posted 10 years ago
What an interesting idea.
I don't know much about acorns, but what you say reminds me of Kakishibu. It's a fermented mix from persimmon that is used to dye fabric, paper, and WOOD. It helps preserve the wood, or so I understand, because of the high tannin content. It interacts with light over time, which causes it to become stronger and darker. I'm not sure what is meant by 'stronger' as it might be a translation issue. Also, antibacterial, antifungal qualities, &c, and so on. Or so I hear from those who have lots of experience working with the medium.
But it's interesting and may be a good starting point to learn about tannin extraction via fermentation.
Another source of information may be medieval inks - I think some of it involved tannin extraction from oak... but the method escapes me.
Good luck with your experiment and let us know how it goes.