Building a Better Guitar Pick

A few years ago I fabricated several stainless steel guitar picks in my company’s machine shop. As a long-time guitarist, I loved the flex-free feel of the stainless pick, which limited response time during fast picking runs. But ultimately, the metal-on-metal contact of the hard pick wore down the strings and led to string breakage after only a few days of playing.

As a thin film physicist with decades of experience at NASA and in the private sector, I’m well aware of the benefits of very hard, very low friction coatings for wear applications. I was curious how such coatings could help my picks.

My company, GENVAC Aerospace, Inc., specializes in chemical vapor deposited diamondlike carbon (DLC) coatings. Over the last 20 years the company has developed high-frequency (millimeter wave and terahertz) amplifiers. We have made extremely robust DLC-coated infrared lenses for military aircraft for more than 15 years.

Our technical team, which had no previous experience working on metal coatings, began to modify the DLC deposition process to enable a robust coating on metal parts. We hoped to take advantage of numerous wear-resistant coating opportunities in the tool and metal fabrication industries.

I realized that optimizing a DLC coating for a stainless steel guitar pick would teach the GENVAC team how to deposit the coating on metals. The hardness and very low coefficient of friction attributes of diamondlike carbon could also potentially result in a revolutionary guitar pick by significantly reducing drag, enhancing playability, and eliminating the string breakage problem.

It took several months of iterating through deposition parameters in our 11,000-square-foot facility on the eastern edge of Cleveland, Ohio, but eventually our DLC no longer chipped off the edges of stainless steel guitar picks and other three-dimensional steel parts we tested. By early 2015 GENVAC had optimized DLC coatings for metals using two processes: plasma-enhanced chemical vapor deposition and direct ion-beam deposition. The coating properties were modified such that the coating no longer delaminated from the metal surface and conformed somewhat to flexing and ductile deformation. That was accomplished by reducing stress in the DLC coating and modifying the properties of the proprietary adhesion layer.

During this development period the company also developed metal finishing processes which provide an adequately smooth edge on hardened steel cutouts in mass quantities without hand working. This process chain, coupled with DLC optimized for wear resistance on metal substrates, led to a new product line at GENVAC: ROCK HARD Diamond-Like Carbon Coated Guitar Picks.

Although they’re “just” guitar picks, they are significant because they actually enable faster picking with less effort (something my fellow guitar enthusiasts will certainly appreciate ) due to the very smooth low-friction “no-drag” surface resulting from the hard DLC coating. Atomic force microscopy measurements made at Case Western Reserve University show that the thin DLC coating reduces the surface roughness of the electropolished stainless surface by a factor of 2. Also, the coefficient of friction is reduced more than a hundredfold, from about 0.78 for stainless steel on steel to less than 0.005 for DLC-coated stainless steel on steel.

Ultimately GENVAC intends to optimize DLC coatings for all metal wear points on the guitar, including the bridge, saddle, nut, tuners, and even possibly the frets. The elimination of wear and reduction in friction at these points will significantly reduce if not eliminate detuning and string breakage and likely result in a unique sound. Many other musical instruments can benefit from DLC as well.