UVF Wood

[Adrian]

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

[JMC]

That's really funky Adrian. I wonder if it is to do with fungi in part of the wood?

[JCDowdy]

Lignins are known to be fluorescent. There doubtless other fluorophores.

 

I did not know this was commonly used to distinguish wood species, nice demonstration.

[Adrian]

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.

[Andy Perrin]

That is very striking. I love the colors here.

[OlDoinyo]

The distinction in the second sample seems to be between sapwood and heartwood.

[eye4invisible]

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.

[Andy Perrin]

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.

[Andrea B.]

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?

[eye4invisible]

...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.

[Andrea B.]

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.)

[ulf]

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.