene that make carrots and tomatoes colored. By soluble, I mean that they can dissolve in some liquid (water or oil or...) But there are millions of different chromophores, and natural objects tend to have bewildering mixtures. But that's not the only problem. The advantage of a soluble colored molecule is that you can fish it out and figure out what it is. But many, if not most, of the chromophores in wood are a little part of a much bigger molecule that is part of the wood structure, so it can't be separated to study exactly what it is. I would expect that in many cases, there are people who know pretty much what types of structures are responsible for the color of certain types of wood, and this knowledge is relevant to predict what kinds of color changes you will get on exposure to air, light, ammonia, or other stuff.
But even if I did have a name of something, what would it mean? Some colors are formed by oxidation of tannic acid. Does that help? But perhaps the strangest feature of these colors is that sometimes very different colors are produced by the very same molecule (chromophore). There are flowers of all different colors with anthocyanin chromophores that are pretty much the same once they have been removed from the flower, but the way they are packaged causes the color difference. Or consider retinal, the chromophore in your eye that enables vision (it's made by chopping carotene in half, so that's why you want to eat your carrots). Retinal by itself absorbs not visible light but ultraviolet. But in your eye it's packaged inside one of three versions of a protein that makes it absorb red, green, or blue light.
So what makes a given molecule absorb a particular color? Well, it depends on the structure of the molecule. An analogy might help. If you pluck a string of a guitar, what determines the pitch of the sound? The length of the string, how tight it is, whether your finger is on it, and so on. If you play a trumpet next to the guitar or piano, the strings that match the pitch of the trumpet will "resonate": absorb some of the sound and start vibrating. When a hunk of light whomps a molecule, whether it gets absorbed depends partly on whether the molecule has electrons that resonate with the light of that wavelength (pitch). Bigger regions for the electrons to slosh about it (conjugation) lead to longer wavelength (lower pitch) absorption. Visible light is longer wavelength than the ultraviolet that almost everything absorbs, and red light is longer wavelength than blue.
Good luck!
Thanks to you all for your help and input.I spoke with a professor at Purdue University earlier today and his long and short of it is "there is no easy way to answer this question." So we are sticking with the line that just like people, trees come in all different shapes, colors and sizes. That is an answer even a kindergartener can handle.
"there is no easy way to answer this question." So we are sticking with the line that just like people, trees come in all different shapes, colors and sizes. That is an answer even a kindergartener can handle.
Even this old timer understood that!
My daughter teaches kindergarten and I asked her about this question in the form..
She hung up on me?
pino,
"spoke with a professor at Purdue University earlier today and his long and short of it is "there is no easy way to answer this question." So we are sticking with the line that just like people, trees come in all different shapes, colors and sizes. That is an answer even a kindergartener can handle."
Do you think you could get away with reversing that...would it make sense?
ie. unlike people, trees have different colors on the inside and look pretty similar in color on the on the outside.
I mean we are talking NW Indiana..what maybe three species...lol
What gives wood its color?
The same things that color much of what we see--the various proteins and other macromolecules that are the basic building blocks of cells and cell parts (cells being the building blocks for an organism, organisms being the building blocks of political parties (grin).
Wood is essentially the dehydrated cell walls of the tree. Plant cells are composed of cross-linked polymers of carbohydrates (sugars) combined with proteins. Lignin (a polymer that is not a carbohydrate) also makes up a fair bit of wood.
Various proteins can have different colors, especially if metal atoms are complexed with the protein. Hemoglobin (the main oxygen carrier in blood cells) is red because of iron atoms in the hemoglobin. Most plant leaves are green because of the Magnesium present in chlorophyll, although magnesium can also cause proteins to be black, blue and even red.
Not all molecules are colored because of metal atoms, but metal complexes do make up the most intense colors. Basic carbohydrates (like sucrose) and many proteins (like albumin, the main component of egg whites) are colorless. In addition, plants take up minerals through their roots; sometimes these minerals will be deposited in the wood, forming color streaks. Hence some color in the wood is linked to the soil that the tree is growing in, but most of it is due to the distinct different combinations of molecules that make up the plant, and which are regulated mostly by genetics. (For those who care, plants exhibit higher levels of epigenetic regulation than animals).
So, if you're wondering why maple wood is light colored, ebony is black, cherry is red and poplar has greenish streaks, it's basically the same reason why people and other animals come in different shades of skin, hair, eyes (though the blood is always red).
[Knew that Ph.D. in Biochemistry and B.S. degrees in chemistry & plant biology would come in handy some day.]
That sounds like a fun Science project. As someone said earlier, wood is like people, it comes in all sorts of colors. It can't be the minerals in the soil, because if that were so, how do you explain zebrawood??? Remember, different trees have different shaped leaves and different textures of bark. So... it's basically the genetics of the tree that give it its particular color and hardness.
SawdustSteve
Steve,
If you could grow zebrawood in the US I would expect to have zebrawood patterns in the tree. The mineral contents or the site where the tree is growing can affect different hues and such in the tree's wood.
Hope this helps,
Dale
I had similar conversation with Jon Arno less than a year ago. He said that the pigments were extractives pulled into the heartwood to keep it from decaying, since it was not alive. The older the tree the more concentrated the pigmentation, so an older Cherry tree would be darker red than a young one. Although we didn't actually discuss why different trees produced different pigments, what I got from him was that the coloring was essentially a result of the tree's immune system. Bill
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