Adrian Posted November 19, 2018 Share Posted November 19, 2018 Whilst researching possible new subjects for UV fluorescence, I came across the fact that different woods may fluoresce different colours. Wood turners make use of this to help distinguish and identify different species e.g. Mulberry and Black Locust wood look and feel very similar, but Black Locust fluoresces a bright yellow colour.I have tried another couple recently with interesting results. The first is a vase turned from spalted English Elm (Ulmus procera), which shows interesting yellow streaks in the wood.The second is a section through Honey Locust (Gleditsia triacanthos) wood. Would anyone know what causes the yellow streaks?Technical specs:Nikon D800 with 105mm micro Nikkor. Both subjects "light painted" with Convoy S2+ UV torch. Approx 15 seconds at f/11 Link to comment
JMC Posted November 19, 2018 Share Posted November 19, 2018 That's really funky Adrian. I wonder if it is to do with fungi in part of the wood? Link to comment
JCDowdy Posted November 19, 2018 Share Posted November 19, 2018 Lignins are known to be fluorescent. There doubtless other fluorophores. I did not know this was commonly used to distinguish wood species, nice demonstration. Link to comment
Adrian Posted November 19, 2018 Author Share Posted November 19, 2018 There is an interesting article here: https://www.wood-dat...identification/I think it is more likely lignin than fungus, as the fungus in Elm (White Rot) shows up as black marks on the visible record, and does not coincide with the UV record. Link to comment
Andy Perrin Posted November 19, 2018 Share Posted November 19, 2018 That is very striking. I love the colors here. Link to comment
OlDoinyo Posted November 19, 2018 Share Posted November 19, 2018 The distinction in the second sample seems to be between sapwood and heartwood. Link to comment
eye4invisible Posted November 19, 2018 Share Posted November 19, 2018 Very interesting study. What's also suprising (at least to me) is that whatever varnish or polish that was used on the wood vase did not seem to make a difference to the fluoresced colours in the untreated wood. Link to comment
Andy Perrin Posted November 20, 2018 Share Posted November 20, 2018 What's also suprising (at least to me) is that whatever varnish or polish that was used on the wood vase did not seem to make a difference to the fluoresced colours in the untreated wood....see, I would take that as an indication that there wasn't any varnish or polish applied. I assume it's just sanded well. Link to comment
Andrea B. Posted November 20, 2018 Share Posted November 20, 2018 Do tannins fluoresce? Could the yellow be from that? Or maybe flavonoids? The cross section fluorescence is quite dramatic. IIRC, lignin causes the blue fluorescence? Link to comment
eye4invisible Posted November 21, 2018 Share Posted November 21, 2018 ...see, I would take that as an indication that there wasn't any varnish or polish applied. I assume it's just sanded well.It's possible, but there appears to be a bit of a shine to the vase in the visible spectrum. Link to comment
Andrea B. Posted November 22, 2018 Share Posted November 22, 2018 Some woods can be sanded to a shine. I have some teak salad bowls, for example. And a couple of other "shiny" wooden bowls, but I don't know what their wood is. The husband sitting here at the breakfast table says he thinks wood with high oil content (like teak) will take a shine. (I don't have time to look this up today.) Link to comment
ulf Posted November 22, 2018 Share Posted November 22, 2018 Some woods can be sanded to a shine. I have some teak salad bowls, for example. And a couple of other "shiny" wooden bowls, but I don't know what their wood is. The husband sitting here at the breakfast table says he thinks wood with high oil content (like teak) will take a shine. (I don't have time to look this up today.)I believe your husband is right.I also think that dense compact wood-types with few micro channels will be suitable candidates to get shiny.I'll ask a friend that has worked as a fine carpenter in his youth if he can add something to this. Link to comment
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