By Steven Wasser - President, Verne Q. Powell Flutes, Inc.
Flutes have come a long way in the last 100 years, yet many musicians prize old Louis Lot, Haynes, and Powell flutes. Flute scales are better today, precision machining produces superior parts, synthetic pads are more stable, and silver is silver – or is it? Does something happen to silver over time that could have a beneficial effect on sound? In fact silver does change over time. It stress relieves and age hardens.
|Steven Wasser giving tour of Powell production facility|
When any metal is worked, such as by cutting, extruding, or bending, it becomes stressed. In its “relaxed” or unstressed state, the molecular structure of metal looks something like graph paper, with a nice, regular geometric structure. When the metal is stressed, some of those boxes get scrunched up, and some become bigger and misshaped. As a result of these irregularities the metal is unable to vibrate as freely as it would do in its pure, unstressed condition. These irregularities can cause dead spots in a flute. In our experience resonance is better with silver that has been stress relieved.
Hardness correlates with stiffness or rigidity. When metal flexes it absorbs or diffuses energy. Since flutes are very inefficient at converting your air into sound, small differences in how that air energy behaves can affect acoustical output. We believe that the slight age hardening of older silver flutes has a positive effect on response.
Does anything else change over time with older silver flutes? Well, yes, the instrument is subject to daily vibration from being played and is swabbed. We cannot document what effect, if any, might arise from these activities, but some flutists are convinced that they make a difference.
Is there a way to produce some of the effects of aging on silver in new silver flutes? Yes. At Powell we use a variety of techniques to keep the molecules of the flute body as even as possible. When we solder we generally heat the entire body at once, evenly, rather than spot soldering one location at a time. And when we’re done, we cryogenically treat the entire flute. There is solid documentation that cryogenic treatment age hardens and/or stress relieves certain metals, but data for the effect of cryogenic treatment on sterling silver are inconclusive. Based on years of subjective testing we believe cryogenic treatment stress relieves silver and slightly age hardens it.
Some of the qualities of older flutes may also be perceptual rather than real. A number of years ago one of our customers was complaining that new Powell flutes did not have cups properly centered over the tone holes. I was surprised because we use gages that are accurate to within the thickness of a human hair. Then this customer came with Powell flute #2000 made by “Mr. Powell” which he proudly showed me. As I looked at this flute I noticed that the trill cups were severely bent – nearly 1/8”. Apparently when Mr. Powell made this flute the trill cups were not centered properly. Rather than re-make the keys he simply bent them so that they covered the tone holes. When I pointed this out to the customer he was shocked. He somehow noticed if our new flutes cups were off center by 0.003”, but never noticed that the trill cups on Powell #2000 were grossly off center.
Beauty is in the eye of the beholder. We have thought about the way flutes age and have tried to mate a process for aging the flute with modern elements like improved scale and keys.