- Thread Starter Thread Starter
- #61
Agreed.
There should be two different words:
One for "figure" related to colour (like Olive, Ziricote, etc) and one for "figure" related to chatoyance (like quilted Maple, mottled Makore, etc)!
Most chatoyant wood species?
- Thread starter chatometry
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There should be two different words:
One for "figure" related to colour (like Olive, Ziricote, etc) and one for "figure" related to chatoyance (like quilted Maple, mottled Makore, etc)!
First off, it should probably be said that what we call "figure" is not always wood-grain (growth rings). Would it suffice to say that all wood-grain is figure? Chatoyance is not wood-grain, but can be figure.
I go back to an earlier question - can it be determined (or has it been determined) what is the "cause" of chatoyance? Is it cell walls? Pores? Chemical composition? Minerals present? Amount of moisture in the wood? Little green men with ray guns trying to shoot out the lights?
Ok, I now understand that your light is traversing a circle around the lens axis. That changes things. Out of curiosity - at what distance above the plane of the wood does the light travel and at what distance is your equipment from the wood? So, assuming the light travels on a plane parallel to the plane of the wood, then the angle of incidence is the same for 360 deg of travel. Lets call that the apparent angle of incidence. Yet the angle of reflectance appears to change. This same phenomenon happens when the light travels in an arc above the wood from side to side 180 deg. In that instance, the angle of incidence is changing. In the same piece of wood are your measurements different between the two light travels?
Allow me to postulate that the changes in the light measured are due to the same effect - the change in the angle of reflectance. If that is not correct, please correct me. In the light moving in the arc - all factors are constant but the light and the angle of incidence. In your circular motion, everything appears to be constant (except of course the light - but the apparent angle of incidence to the plane of the wood is constant). Yet the reflectance changes lead me to deduce that something in or on the wood is not constant that is such that changes the ACTUAL angle of incidence and therefore the angle of reflectance.
With my limited knowledge of wood - I assume that unfinished wood is opaque and light does not travel THROUGH the surface and hits something and reflects back out (as a mirror), but acts more like a polished piece of metal. So to me, there is something about the surface of the wood that causes chatoyance. But the surfaces of the different woods you used are superficially prepared the same - so that leaves something in the wood itself.
I know very little about the structure of wood, but would assume those woods that reflect more light - have more pronounced chatoyance - do they have more unity? Do they either have more of what reflects the light or what reflects the light is more lined up and/or denser- so to speak. Those woods/pieces of wood with less apparent chatoyance either don't have as much of what reflects or what they do have is not lined up or as dense or somehow otherwise disperse (less focus) the reflected light.
Does the chatoyance increase of decrease with the type of cut - i.e. rift, quarter, plain, live? Does it change due to where from the tree the wood comes from - near core - near bark? Is it same with a transparent finish? It seems to be more apparent often in places of stress in the tree - crotches, downhill sides, in buttresses, etc.... Or do those stresses bend that which causes the chatoyance into different configurations that change the angle of reflectance?
I go back to an earlier question - can it be determined (or has it been determined) what is the "cause" of chatoyance? Is it cell walls? Pores? Chemical composition? Minerals present? Amount of moisture in the wood? Little green men with ray guns trying to shoot out the lights?
Ok, I now understand that your light is traversing a circle around the lens axis. That changes things. Out of curiosity - at what distance above the plane of the wood does the light travel and at what distance is your equipment from the wood? So, assuming the light travels on a plane parallel to the plane of the wood, then the angle of incidence is the same for 360 deg of travel. Lets call that the apparent angle of incidence. Yet the angle of reflectance appears to change. This same phenomenon happens when the light travels in an arc above the wood from side to side 180 deg. In that instance, the angle of incidence is changing. In the same piece of wood are your measurements different between the two light travels?
Allow me to postulate that the changes in the light measured are due to the same effect - the change in the angle of reflectance. If that is not correct, please correct me. In the light moving in the arc - all factors are constant but the light and the angle of incidence. In your circular motion, everything appears to be constant (except of course the light - but the apparent angle of incidence to the plane of the wood is constant). Yet the reflectance changes lead me to deduce that something in or on the wood is not constant that is such that changes the ACTUAL angle of incidence and therefore the angle of reflectance.
With my limited knowledge of wood - I assume that unfinished wood is opaque and light does not travel THROUGH the surface and hits something and reflects back out (as a mirror), but acts more like a polished piece of metal. So to me, there is something about the surface of the wood that causes chatoyance. But the surfaces of the different woods you used are superficially prepared the same - so that leaves something in the wood itself.
I know very little about the structure of wood, but would assume those woods that reflect more light - have more pronounced chatoyance - do they have more unity? Do they either have more of what reflects the light or what reflects the light is more lined up and/or denser- so to speak. Those woods/pieces of wood with less apparent chatoyance either don't have as much of what reflects or what they do have is not lined up or as dense or somehow otherwise disperse (less focus) the reflected light.
Does the chatoyance increase of decrease with the type of cut - i.e. rift, quarter, plain, live? Does it change due to where from the tree the wood comes from - near core - near bark? Is it same with a transparent finish? It seems to be more apparent often in places of stress in the tree - crotches, downhill sides, in buttresses, etc.... Or do those stresses bend that which causes the chatoyance into different configurations that change the angle of reflectance?
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Boy I wish I could retain half of this thread!
No, it cannot. "Figure" is specifically things like ribbon stripe, curly, etc. Chatoyance can ENHANCE figure but it is not figure.
Also, I take it you do not agree w/ my post #50.
I have purposefully not gone to look for some standardized definition of "figure". I am currently sitting in front of a sample of rather fabulous curly koa. If I look for wood grain - it is almost non-existant. Yet it is considered "highly figured" and sells for an amount commensurate with the amount of figuring! If I look at the piece at 90 deg from the apparent surface plane - I see a lot of "figure". If I look at the piece at some angles of 45 deg and less, the figuring almost disappears. To me, what they are measuring is generally the amount of light reflecting from the surface of the wood at differing positions of the light. If in the cycle of the light if the surface of the wood is dark is NOT because there is no light reflecting off of if, but rather the light reflecting is not being reflected into our eyes, camera, meter, etc... Or, since this is not a perfect world and we don't have perfect surfaces, then I guess it would be more correct to say - if the wood is darker during the light cycle, then the prevalence of light is reflecting elsewhere and if it is lighter then the prevalence of the light is being reflected into our eyes, camera, meters, etc.... The only reason we would normally know that there is curl, or ribbon stripe is because of the differing quantities of reflected light. There may be some structure to the wood that microscopically we might be able to ascertain - but normally, at normal viewing, we would not know there was any "figure" without the differing reflections. So I'm not sure you can separate the two. Can chatoyance exist with out "figure" - it appears so. But can certain figuring exist without chatoyance - I guess they can, but you might not be able to see it.
- Thread Starter Thread Starter
- #66
I think literature says it is due to cell walls, but I am not expert on this. Surely it has to be something common to both softwoods and hardwoods.
We cannot run this kind of test. However it would be hard to find a meaning in such data, as you would have a variable light intensity, all sorts of glare issues, etc.
You are thinking of a surface made of plenty of micro-mirrors oriented at an angle which is different from that of the nominal surface plane. This may be true. However I am more inclined to thinking that fibers reveal a different colour depending on light direction. But I don't know, it would be interesting to find out.
Absolutely. There is an undeniable difference between wood species.
I don't know. At the moment the question (for those who know a lot about wood) is: what do {Iroko Khaya Sapele Okoume Makore} have in common that {Olive Ziricote Cedar(Leb) Wenge} do not have?
We did not see a significant impact of cut, with the following notes:
1) Softwoods are more chatoyant in their late growth rings (see example below). If your measurement area is on a QS surface you average correctly a number of early and late growth rings. But on FS surfaces you may end up with a measurement area that is mostly on late growth ring, thus reading a higher value, and vice versa.
2) Some cells (I ask wood anatomy experts to correct me if I am wrong) like medullary rays or flecks may have a different chatoyance; so this might make cut type relevant.
3) Figure may highlight chatoyance, and figure depends on cut.
No idea. We did some qualitative tests here:
We will do more.
This is a good point: some finishes (shellac, BLO, ...?) are known to enhance it while some (in my experience flooring transparent finish) dampen it. No idea why...
The microscopic structure of latewood is different than that of earlywood in softwoods. The earlywood is generally much softer than the latewood. The extra density of the latewood is what makes its structure more chatoyant. Similarly, the microscopic structure of rays is different that that of non-ray areas. ALL of chatoyancy is due to differences in the microscopic structure of the different areas of wood and the fact that they cause light to be reflected differently at different angles because they themselves have different angles relative to the nominal surface of the wood at the macro level. I just don't get why everyone is having trouble with this concept. It seems very straightforward to me.
- Thread Starter Thread Starter
- #68
Two players are missing: the direction of the light and the direction of the fibers. Make a sinple test, using your smartphone torchlight: look perpendicularly at the surface and light it with ~45° incidence angle. Then rotate the light around your optical axis and see what happens. For each point of the surface you should see max brightness when the light beam (projected on the surface) is roughly perpendicular to the fiber in that point.
Maybe, or maybe because light gets absorbed into the fibers...? (I don't think so, however, because chatoyance is also very evident on split wood).
Fully agreed.
Why? We have examples of non-chatoyant very dense woods (Buxus Sempervirens, Olive, ...).
Yes, that was an incomplete statement on my part. What I meant was that the heartwood density of THAT softwood makes it different than the sapwood of the same piece because of the different micro structure of that heartwood vs sapwood. I did not mean to imply that density always means chatoyancy, as it clearly does not.
i have noticed a chatoyancy to the rather soft bland pallet wood from vietnam, that was decided in another thread was the plantation raised hybrid acacia
pallet wood nice contrast id help please
UPDATE: @vegas urban lumber --- Well, I'm no longer convinced that it's Acacia mangium, even though the end grain is an excellent match. The problem is that except for The Wood Database, which is completely at odds with other reports, Acacia mangium is a very hard, heavy wood used for heavy...
woodbarter.com
I have some (what i'm told by Mark Peet is some kind of fig) that has some incredible chatoyance. at least when a finish is applied... Desert ironwood is another. One thing I have noticed about DIW is the older wood, that has been dead a long time and darkened, loses a lot of it's chatoyance....
@chatometry, Is there a pic or illustration of your chatoyance measuring setup? Better yet a video that shows it action?
- Thread Starter Thread Starter
- #73
Thank you. Was it a rough, finished or split surface?
Interesting - is it figured? What color is it (just to have a rough idea)?
Good point. But... is it time since dearh, or is it time since sunlight and/or oxygen exposure?
All our tests are made on freshly sanded wood, but this page shows a comparison we made before and after quick (1 day) sunlight exposure on Purpleheart:
Anyway my experience tells me you are surely right on some woods, such as Padouk which eventually turns almost black. I don't know if ALL woods would eventually lose their visible chatoyance, and how long it would take.
@Karl_TN I will see what I can do.
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Good point. But... is it time since dearh, or is it time since sunlight and/or oxygen exposure?
All our tests are made on freshly sanded wood, but this page shows a comparison we made before and after quick (1 day) sunlight exposure on Purpleheart:
Sunlight exposure – PZC Chatometry
It is the age of wood overall, even if you cut to the middle of an old piece, there is less chatoyance, it is a resinous wood, which eventually oxidizes all the way through...
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Here is an example of the fig; the bottom part, this is a little darker color than the samples on Paul's site, this had some gray spalting patches in it. Im pretty sure its common fig, the kind you eat...
So, @chatometry addressed the density, so I can throw half of this post away.
@ chatomety - I know I'm asking a lot of questions, but by golly, I have them - it's what makes Lil Mikey so charming! Appreciate the time you and your colleagues put into this research and you answering questions. One of the failures of our society is that because we are so loosey-goosey, words have multiple meanings and are therefore at times rendered essentially useless. So this begs the first question for today.
First question this time - Is Reflection = Chatoyance a correct statement? If so, then why the difference in terminology? If not, then what is the difference? It seems to me what is being quantified is the delta in reflectance values off of something in or on wood. Am I in the ballpark?
Second question - Is chatoyance more pronounced in radial, tangential, or transverse planes of presentation?
Third question - since the wood we use is "dead" some for a longer time that others. And what we have left is basically dried up cell walls, have you tested any very freshly cut wood, before the cells have had a time to dry out?
Fourth question - Since when you cut and sand a piece of wood you essentially cut what used to be cells and pores. I suspect for the vast majority of a cut and sanded wood surface, if you magnified it, you would be seeing the insides of what used to be the cells. Take a look as some electron microscope images of wood. Sanding only smooths down the cut sides of what used to be the cell walls. Is the reflectance off the sanded edges of the dead cell walls or off the concave surface of the inner surface of the dead cells and pores?
@ chatomety - I know I'm asking a lot of questions, but by golly, I have them - it's what makes Lil Mikey so charming! Appreciate the time you and your colleagues put into this research and you answering questions. One of the failures of our society is that because we are so loosey-goosey, words have multiple meanings and are therefore at times rendered essentially useless. So this begs the first question for today.
First question this time - Is Reflection = Chatoyance a correct statement? If so, then why the difference in terminology? If not, then what is the difference? It seems to me what is being quantified is the delta in reflectance values off of something in or on wood. Am I in the ballpark?
Second question - Is chatoyance more pronounced in radial, tangential, or transverse planes of presentation?
Third question - since the wood we use is "dead" some for a longer time that others. And what we have left is basically dried up cell walls, have you tested any very freshly cut wood, before the cells have had a time to dry out?
Fourth question - Since when you cut and sand a piece of wood you essentially cut what used to be cells and pores. I suspect for the vast majority of a cut and sanded wood surface, if you magnified it, you would be seeing the insides of what used to be the cells. Take a look as some electron microscope images of wood. Sanding only smooths down the cut sides of what used to be the cell walls. Is the reflectance off the sanded edges of the dead cell walls or off the concave surface of the inner surface of the dead cells and pores?
slightly visible in some rough sawn boards just as they are on the pallets, more visible when sanded smooth as in the small table top i referred to having bought
Food for thought
- Thread Starter Thread Starter
- #79
- Thread Starter Thread Starter
- #80
Technically I think it would be called "Anisotropic Reflectance", so yes, you are right. I've also seen it called "Anisotropic Gloss".
Not seen in transverse plane. That is, you might see some change in appearance, but it does not show the distinctive two-peaked chart (we only tested one sample).
No. We can arrange that.
I don't know.
But I can remark two things that are relevant:
1) brightness has a sharp peak when light is perpendicular to fiber direction
2) chatoyance is higher in latewood for softwoods.
Your questions are very welcome - rather than questions and answers this is a proper positive discussion.