why do rosewoods darken?

[chas]

The title says it all. All the members of the rosewood family (at least all those common for flutes: blackwood and cocobolo most notably) darken with age. I've asked a couple of makers, and they say there's no way to stop the process, although a real finish like laquer or uretane will evidently slow it.

So does anyone know the chemistry of it? Is it due to UV or oxidation? Neither of the above?

TIA

[Congratulations]

Is it only rosewoods that darken? Because boxwood and gidgee and cocus all also darken with age.

I'm interested in why they do this, as well.

[Unseen122]

Actually Cocus is in the Rosewood family. Mopane (also a Rosewood) does this it is probably oxidization. Maybe Terry, Jon, or David can help us out with this one.

[Congratulations]

Actually Cocus is in the Rosewood family.

[Sillydill]

I believe it is due to oxidation! I have no documentation of this.

:roll: But, I've been adding Coconut Oil to my Almond Oil. It really brings out the color in brown or reddish woods. My hypothesis is the Coconut Oil oxidizes the surface of the wood and brings out the darker colors.

Keep Makin Music!

Jordan

[Lambchop]

I'd be willing to bet it's due to some kind of chemical process. Yup.

[chas]

Is it only rosewoods that darken? Because boxwood and gidgee and cocus all also darken with age.

I'm interested in why they do this, as well.

Boxwood does darken with age, but VERY slowly. Most of those rich brown boxwood flutes from the days of yore were darkened with acid; my five-year-old boxwood flute has darkened noticeably where my lip touches it (acid sweat), but is really just the tiniest bit darker than when I got it. My six-month-old cocobolo flute had gone from a fiery red in just aboout any light to having to be under bright light to see its grain. Which is a real bummer, 'cause that was one gorgeous flute.

Actually Cocus is in the Rosewood family. Mopane (also a Rosewood) does this it is probably oxidization. Maybe Terry, Jon, or David can help us out with this one.

I thought the rosewoods were a genus -- Dalbergia. Cocus is genus Brya.

I had always thought it was oxidation, but oiling with a really vitamin E rich oil solution doesn't do anything. Probably a few drops of vitamin E over the surface every couple of weeks isn't enough to stop it, though.

[Casey Burns]

Actually Cocus is in the Rosewood family. Mopane (also a Rosewood) does this it is probably oxidization.

Cocus is related to Poison Oak and Cashews. Not in the Leguminosae.

Mopane (Colosphernum mopane) is a legume, but definitely not a rosewood (Dalbergia sp.).

Oxidation of the outside surface is one reason why woods darken with age. Also, UV exposure. Oiling also darkens wood. There are oxidation inhibiting UV blocking finishes that are appropriate on stringed instruments but not practical on woodwinds - since the wood needs to be oiled.

Casey

[sturob]

Cocus is related to Poison Oak and Cashews. Not in the Leguminosae.

That's incorrect, Casey; cocus is also a legume. Brya ebenus is in the family Fabaceae, the peas/legumes, just like all Dalbergia spp. Fabaceae is a synonym of Leguminosae and is, I think, the more current term.

Ebony, not cocus, is the outlier: it's in a different subclass.

Cf this thread.

Stuart

[Casey Burns]

I guess I need to update my hardwood botanical taxonomy!!! I wonder how Cocus, Mopane and Rosewoods are related - if they are in the same or different subfamilies - or how distant or closely related they are via DNA studies, etc. <see citation below>

These peas and beans have various toxicities - Cocus is quite notorious, and according to some literature I read at a hazardous material library 15 years ago it shares many of the same sensitizers as poison oak, and at the time was considered in the same family. The articles I read were probably themselves published much earlier.

The Linnean system of taxonomy is fraught with all sorts of traps and pitfalls and homologies and synonomies that require several lifetimes of taxonomists to resolve. There are new methods such as Cladistics, DNA sequencing, etc. that are now being applied to further confuse or resolve these issues. Its worse for botany than for the fossils I work with. What defines a modern species when some can interbreed with fertile offspring? What is a family except for a grouping label? It gets more confusing when they add supra- and sub- families, tribes, etc... The genus label seems about the most robust aspect in most taxonomies (I know this through working with various taxonomists in my paleontology work) and some taxonomists are lumpers, grouping everything together (I am one of these) versus splitters who name new species or higher groupings etc. based on sometimes the flimsiest of criteria. I know of one species of fossil sand dollar in California that at one time was split into about 41 species!

Dalbergia and Colophospermum (correct spelling, sorry!) seem rather robust constructions for now though I sometimes ponder the differences between the old and new world Dalbergias, seeing as how they have had most of the Cenozoic to diverge, but like Metasequoia, is a fairly conservative group evolution-wise. Apparently this is being explored and it looks like Cocus (Bryinae) is now considered part of this subgroup, if I read the citation below correctly.

Mopane is considered in the Caesalpinoideae, not mentioned in the listing below of the Dabergieaea although this might be in a subgrouping. Other genus names for Mopane include Hardwickia (I like this one - one of my favorite hardware stores in Seattle is called Hardwick's) and Copaifera.

Something to explore in my spare time (what spare time? I am too busy making flutes and would rather leave taxonomy for the taxonomists!). But it is interesting.... In a little bit of exploring I found out we had Dalbergia growing in the eastern US, and possibly out here (who knows: we even had Bananas in the Pacific NW according to an old friend of mine who is now a paleoboatnist at Florida State) in the Cretaceous when all of these Rosewood growing regions were connected together.

Casey

see http://www.botany.org/ajb/00029122_di015084.php

The Dalbergioid Legumes (Fabaceae): Delimitation of a Pantropical Monophyletic Clade, 503-533

Matt Lavin, R. Toby Pennington, Bente B. Klitgaard, Janet I. Sprent, Haroldo Cavalcante de Lima, Peter E. Gasson

Abstract: A monophyletic pantropical group of papilionoid legumes, here referred to as the "dalbergioid" legumes, is circumscribed to include all genera previously referred to the tribes Aeschynomeneae and Adesmieae, the subtribe Bryinae of the Desmodieae, and tribe Dalbergieae except Andira. Hymenolobium. Vatairea. and Vataireopsis. This previously undetected group was discovered with phylogenetic analysis of DNA sequences from the chloroplast trnK (including matK) and trnL introns, and the nuclear ribosomal 5.8S and flanking internal transcribed spacers 1 and 2. All dalbergioids belong to one of three well-supported subclades, the Adesmia, Dalbergia, and Pterocarpus clades. The dalbergioid clade and its three main subclades are cryptic in the sense that they are genetically distinct but poorly, if at all, distinguished by nonmolecular data. Traditionally important taxonomic characters, such as arborescent habit, free stamens, and lomented pods, do not provide support for the major clades identified by the molecular analysis. Short shoots, glandular-based trichomes, bilabiate calyces, and aeschynomenoid root nodules, in contrast, are better indicators of relationship at this hierarchical level. The discovery of the dalbergioid clade prompted a re-analysis of root nodule structure and the subsequent finding that the aeschynomenoid root nodule is synapomorphic for the dalbergioids.

[Aerowhip]

Abstract: A monophyletic pantropical group of papilionoid legumes, here referred to as the "dalbergioid" legumes, is circumscribed to include all genera previously referred to the tribes Aeschynomeneae and Adesmieae, the subtribe Bryinae of the Desmodieae, and tribe Dalbergieae except Andira. Hymenolobium. Vatairea. and Vataireopsis. This previously undetected group was discovered with phylogenetic analysis of DNA sequences from the chloroplast trnK (including matK) and trnL introns, and the nuclear ribosomal 5.8S and flanking internal transcribed spacers 1 and 2. All dalbergioids belong to one of three well-supported subclades, the Adesmia, Dalbergia, and Pterocarpus clades. The dalbergioid clade and its three main subclades are cryptic in the sense that they are genetically distinct but poorly, if at all, distinguished by nonmolecular data. Traditionally important taxonomic characters, such as arborescent habit, free stamens, and lomented pods, do not provide support for the major clades identified by the molecular analysis. Short shoots, glandular-based trichomes, bilabiate calyces, and aeschynomenoid root nodules, in contrast, are better indicators of relationship at this hierarchical level. The discovery of the dalbergioid clade prompted a re-analysis of root nodule structure and the subsequent finding that the aeschynomenoid root nodule is synapomorphic for the dalbergioids.

God I love it when taxonomists talk dirty.

[jim stone]

Legumes, eh? this explains why I want to eat flutes.

Mopane. Yum!

[Tyler]

From my experience with woodworking, building mandos, etc., I have found that oxidation does cause a great deal of darkening in a lot of woods that i have worked with...In the woodworking business folks often choose woods that will darken on purpose to obtain a certain look. In instrument building I know that people make wood selection based upon the tonality they are looking for as well as looks or visual style...Harder woods resonate lower tones while softer woods resonate higher tones. When I build a mando I usually use spruce for tops and maple for back and sides, but have experimented in harder and softer woods for fun (layered pine top with oak back and sides.....interesting experiment to say the least, but uuuglier than sin.)
Anyways, to say what I was trying to get at in the first place , I've noticed that all woods darken with age, but some darken faster than others...and again i think that is oxidation, but I might be wrong...and I also think that the harder the wood, the more it might darken with age, but again, I could very well be mestaken...
I'd have to ask the old man, he's the professional woodworker in our family.

[Screeeech!!!]

Hi all, i found this snippet of info...

From http://www.pcimag.com/CDA/ArticleInform ... 92,00.html

Transparent systems that allow the natural features of wood - including color, grain and texture - to remain visible are attracting interest and demand for them has been increasing. However, the long-term instability of such transparent systems in outdoor applications has so far seriously hindered them from becoming more widespread. The main reason for this instability is the UV light transparency of the topcoats and the extreme sensitivity of certain wood components, particularly lignin, to UV light degradation. Even in indoor diffuse light conditions, naturally pale wood tends to yellow and darken with time as a result of lignin photo-oxidation.