Finish vs Chatoyance experiments

[chatometry]

was trying to give you a reference to measure it in different stages from 1 to stage 3. From flat book-matched, to carved staged to a clear coat finish stage. I wanted to see how much the chatoyance value changes (or it doesn’t).

I am sure the value would increase. If we can consider carving similar to veneer cutting there is data, and the there is data for finished veneer. Stage 1, i.e. rough cut boards, depends on the quality of the cut. A very rough cut would not show any chatoyance at all...

As far dimensional stability, it is much preferred due to stiffness and rigidity and for tensile strength. Take a 36” x 4” x 1” thick of maple that is a quarter sawn and a second piece that is flat sawn cut. Have cylinder blocks present from point A to point B. Set each piece about 4” or so overlapping the cylinder blocks. You can step on the middle at your own risk or put iron weights. You will see how one grain orientation would have a lot more flex than the other.

This is interesting. Do you know if there's any data available about this? Also, considering that you mention different tap tones, what is violin back standard? Flat or quarterd?

Anyway, also from what Frank was saying, it appears "common knowledge" that a carved (or planed os scraped) surface would be more chatoyant than the same surface when sanded. I wish I had more skill with such tools, then I could try.

the quarter sawn side edge has higher chatoyance to my eye

Do they have the same surface quality? I would guess the flat face is planed while the side is cut in a different way...?
Also, do you know if the fibers are ondulated on the flat surface or on the quartered surface? That is, what happened in this log: A or B?


source: [Beals and Davis 1977]

Whether waves run side to side or in and out of the surface changes the relative position of the brightness peaks, so altering the way curl is perceived.
What I mean is visible in these two gifs below. Bear in mind that the light rotates around a vertical axis (perpendicular to the surface), performing a 360° rotation. Whatever happens in gif 1, it appears to be happening twice in the cycle. Differently, in gif 2 there is an evident asimmetry in the chatoyance cycle (curl is way more evident when the light goes from 9:00 to 3:00 than from 3:00 to 9:00).



So many variables

Thanks everyone for providing so much insight on this topic!!

 

[Arn213]

This is interesting. Do you know if there's any data available about this? Also, considering that you mention different tap tones, what is violin back standard? Flat or quarterd?

There actually data available- see below. The one I mentioned you can easily do that test with materials I mentioned. Violin back are usually quarter sawn cut.


Guitar neck stability and stiffness test
https://leonardo-guitar-research.com/Guitar_neck_stability_and_stiffness_tests.pdf


Mechanical properties of wood
https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf

Guitar neck tension and compression

This photo below has been an inspiring image that has led many other companies and small luthiers to follow suit in order to show that their necks are strong and stable.

 

[Arn213]

Do they have the same surface quality? I would guess the flat face is planed while the side is cut in a different way...?
Also, do you know if the fibers are ondulated on the flat surface or on the quartered surface? That is, what happened in this log: A or B?

The flat sawn face was surfaced planed- the side edge had a light pass on the jointer, hence why you can see some saw marks remnant. That violin amber or that light honey color is from the side edge being exposed to natural light.

Also, do you know if the fibers are ondulated on the flat surface or on the quartered surface? That is, what happened in this log: A or B?

View attachment 220449
source: [Beals and Davis 1977]

It would be option “B”.

 

[FLQuacker]

Great reading and links.

 

[chatometry]

Guitar neck stability and stiffness test
https://leonardo-guitar-research.com/Guitar_neck_stability_and_stiffness_tests.pdf

Interesting. As you suggested, they found better performances on flatsawn.

Mechanical properties of wood
https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf

I knew this document, very nice, I used it for some structural design.

This photo below has been an inspiring image that has led many other companies and small luthiers to follow suit in order to show that their necks are strong and stable.

Nice shows of strength... I am more impressed by the deflection than by the strength itself. I still wonder if curl affects strength, speed of sound, etc...
With the technique we are using to measure chatoyance we should (theoretically) be able to detect 3d fiber directions.

It would be option “B”.

So the qs side has fibers that go in and out of the surface, while the fs has fibers that go from side to side. I wonder how this is compatible with broken curl...

Thanks for replying my many questions!
We are thinking about a research to quantify curl (meaning 3d fiber waviness) and to correlate it to sound properties...

 

[chatometry]

Samples for next step...

 

[Arn213]

Nice shows of strength... I am more impressed by the deflection than by the strength itself. I still wonder if curl affects strength, speed of sound, etc...
With the technique we are using to measure chatoyance we should (theoretically) be able to detect 3d fiber directions.

In luthierie particularly, figuring does affect strength and it is less dimensionally stable.
Several ways to strengthen (make it more rigid) it is to add carbon fiber rods or use lamination technique instead of one piece construction. A luthier friend of mine has told me that figured wood is lighter in weight compared to non figured woods.

I am interested what instrument and process you will use to measure speed of sound (figuring and non figured types). A Lucchi meter does measure the velocity of sound and interestingly if you had say a 6” wide piece- the reading closest to the center of the tree would have a slightly higher reading to the reading away from the center of the tree. The Lucchi meter is used to get a velocity reading on violin bows (Brazilian Pernambuco/Brazilwood)- the higher the rating, the higher the velocity of sound………it cost a lot more too.

 

[chatometry]

I am interested what instrument and process you will use to measure speed of sound (figuring and non figured types).

No idea yet... I see these Lucchi meters are quite expensive... Maybe measuring natural frequencies / tap tones could be easier...?

 

[2feathers Creative Making]

No idea yet... I see these Lucchi meters are quite expensive... Maybe measuring natural frequencies / tap tones could be easier...?

Reverb.com had one for 700 with free shipping recently

 

[Arn213]

Reverb.com had one for 700 with free shipping recently

Exercise with clear caution. First off read through it carefully. Price is too good to be true. He doesn’t seem to be the original owner and if he was he will tell you first hand how it works and what the actual condition it is in- excellent means nothing as that comes from optics. Does it function and calibrated to work properly? Question how old is it and has it been dropped. Red flag- it doesn’t show powered up and he doesn’t have an example of a reading on a piece of wood. If he knew how to use it or have owned it, he would have two separate reading east and west.

This site used to be a good platform site, until it was purchased by a conglomerate. Bad customer support and bad reviews since from musicians- don’t ask me how I know. You think they will side with buyers when things go wrong. Also, US sellers don’t have good protection when an international buyer pays via PayPal. Unfortunately Italy (sorry Paolo) don’t have good standings with international shipping from the US. One place I will not ship and it has to do with their lax on their own postal system.

There is a reason there is only 1 watcher on this item. Fair warning and caveat emptor!!!

 

[2feathers Creative Making]

As a cheaper alternative, have you seen the conversation on maestronet.com called 'ridiculously easy way to measure speed of sound' ? It outlines a system and mechanism for measuring sound quality in wood that uses about 15 to 20 dollars worth of equipment and free software . Read through the entire conversation! The key to consistent readings is discussed further into the conversation.

 

[chatometry]

Thanks everyone for these suggestions. When we start this set of experiments we'll start from here.

Going back a few posts...

Especially on certain grain patterns that tend to capture the super fine sanding dust in the grain and cause a noticeable change in chatoyance.

How would you clean this sort of "dust clogging"? We can test before and after cleaning and see if there's a difference. And what species did you have in mind?

 

[Arn213]

As a cheaper alternative, have you seen the conversation on maestronet.com called 'ridiculously easy way to measure speed of sound' ? It outlines a system and mechanism for measuring sound quality in wood that uses about 15 to 20 dollars worth of equipment and free software . Read through the entire conversation! The key to consistent readings is discussed further into the conversation.

Yes, there are other options outside of the Lucchi meter that is a DYI/homebrew. Paolo @chatometry , here is another option that is a lot, lot more inexpensive and financially more accessible-link below that is pretty thorough that has the ingredients that you need, walks you through, has visuals and actual test on species:

Sound velocity

A simple method to measure sound velocity / radiation ratio in soundboard wood based on the longitudinal resonance frequency

www.cvhgitaren.com

 

[chatometry]

Interesting, thank you!
Such a simple material (wood), yet still so many secrets to be unveiled...

 

[2feathers Creative Making]

Yes, there are other options outside of the Lucchi meter that is a DYI/homebrew. Paolo @chatometry , here is another option that is a lot, lot more inexpensive and financially more accessible-link below that is pretty thorough that has the ingredients that you need, walks you through, has visuals and actual test on species:

Sound velocity

A simple method to measure sound velocity / radiation ratio in soundboard wood based on the longitudinal resonance frequency

www.cvhgitaren.com

That is a better compilation of the facts in the conversation which I was referencing. I figured you might be able to tell us more and you did not disappoint. Thanks. I am good at finding random facts. You are much better at finding specific facts especially when it relates to musical instruments and wood/sound relationships.
I am not a sound man, nor an instrument maker. I am an eclectic collector of useless and semi-useless facts which have absolutely no relevance to my own work or hobbies.... I have an 8th grade education but taught school. I have several papers to paste on a wall but don't have enough wall space in the bathroom to hang them where they are serviceable...
I enjoy great designs and produce rough, live edge furnishings. Go figure.
Anywho... great read. Glad you were able to find the info compiled so our friends didn't have to sort that out of the conversation on maestronet.

 

[2feathers Creative Making]

Thanks everyone for these suggestions. When we start this set of experiments we'll start from here.

Going back a few posts...

How would you clean this sort of "dust clogging"? We can test before and after cleaning and see if there's a difference. And what species did you have in mind?

Possibly high vacuum or alcohol wipe, I tend to just switch to a sharp edge if it looks like the board is loading with dust. Oak, ash,and other open pore woods are what I was thinking about. But the exotics that are oily and open pore would be even harder to clean, I would think

 

[chatometry]

Possibly high vacuum or alcohol wipe, I tend to just switch to a sharp edge if it looks like the board is loading with dust. Oak, ash,and other open pore woods are what I was thinking about.

I cut three euro ash samples - usual sanding up to 1500-grit - and submitted them to PZC measurement.
Then I cleaned one with water, one with alcohol and one with acetone, and had them measured again (after they dried).
The results are...



I don't know what actually happens, but it looks like alcohol improved chatoyance.
This is the alcohol-treated sample, before and after cleaning. The difference is not very evident, but still maybe an alcohol wipe before finishing could be something worth testing...


Before


After

 

[chatometry]

We had some open points, for which now some data is available.
We tested alcohol cleaning on Curly maple, and results are negative (differently from those preliminary tests on ash...)
In addition, we compared as received (veneer), rough sanding (240-grit) and fine sanding (1500-grit); as expected, the best results are achieved on veneer as received, but it was interesting to see that (even after finishing) fine-sanded surfaces appeared more chatoyant than rough sanded ones.
Finally, @Arn213 we eventually managed to test nitrocellulose lacquer (on as-received veneer), but the results are worse than using BLO or shellac.

This page provides more details:

Surface preparation on Curly Maple – PZC Chatometry

www.chatometry.com

 

[Arn213]

I truly appreciate your test and data Paolo. Thank you. Nitrocellulose lacquer comes in different forms and mixed in different forms. You have NC where it is based on 50’s ingredients and NC where it has more contemporary ingredients. A lot of that ingredient is “proprietary” to a company or a luthier. It is porous for a reason for musical instruments and it is “flexible” again for a reason. Each luthier also has their own “proprietary” way of applying this “thinner skin” finish and the thickness is set to some form in “mm” thickness. There is also prep. work to the wood and whatever pore filing and/or sanding sealer required before these layers of top coats are applied with light wet sanding in between with high grit, then it gets buffed with a polishing compound with a buffing machine, then lastly it has to fully cure so it gets hard (sometimes it can take a month). Those necessary steps are required to have optimized finish quality that helps enhance figuring and chatoyance.

I also realized that the NC in your test was only 2 coats applied and the other finishes had 3 or 4. Is there a reasoning for that and should the “thickness” of the finish and how much applied should be even across the board to have “truer” outcome? What brand or NC did you use or was it custom mixed? It is actually difficult to obtain NC in Europe. There is mediocre NC and there is good NC- that goes for anything else.

Would like to see a test video perform on the NC included in the data.

Would you be inclined to try an alternative to add another finish on your test that is a derivative of solid shellac application? If you are so inclined cut the shellac form of it’s 100% to get it thinner, to flow better and should help enhance figuring depth as well as chatoyance. Mix 60% clear shellac to 40% denature alcohol or 65% to 35% ratio. 4 coats. No wet sanding in between. I would be curious what the numbers are.

 

[chatometry]

I used a Nitorlack spray NL [bad service!], I just sprayed it on my samples, with no sanding in between (that's another thing to explore). Also, on non-sanded samples the surface is not smooth, yet chatoyance is higher. So I wonder if sanding between coats actually helps chatoyance. Clearly, there are a lot of objectives when finishing: smooth surface, feel, scratch resistance, etc, while I am ONLY focusing on chatoyance.

The reason why you only see two coats with NL is that results from the second coat are very similar to those after the first coat, so they were considered stabilized.

I am happy to carry out tests as per your suggestions, but in this case shellac was already tested in three different cuts, as follows:

Blonde Dewaxed Shellac “Light” (1 part in 13 parts of Alcohol)
Blonde Dewaxed Shellac “Medium” (2 parts in 13 parts of Alcohol)
Blonde Dewaxed Shellac “Dense” (4 part in 13 parts of Alcohol)

(I should have the website updated to provide this info)

Do you think we should test an even lighter shellac?

Anyway, thanks for being always so helpful!
Paolo