Very interesting article: identifying wood species by Fluorescence

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mick

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I stumbled across article this morning. I never knew this existed but it's a great read. I apologize for the format but it would let me share so I had to copy and paste so the word list is in paragraph form.

FLUORESCENCE: A SECRET WEAPON IN WOOD IDENTIFICATION

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by Eric Meier
While certain woods can appear basically identical to one another under normal lighting conditions, when exposed to certain wavelengths—such as those found in blacklights, (which are mostly invisible to the naked eye)—the wood will absorb and emit light in a different (visible) wavelength. This phenomenon is known as fluorescence, and certain woods can be distinguished by the presence or absence of their fluorescent qualities.
One of the best examples of fluorescence is found in Black Locust (Robinia pseudoacacia), which is very similar to Mulberry (Morus spp.) in both appearance and weight. But one way to easily distinguish the two is by observing them under a blacklight; Black Locust will emit a strong yellow-green glow, while Mulberry will be non-reactive.
The process of detecting fluorescence in wood samples need not be intimidating or limited to the scientific community—blacklight bulbs are available in many hardware stores for only a few dollars and can be used in standard lamp sockets. (These bulbs should never be confused with germicidal ultraviolet bulbs such as those used in UV sterilizers, which emit UVB or UVC light, which can pose serious problems.
Even though the process of detecting fluorescence is very simple, a few suggestions will help to maximize the effect and make the identification process as reliable as possible:

Buy the brightest (highest wattage) blacklight available.

Freshly sand/expose the wood grain before testing: this can be critical in detecting fluorescence in some woods.

Turn out all other lights for the clearest detection of fluorescence.

Be careful not to mistake simple reflections or illumination of the wood surface for fluorescence: the wood should literally glow.

The most common colors of fluorescence are green and yellow, but some woods can fluoresce orange, pink, red, etc.

While some species will give a strong fluorescent response, many others will only be faintly fluorescent, while the majority of species will exhibit no fluorescence at all.

Species that are shown to produce a fluorescent response may still vary from piece to piece in the color and intensity of the fluorescence.

Here is a list of woods that exhibit some level of fluorescent properties when exposed to a black light:
Wood SpeciesFluorescence notes:Afzeliafaint to medium yellow-green; dependent on speciesAlbiziabright, uniform greenAmendoimbright streaks of yellowAraracangamedium uniform yellow/greenAvodirefaint to medium streaks of yellow/greenBlackwood, Australianmedium streaks of yellow/greenBloodwoodfaint to medium uniform blue; not always apparent in wood, but vivid in ethanol extractBubingafaint to medium yellow/green; not always presentBuckthornmedium uniform greenCamelthornmedium uniform greenCanarywoodfaint to medium yellow streaksCebilmedium to bright streaks of green; surrounding dark areas in heartwoodChechenmedium to bright streaks of greenCoffeetreebright uniform yellow/greenCumarufaint to medium green streaksEbony, Texasmedium uniform yellow/gold; not always presentElm, Wychfaint to medium yellow/green streaks; not always presentEspavefaint to medium yellow/green streaks; not always presentGidgeemedium to bright uniform greenGoncalo Alvesfaint to medium streaks of yellow/green; not always presentGreenheartfaint to medium uniform greenGuanacastemedium uniform yellow/goldGuatambufaint to medium streaks of yellow/greenHububallimedium to bright streaks of greenIronwood, Blackfaint yellow/green streaks; not always presentIronwood, Desertfaint yellow streaksJatobafaint to medium yellow/orangeKoamedium to bright streaks of green; not always presentKopiefaint uniform yellow/green; not always presentLancewoodfaint to medium green streaks (not present in sapwood)Lebbeckbright, uniform yellow/greenLemonwood, Africanfaint to medium yellow/greenLocust, Blackbright, uniform greenLocust, Honeybright, uniform greenLocust, Waterbright, uniform greenMachichemedium, uniform greenMahogany, Santosfaint to medium green streaksMangiummedium to bright streaks of yellow/green; not always presentMangobright green streaks in certain portions of heartwoodMerbaumedium, uniform green, with bright yellow/green streaks in areas of mineral depositsMesquitefaint to medium green streaks, dependent on speciesMimosamedium green streaksMonkeypodfaint to medium yellow/green streaksMonkeythornmedium to bright streaks of yellow/greenMopanefaint to medium yellow/green; not always presentMuningafaint to medium yellow/orange; not always presentMyrtlebright yellow/green streaks in certain portions of heartwoodNarra/Amboynamedium yellowOlivefaint to medium yellow streaks in certain portions of heartwoodOlive, Russianmedium uniform greenOpepefaint to medium yellow/greenOrangefaint to medium yellow streaksPadauk, Africanfaint to medium yellow/orangePanga Pangafaint uniform yellow/green; not always presentPartridgewood (Andira spp.)faint yellow streaks; not always presentPeroba Rosamedium uniform yellow/greenPink Ivorymedium streaked pink/red in certain portions of heartwoodPiquia Amarellobright, uniform yellowPistachiobright, uniform greenPurpleheartfaint to medium yellow/orange streaks; varies by speciesQuebrachofaint green streaksQuinafaint to medium uniform yellow/greenRaspberry Jamfaint to medium uniform yellow/green in heartwood, with bright streak at sapwood/heartwood transitionRedbud, Easternmedium green streaksRedheartmedium uniform orangeRengasfaint to medium uniform yellow/orangeSassafras, Blackheartmedium orange/red streaks in colored heartwood areasSatinwood, East Indianfaint to medium yellow streaksSatinwood, West Indianfaint to medium yellow streaksSugifaint uniform pink/redSumac, Staghornmedium to bright streaks of greenTalibright uniform yellow/goldTimboranafaint to medium green greenTornillomedium uniform yellow/greenT’zalamfaint to medium uniform greenWitelsfaint to medium uniform yellowYellowheartfaint to medium uniform yellow


WATER EXTRACT FLUORESCENCE

Also, another trick to do with a blacklight is what is called water extract fluorescence and ethanol (alcohol) extract fluorescence. Some woods, while they don’t physically fluoresce under a blacklight, will have very bright reactions when wood shavings and/or sawdust is mixed in a small vial or other clear container and held up to a blacklight.
An excellent example of this is Wenge: the wood doesn’t fluoresce, but something as simple as wiping the surface with denatured alcohol will serve to draw out and concentrate the heartwood extractives, and reveal a bright green fluorescence. The proper way to test for this is to take some small shavings (or sawdust) and place them in a small glass vial with either water (for a water-extract test), or denatured alcohol (for an ethanol-extract test).
Alcohol typically results in faster, more vivid, extract fluorescence than using simply water, but water extract tests can be useful when some woods are known to not produce a water-extract fluorescence color, such as Brazilian Rosewood.
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Dehn0045

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wood database and hobbithouseinc are my two go-to websites for wood identification. lots of interesting stuff for a wood junkie!
 

sorcerertd

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wood database and hobbithouseinc are my two go-to websites for wood identification. lots of interesting stuff for a wood junkie!
Totally agree.

One thing I notice about fluorescence is that the CA seems to glow, so ID'ing wood after it's finished can be misleading. It is cool, though. This is purpleheart under a (supposedly) 365nm light.
3489d889c8cf47ac562bde609a6e09e9.jpg


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