Lichen Glaze & Copper: The Alchemy of Atmospheric Firing

In the world of ceramics, the firing process is often as much about relinquishing control as it is about tightly controlled precision. Most ceramics you encounter are fired in electric kilns—essentially giant toaster ovens—where the only variables you can affect are time and temperature. But in our studio, we embrace a different method, one that invites a bit of controlled chaos into the process. I invite you to nerd out with me on what I find to be a fascinating process: atmospheric firing.

A Dance of Elements in the Kiln

Unlike an electric kiln, which offers a predictable environment, our natural gas kiln allows us to manipulate the atmosphere within, creating a microclimate that influences the final outcome of each piece. This means we control not just temperature but also pressure, the specific ratios of oxygen & carbon flying throughout the kiln,  and the chemical interactions occurring  between this atmosphere and our glazes at a molecular level.

Glazes aren’t like paint—they don’t simply stay the color they appear in their raw state. Instead, they undergo complex transformations, responding to the specific conditions we set in the kiln. One of our most fascinating glazes, aptly named Lichen, epitomizes this beautifully.

The Magic of Lichen Glaze

Lichen glaze is, in essence, an extension of nature itself. Just like lichen in the wild—a form of symbiotic life with infinite variations—this glaze exhibits a broad spectrum of colors and textures. Its base is our classic white Meringue glaze recipe with copper added to it, but how it develops in the kiln is where the alchemy happens.

Picture a row of shiny new copper saucepans hanging above the stove in a classic french kitchen. Now picture The Statue of Liberty with it’s beautiful matte green patina. Both are made of the same exact element. 100% Copper. Lady Liberty in fact, used to have the same gleaming finish as that row of copper pots, but Father Time and Mother Nature slowly oxidized its surface, leaving behind the iconic green patina we recognize today. By tweaking the micro atmosphere within the walls of our gas kiln, we’re able to recreate that molecular transformation, but instead of taking decades, it happens in mere hours.

The Chemistry of Transformation

During the firing process, we bring the kiln up to around 2,350°F, In order to reach that temperature we need fire. Lots and lots of fire. That fire is composed of air and gas. Or on a molecular level, oxygen and carbon. To reach this incredible temperature we need to be dialed in with the perfect ratio of the two. Too much of either and the flame becomes inefficient, stalling the kiln out and wasting precious energy. 

There is however, a brief window of time and temperature where we opt for a bit of intentional inefficiency. Creating the perfect opportunity for a bit of alchemy.

Each molecule of copper in the glaze has multiple oxygen molecules in tow. They’re stable as they are, but to be honest, they’d be perfectly fine with one less too.  Around 1800°F these oxygen molecules become temporarily vulnerable, and if given the right opportunity, will fly away with a more enticing partner. For this short window of time, we intentionally starve the kiln of added oxygen, by turning down the air supply. At the same time, we push in the damper, restricting the size of the chimney, and increasing the pressure inside of the kiln. We’ve now set the perfect conditions for a bit of molecular infidelity. Copper, who’s been holding tight to its multiple oxygen atoms, is now feeling a little loose and tipsy. Locked up in a nice toasty kiln, it starts to let its guard down.

Enter: Carbon. 

Hot. Single. Volatile. And incredibly insecure. 

Let the match making begin!

This heated high pressure environment creates the perfect conditions for the Carbon molecules to steal away oxygen molecules from the copper, transforming their molecular structure and giving the pieces the beautiful, naturally unpredictable soft pale Lichen green we so love and desire. The result? The same element, in the same glaze, can yield dramatically different colors, from deep greens to unexpected pinks.

The Beauty of Controlled Chaos

Despite our best efforts to create consistency, the reality is that each firing is an experiment in controlled chaos. Variations in the kiln’s airflow, the stacking of pieces, the thickness of the glaze, and even cooling rates all contribute to the final outcome.

Lichen glaze, for example, can emerge as a soft, pale green or a deeper, richer hue. Some pieces develop speckles from excess carbon deposits, while others surprise us with an almost Pepto pink effect—something we still don’t fully understand, but which we’ve come to embrace as part of the mystery.

And that’s the beauty of what we do. We don’t fight against the variables; we lean into them. The unpredictability isn’t a flaw—it’s a feature. Each piece, with its unique surface and subtle variations, tells the story of fire, time, and transformation, just like the Statue of Liberty standing watch over New York Harbor.

Every time we open the kiln, we are reminded that ceramics, like nature, are never static. They are in a constant state of becoming, shaped by fire, chemistry, and a little bit of chaos.

Next up: What's the difference between Porcelain and Stoneware?