Borates and Stradivari: A Sound Science

:: Monday, October 25, 2021

For centuries, musicians have revered Stradivarius violins for their superior sound quality. Countless researchers over many decades have attempted to discover the secret of their tonal brilliance—generally forming inconclusive results.

Now, new published research has confirmed previous theories that the chemical treatment applied to the wood—not the wood itself—is largely responsible for Stradivarius instruments’ unique sound quality. Boron plays an important role in protecting wood from pests, fire, moisture, and decay fungi. For centuries, craftspeople have used borates for wood protection.

The latest Stradivarius study analyzed maple and spruce wood samples used to make soundboards for the instruments. The study identified trace amounts of five key chemicals, including borax, used in the preparation of the wood.

This new analysis shows that this protective treatment may also influence acoustic tuning—giving the instruments their incomparable sound.

Borates and Stradivari: Creating the Holy Grail of violins

Regarded by many as the greatest violin maker in history, Antonio Stradivari crafted his instruments from his shop in Cremona, Italy, perfecting his instruments’ proportions in the early 1700s. His special approach set a precedent for unparalleled sound quality.

Today, only about 650 of Stradivari’s violins remain in the world, and a single instrument can be worth millions of dollars.

The sound Stradivari’s instruments produced were so unique, so special, that people questioned how it was possible that the crafting alone was responsible. Was it the type of wood? Was it because it came from a specific tree, subject to particular growing conditions? More recently, pundits have asked whether the perceived quality is all in our heads—a psychological tease given merit by Stradivari’s name and reputation.

In 2006, a Texas A&M biochemistry professor and violin maker, Joseph Nagyvary, proposed the theory that treatments applied to preserve and protect the wood were responsible for the exceptional acoustics.

Nagyvary had noticed wood artifacts from the same era frequently show significant damage from wood-boring insects. Yet, wooden objects from the Italian cities of Cremona and Venice exhibit little or no damage. The most pristine of the surviving instruments are usually finished with a brittle, almost glassy substance.

He deduced that someone had discovered a way to chemically treat the wood to protect it—and proceeded to recreate the effect by experimenting with various types of preservatives.

As a chemist, Nagyvary knew the power of boron had been harnessed for its unique chemical and physical properties long before the 18th century. Boron was used as a biocide even in Stradivari’s time.

Nagyvary also knew borates act as a cross-linking agent, binding different molecules together in a gelatinous web and filling tiny pores in the wood. He added a varnish that included borax to Italian maple and observed that the application made the wood much harder and stronger. It also had a profound effect on the acoustic properties of the resulting violins.

After Nagyvary’s initial efforts, the theory gained steam. In 2016, researchers at the Swiss Federal Laboratories for Materials Science and Technology studied the effects of varnish on the wood and resulting sound quality.

They discovered varnishes increase wood’s dampening—its ability to absorb and stop vibrations. This unique ability has a profound effect on music.

Can you hear the difference?

Many people believe Stradivarius violins mimic or imitate the resonance frequencies of female singer’s voices. Their iconic sound makes them widely recognizable. But can you spot the difference?

Take a listen to a few different violins to see if you can pick out the Stradivarius:

Beyond Stradivarius: Borates preserve and protects wood

Applying a borate-infused treatment to wood prevents it from biodeterioration. For pests, borate biocides are lethal, and they prevent fungi from damaging wood by attacking them on a cellular level, disabling their ability to digest wood.

Because of its superior protection and environmentally safe properties, borates are essential to modern applications such as the wood used in home construction. Using borates in wood products can preserve and extend their life, supporting sustainability efforts.

U.S. Borax is committed to preserving and adding value for future generations. We’re proud that boron may play a role in helping musicians delight classical music fans.


U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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