The Hidden Manganese Cave

When I typed “→Bat Cave” into Google Maps, I got a message: “This place may be closed.”
Good. That meant it was the last call to enter the cave before the tourist season opens.

On site, I met with a group charmingly named the Cave Construction Company—a team of enthusiasts who, led by Andrzej Górny, have spent years digging underground corridors in search of new caves, conducting geological and speleological research, and creating inventories of underground formations.

Michał Banaś, a geologist I can confidently call my guide to minerals, had just tipped me off that Andrzej had some ochres for me from this cave, and that he had recently uncovered a rare deposit of black →manganese.
I thought it would be great to see the place where this deposit comes from. Manganese compounds act as natural siccatives for oil paint, which means they speed up the drying of oil.
I was especially curious about the shade of this black pigment, and how transparent it would be in glazes.

“Andrzej, we’ve got a problem—I don’t have a cave helmet or a headlamp…”
“No worries, I’ll lend you mine, I’ve got a spare.”
“Alright, see you Saturday at nine in Bat Cave. Coffee first, then we change and go down.”

Their work reminds me a bit of prison escape movies—the most thrilling moment being when the inmates first feel a draft of fresh air. The difference? These guys move in the opposite direction.

We’re underground. No wind. A steady temperature of 8°C. Water drips from above.
It’s dark, it’s tight, but the target is in sight!
I groan with effort squeezing through narrow cracks.
Completely covered in mud—sorry, clay—we crawl forward until we reach a small cavity filled with black sand.

I bang my helmet on the rocks a few times by accident and my headlamp goes out.
Following my guide’s instructions, I crawl backward or scramble on all fours until we safely reach the spot where we started.
I say goodbye to the rest of the group, still working in other tunnels.
The head of the Cave Construction Company walks me back to my car, and I drive home proud, with a little bag of →black pigment in my hands.

It was one of the darkest days of my life—literally.
Tomorrow I’ll definitely wake up with sore muscles and bruises, but this trip was absolutely worth it!

Back when I wanted to speed up oil drying, the easiest way was to buy a ready-made siccative at the art supply store.
That meant tolerating the smell—like a mix of universal solvent and turpentine.
The old masters had a better solution—they used manganese-rich minerals.
Preserved underpaintings often reveal umbers containing these compounds.

Today, you can buy natural or burnt umber pigment and create a non-toxic siccative right in your studio.
Two or three days—and the paint layer is dry.

That evening, I ground the black sand into pigment.
What I got was a beautiful sepia tone.
I added oil and applied it onto a completely non-absorbent surface (a titanium sheet previously primed with Cremnitz white, which I use for glaze tests).

The sample, applied around 8 p.m., was completely dry by 3 p.m. the next day!