Several months ago I turned this lignum vitae lidded box. The first thing I noticed after completing it was how quickly the wood changed color in the sunlight, going from a just-turned honey brown to a very dark brown in only a couple of hours.

I finished the box's exterior and interior in the same way, going through the grits up to 600 and then finishing with mineral oil and beeswax (or possibly carnauba/beeswax mix, I don't recall).

Now, after three or four months being indoors (on a table by a sunny window), I opened the box to find the inside surface covered in fine, silky white fibers: fine white fibers on inside of box

...as you can see from the photo above, the fibers aren't stuck strongly to the surface and bunch up easily when touched by a finger:

bunched-up fibers

I sometimes finish pieces with 0000 steel wool (but I don't recall finishing this one in that manner), so I held a strong magnet to the fibers to see if they would react, but nothing happened. Here's a closeup of the fibers after I wiped them out with a rag:

macro shot

...from the way the fibers bunch, it seems more like a spider-silk material than a cotton-fiber material, but either way I'm puzzled. Why would this only appear on the inside, and not the outside, of the box? Will it keep growing back after I wipe it away? Has anyone any ideas what might be happening here?

Thanks in advance!

  • If it's not dust from the environment (e.g. dryer lint, fluff from curtain lining), mould? That's all I got. – Graphus Nov 15 '19 at 7:58
  • ...that's just the thing: the box has been closed this whole time, and the fibers are only on the inside(!) I am certain to keep the box closed because that's the intrigue of the piece - the outside receives sunlight and has UV-aged back to the regular dark brown wood color, but the inside has had very little UV exposure, so it's still this unusual honey-brown color... – AKA Nov 15 '19 at 13:03
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    If it is mould, one possible explanation for it being on the inside only is it's sensitive to UV so growing preferentially on the inside because it's dark. This is a total guess, I have no experience with lignum vitae. I did have one further thought yesterday — it's not by any chance wax is it? The colour is off from what you said you might have used (both waxes are yellow, yes? not white like paraffin or microcrystalline wax) but thought it was worth throwing it out there. – Graphus Nov 16 '19 at 7:57
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    OK, I did a test on the tuft that you can see in the last photo - whatever the material is, it's very flammable. It burned quickly, like flash paper, and left a turpene/petroleum smell (ie, no hint of beeswax-smell). My guess would be that the changing weather closed the grain up and thus led to the excretion of my finishing materials (oil and wax). Not sure why this didn't happen on the outside but perhaps since the material seems to be volatile, it evaporated rather than accumulating? – AKA Nov 18 '19 at 17:50
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    These fibres look more like crystalline structures than anything organic. Both paraffin and beeswax contain largish crystals. Though, if the wax has been de-oiled or processed in the right manner those crystals can get really small. Just a guess here, but it looks like the conditions were fine for thin layer of finish to stay wet enough to super-saturate. Once those first crystals were able to grow undisturbed they would have continued as long as the conditions for saturation remained. – jdv Nov 18 '19 at 20:56

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