Ideas for special/magical inks

[Odin's Eyepatch]

I'm playing a 5th level wizard (3.5), and I'm looking for ideas on making my spellbook a bit more "special". I'm aware that you can make your spellbook out of different materials, but there is unfortunately little information about the ink types you could use.

Do people have any ideas (homebrewed or not) on special ink properties, to make your spellbook/writing/scrolls a bit more unique? The closest I've managed to find is the ink created by the "Liquid Night" fundamental (ToM), which makes special glow-in-the-dark ink.

Magical or just alchemical, I don't really mind. Just want to see what sort of ideas you can come up with :smallsmile:

Thanks

[Someone Else DM]

You can use the blood and ash of your enemies to write the spells. Homebrew casting during the writing of the spellbook. Going forward, while preparing your spells from the book, these spells could have the images of your enemies dying from that particular spell (force of the magic missile caving in part of his face, his body bursting into flames from the fireball, the skin pulling in onto the bones as all the moisture is removed from his body from the Horrid Wilting, etc.).

[MaxiDuRaritry]

Use liquid rainbow. (https://youtu.be/hsUGivKETLI?t=672)

Careful, though. It's spicy.

[Doc_Maynot]

IIRC, Cityscape has invisible ink.

[Bohandas]

How about there is no ink, just a permanent illusion

[Inevitability]

How about there is no ink, just a permanent illusion

This may seem solely flavorful, but it's also a great countermeasure against creatures with True Seeing.