Guys,
I can now say that Obsidian Oil does what mineral oil cannot do.
Here is a picture of the stems I just deoxidized with the Ibepens product,
after being thoroughly rubbed down with lots of mineral oil:
And here they are after being subsequently wiped down with Obsidian Oil:
These phone pics in poor basement lighting do not begin to do justice to the difference. So, if you cannot tell, the blackness of the post-Obsidian Oil stems is magnificently deeper and richer. Remarkably "blacker."
Here's a fascinating thing: The Obsidian Oil is not tinted black! It's not tinted at all. I had just assumed that it would be black. But this clear substance leaves the stems looking like... well, obsidian.
It also smells marvelous. Maybe something in the sweet-spice family? Or an exotic, near-Eastern anointing oil. One of the magi may have brought a vial of this to the first Epiphany.
If you like what mineral oil does to your stems, you'll love what Obsidian Oil does!