By James N. McKean

When I was a violin-making student at a school in Salt Lake City, I had a cat. Even as a kitten, she seemed to want to spend all her time in my shop—which was then just a bench in the back mudroom, wedged between the stairs to the basement and the coats hanging on the wall. Thus her name: Shopcat.

Shopcat was unique, at least in my experience: Her coat seemed to reflect blues and greens, with streaks of yellow. Her eyes were huge, and the deepest emerald—they would glow in the changing light as she lay on the bench, watching me work. That glow is common to all cats—in fact, there’s a name for it: chatoyance. It means to shine from within, with a spectrum of colors that changes with the light. Usually it’s used to describe precious stones, like rubies or emeralds, but it’s also the perfect word to describe a fine varnish.

The greatest of all violin varnishes are found on instruments from the golden period of violin making. You see it on the very first violins that came from Andrea Amati. It was in wide use for the next 200 years, disappearing only toward the end of the 18th century. And while it’s often called Italian varnish, you can find it on instruments from all across Europe, particularly from the Netherlands.

The stunning beauty of the varnish is what most people notice. It’s a bit misleading to talk of it as “the” varnish; it varies widely in appearance and consistency, ranging from soft to chippy, from light yellow to the deepest wine-red.  It can appear transparent, but it has body to it—and yet, no matter how thick, the wood underneath shines through. Even after centuries, it looks almost as though the wood is lit from within. That’s the chatoyance.

“The perfect violin varnish has to protect the wood but be acoustically transparent. Needless to say, it’s not quite that simple.”

The finest varnishes also create an effect known as dichroism. As you tilt the violin back and forth, the flames will go from gold to dark red. The wood is saturated with color, and yet it doesn’t look stained. This is often ascribed to the magical Italian ground, the Holy Grail for untold generations of violin makers. As for the varnish itself, these days, after centuries of hard use, it’s rare to find an instrument that has a lot of it left—one characteristic that’s universal is that it is very fragile, and wears easily.

I once talked to a professional varnish maker about what violin makers were looking for. He just shook his head in disbelief. “Everything you’re saying is exactly what varnish is not supposed to be,” he said. And he was right. Whether it’s a desk, a table, chairs, the wood trim on a boat, or even the floor—you want to be sure that what you put on it will stand up to anything.

Modern varnish is a marvel of engineering—immensely strong and durable. It achieves this through polymerization. The individual molecules bond together through crosslinking, creating a seamless, impenetrable surface. But that’s the worst thing you can put on a violin. Why? Because a violin is designed and built to maximize vibration, and the tougher the varnish, the more it dampens the vibration.

So the perfect violin varnish has to protect the wood but be acoustically transparent. Needless to say, it’s not quite that simple. Think of a tree. Just as a violin is basically no more than an amplifier, a tree is essentially a hydraulic system. The cells are designed to transport water from the roots up to the crown—often well over a hundred feet. That hydraulic system doesn’t stop when the tree is cut and the wood harvested, dried, and then made into a violin.

When you start varnishing, you’re not putting it on the violin, but into it. Whether it’s a separate ground or the varnish itself, the first few coats are like water poured into desert sands. What we see as varnish is actually like a thin layer of ice on a deep lake. That’s why it doesn’t matter quite so much that the varnish is so fragile. The purpose of varnish is to protect the wood—and what builds up in it is as important for that as the little bit on the surface. When it wears away it’s easy to replace it with a thin barrier varnish.

The essential truth is that the best varnish acoustically is the worst structurally; one of my friends quite aptly described the Italian varnish as a “magnificent failure.” And since you don’t tend to find that kind of thing commercially available, the problem for any violin maker is re-creating it.

And that’s a real problem, because in order to re-create something, it’s helpful to know what it’s made of. There has been plenty of scientific analysis of the classic Italian varnishes and ground. It isn’t that we don’t have the data—we have too much of it. Gas chromatography shows everything from gold to uranium and all kinds of organic compounds. This isn’t surprising; the materials used were far from pure. And the procedures were not exact, by modern standards.

There are many recipes for varnish in the historical record, going back to the Renaissance, when Andrea Amati was varnishing his instruments. But most of them are very simple—maddeningly so. Some oil, some rosin, cooked together. But you can get almost anything under the sun by doing that. It seems too easy—but that, again, is deceptive. Those might be the basic ingredients, but now, after 40 years of research and experimenting, my varnish takes four separate steps and weeks to make. The ingredients come from as far afield as Russia, the Baltic, Holland, and Italy. They are quite expensive—a thousand dollars in supplies yields at most a gallon of varnish.

It’s also quite dangerous.

As one scientist put it, cooking down the resin can result in a “self-sustaining exothermic reaction.” Or, in plain English, it can blow sky high. And, on rare occasion, it has. If you want to make your own violin varnish, the best place to start is online—at fire safety sites.

When I’m making it, or varnishing an instrument, or looking at the way the wood shines and glows under the light, and how the color of the wood shifts as I tilt it back and forth, I sometimes think of Shopcat watching me work. She had that slightly amused expression that cats have when they’re watching silly humans try to do serious things. I was focused on the tools and the wood, but the secret was right there in her eyes all along, glowing from within, shifting color with the changing light. Always the same, ever-changing: a mystery worth a lifetime’s exploration.