Watch Casey and Jamie Davis matching colors by eye or brushing their signature Lime Wash across stucco by hand, and you’re reminded of the way painters have adorned walls for generations. The California-born brothers have continued that tradition, bringing a craftsman’s spirit to the highly pigmented, eco-friendly products they’ve been making in Los Angeles for nearly two decades.

Watch the process of making Lime Wash in action:

The seeds of what would become Portola Paints & Glazes were planted in 1998, when Casey, then a high school senior, and the boys’ father, contractor Jim Davis, drove to LAX to pick up a shipment of lime that would eventually be used to cover the exterior of a house Jim was building. The clients wanted a home that resembled an old building in the South of France, and limewash brushed directly onto raw stucco would give it instant character, while weathering over time to a soft patina.

Using lime for wall applications has a long heritage in Europe, Latin America, and elsewhere, but Jim wasn’t satisfied with the products available in the U.S., so he’d tracked down a source in Australia. The lime came as a powder and had to be mixed on-site. Longevity was not its strong suit. Says Casey: “You could paint with it, but within a few days—five max—that bucket would turn into cement.”

As Jim mastered the product’s idiosyncrasies, he talked with his sons about making a limewash for the American market. “It needed to be like paint, so you could buy it, take it home, and not open it for a week, and it would still be usable,” Casey says.

So began a nearly 10-year odyssey to develop a ready-to-use limewash, along with a dedicated primer that would enable the product to adhere both to drywall and previously painted surfaces. Jim recruited local paint manufacturer David Sibbrel to help them create a wash that merged old- and new-world techniques. While they were experimenting, Casey and Jamie honed their eye for color and began tinting paints with as many as seven organic pigments to give depth and complexity to a single shade.

In 2001, they launched Portola, named for the 18th-century Spanish explorer Gaspar de Portolá, and introduced Roman Clay plaster, which they followed with low-VOC, water-based satin and gloss enamels. But producing a uniform and long-lasting limewash eluded them, in part because of lime’s reactive nature. Finally, they hit upon a combination of ingredients and steps that produced the quality and finish they’d envisioned years before.

“Lime paint from Europe doesn’t work the same and it’s not as consistent,” says Sibbrel, who mixes lime powder into a paste that has to cure for at least two months before it can be blended into their proprietary formula. “Portola’s wash is easier for painters and lasts longer in the can.”

“Faux finishes try to replicate what limewash does naturally, but they don’t achieve the same softness or beauty.” Casey Davis

Today, Portola’s zero-VOC Lime Wash can be found on the walls of the Carmel and San Juan Capistrano missions as well as on a LEED Platinum home in Southern California. Vicky Charles, former designer for London’s SoHo House, even brought it to Europe, where local limewashes are more common, for the SoHo Farmhouse in Oxfordshire.

Though they perfected their formula eight or nine years ago, Jamie and Casey still personally test each batch and brush out color cards by hand. They admit that they could probably streamline their testing process, but for them, attention to detail is everything. “The human element is an important piece of the puzzle,” says Jamie. “We’re interested in creating a particular feeling with our products. That doesn’t really make sense in science, but for us, it’s hugely important.”

Lime Wash

From powdered lime to organic tints, the Davis brothers outline how they make their signature wall coating.