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Forum topic by chatometry posted 05-22-2022 02:58 PM 867 views 1 time favorited 17 replies Add to Favorites Watch
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chatometry

9 posts in 42 days


05-22-2022 02:58 PM

Hi everyone
This is Paolo, from the www.chatometry.com team.
I just wanted to share something about what we’ve been doing in the last years. Basically, we identified a reliable method to measure wood chatoyance, which is the way many wood species shift their color depending on the lighting direction.
This is a common example (all pictures show wood sanded to 1500-grit with no finish):

https://www.chatometry.com/home-page/Sapele/

Now the useful info: we put together a summary table based on thousands of samples, showing the typical chatoyance value of many wood species – here:
https://www.chatometry.com/woods/
Each wood can be clicked to reach its specific page, which shows some example of chatoyance on that wood.

I hope these data can actually help some of you :)
Paolo


17 replies so far

View Aj2's profile

Aj2

4492 posts in 3292 days


#1 posted 05-22-2022 03:08 PM

Sapele sure does have a lot of chatoyancy. I once found a board in the lumber rack that was supremely quilted. But there was only one. I know there was only one because I dug through the whole stack looking for another.
Anyone know why Sapele is mostly quarter sawn. I have my suspicions

-- Aj

View controlfreak's profile

controlfreak

3871 posts in 1095 days


#2 posted 05-22-2022 03:19 PM

Sanding to 1500 grit? Shoot me if I ever need that level of smooth.

View Redoak49's profile

Redoak49

5622 posts in 3482 days


#3 posted 05-22-2022 04:32 PM

This is very interesting and the pictures do a good job of showing the effects.

Thanks for posting this !!

While, I would not normally sand to 1500, I would do it on a smaller project to bring out the wood chatoya

Please if you ever get a chance, quartersawn Sycamore would be very interesting.

View BurlyBob's profile

BurlyBob

10786 posts in 3759 days


#4 posted 05-22-2022 06:48 PM

That’s really interesting. I’m going to study that some more this eveing.

View MrWolfe's profile

MrWolfe

1974 posts in 1617 days


#5 posted 05-22-2022 09:05 PM

Great site and thanks for all the hard work.
I’ve bookmarked it for future reference.
Thanks again.

View SMP's profile

SMP

5392 posts in 1399 days


#6 posted 05-22-2022 09:34 PM

I kind of feel like Chris Schwarz about this trend. Was never impressed by purpleheart either:

https://blog.lostartpress.com/2020/11/02/i-dont-like-flashy-wood-go-figure/

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chatometry

9 posts in 42 days


#7 posted 05-22-2022 10:30 PM



Anyone know why Sapele is mostly quarter sawn. I have my suspicions

Maybe they do it to show the ribbon stripe, but then they call it “quartersawn” whenever a ribbon stripe is shown (which doesn’t really need a perfect QS)


Sanding to 1500 grit? Shoot me if I ever need that level of smooth.

I agree – it is never needed. We only use it as a standard way to show chatoyance without finishing. However, in a test we carried out on curly maple, we founs that high-grit sanding provided higher chatoyance, even after finishing:
https://www.chatometry.com/surface-preparation-on-curly-maple/
(as redoak49 also mentioned)


Please if you ever get a chance, quartersawn Sycamore would be very interesting.

Do you mean Platanus spp? We have London Plane here: https://www.chatometry.com/home-page/London-Plane/
Plus you can see some more nice flecks here:
https://www.chatometry.com/what-is-wood-chatoyance/flecks/

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Redoak49

5622 posts in 3482 days


#8 posted 05-23-2022 05:48 PM

Most people are familiar with local names such as Sycamore. I was happy to find you actually had it in your groups. It would be quite helpful if you also provided common names for different areas.

View chatometry's profile

chatometry

9 posts in 42 days


#9 posted 05-23-2022 07:08 PM

That’s true. Adding common names is on the to do list.

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chatometry

9 posts in 42 days


#10 posted 05-27-2022 07:31 AM


I kind of feel like Chris Schwarz about this trend. Was never impressed by purpleheart either:

What drove me to this research was an unfigured Etimoe slab I used a few years ago. No curl, no quilt, nothing. I made a coffee table out of it, and most of the times it just looks dark brown. However, when the sun hits it at the right angle, it completely changes to a bright honey colour, as if it were another piece of furniture.

Figure, like curl, is just revealing a property you can also find (and exploit) in plain wood, as many of the examples shown here:
https://www.chatometry.com/the-pzc-method/scale-1/

or here:
https://www.chatometry.com/the-pzc-method/scale-2/

I hope this provides a different point of view to the subject.

Paolo

View AlanWS's profile

AlanWS

221 posts in 5052 days


#11 posted 05-27-2022 03:13 PM

Thanks for putting this together. The index of refraction of the finish might be an interesting thing to look at with at least one of the types of wood. Rather than finding a lot of finishes, you could simply wet the surface with liquids of different index (mixtures allow small changes) and compare what you see. When you match the index of the wood fibers, you should see a big change in chatoyance. It’s tricky to know what index that would be, since different forms of cellulose have rather different indices of refraction. Only if you find a specific index where it looks particularly interesting would you try to find a finish or mixture of finishes to replicate the effect.

Some of us do like figured wood. People vary in many ways. Chris Schwarz has opinions, as does everyone else. One thing that makes his writing valuable is that he brings up interesting points and describes things clearly enough that you can tell if you agree. In this case I don’t.

-- Alan in Wisconsin

View chatometry's profile

chatometry

9 posts in 42 days


#12 posted 05-27-2022 03:18 PM

Thanks, this is a very interesting idea.
I will try it.
Do you think it is only a matter of refraction index?

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AlanWS

221 posts in 5052 days


#13 posted 05-28-2022 12:30 AM

Other than the color variation in the finish, I think index of refraction of a finish is the main thing that affects the looks, and it even affects the color substantially. When you wet wood with a clear liquid like water it looks darker. That’s because the higher index of the water than air more closely matches that of the wood fibers. This cuts down on the scattered light caused by reflection at each interface, and allows you to see deeper into the wood to the colors present there. The better the index match, the less reflection to interfere with seeing deeper into the wood.

I’m pretty sure that the index of refraction of cellulose fibers depends on direction, so the chatoyance is caused by the variation depending on their direction.

So the effect of the finish is primarily due to index effects. I had not seen chatoyance on a polished unfinished wood surface before your photos, so thank you.

-- Alan in Wisconsin

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chatometry

9 posts in 42 days


#14 posted 05-28-2022 05:18 AM

Thanks Alan

I will see if I can run this test as you suggested. I need two mixable liquids with different refraction index, and which can possibly dry leaving no trace.

Paolo

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Phil32

1802 posts in 1397 days


#15 posted 05-29-2022 04:48 PM

This discussion focused my attention on a piece of basswood I am currently carving. There is a wavy ribbon along the edges of the wood blank (5/4 thick – 15” square – a custom glue-up by Heinecke Wood Products) At first I thought it might be just in the 3” strip they might have added to their standard 12” x 15” plaque, but it appears on all sides.

Basswood chatoyance

-- You know, this site doesn't require woodworking skills, but you should know how to write.

showing 1 through 15 of 17 replies

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