Dutch Rush, and its possible use to instrument makers.
...Dutch Rush, Scouring Rush, or Horsetail grows in many parts of the world (including Northern Italy, where the world's best violin were made in the 1700's).
...I am told that before sandpaper was invented in the early 1800's, that this rush was used as a naturally occuring fine sandpaper. (I estimate it as about #600 current sandpaper). This plant is designed to pull minerals from the soil it growns in and concentrate them in the thin, ribbed, outer skin of the plant. It's concentrated silica (sand) from the ground is the abrasive quality. Inside the plant stem is hollow.
...However, as I discovered, not only is it a fine sandpaper but it also leaves a coating on the surface of the wood. This coating is clear, takes varnish, accentuates the grain of the wood for finished beauty, mostly seals the open wood grain while still allowing good varnish bonding, and minimizes mositure (and varnish) penetration of the wood. Perhaps most significant is that it has a major impact on the acoustical properties of the wood itself!
...I would summarize this effect as narrowing the range of overtones when the wood is vibrated (tapped or struck). The lowest part of the tap response range is raised and the highest part of the tap response range is lowered. This concentrates the sound energy into a narrower band which seems to really make a positive difference.
{Please listen to Opus #24 sound recording to hear an actual sound example.}
... I dry the rush stems and then cut into about 3 1/2" lengths and then a small handful of pieces are held together and taped around the middle. This leaves sand surfaces at each end of the bundel of rush. First I use a scouring (circular) motion on the wood surface and then scrub back and forth along the direction of the wood grain. Do this a second time to get the full effect. Doing it for a third time does not make an additional effect, so twice is all that is necessary.
...The sound improvement is immediate and lasting. Each part of the insturment can be treated with dutch rush and the effect is similar on each part. I would suggest both sides of the plates (before assembly and varnishing), the bass bar, sound post, bridge, inside of the rib structure and glue liner strips... in short, all parts made of wood benefit from this treatment, includeing the black ebony wood parts!
...To test this effect for your self; take a length of uniform dimension wood strip and put a line around the middle of the length. Run one end down twice with Dutch Rush and then tap each end while loosely holding in the center of the wood strip. The difference is so major that almost anyone can hear the difference.
The instrument making world may never be the same again (or maybe we will simply be going back to a former superior "skill" level of the 1700's). I believe all wooden musical instruments can benefit from this treatment and especially all the stringed wood instruments.
(c) 2017 David Langsather Salem, Oregon USA
(Revised 11/2020)
Page V_43
..At the end of a two year "Violin Timbre" research project, I would suggest this following combination gives the best acoustical results, and seems to meet the acoustical goal of increasing the strength of the lower overtones produced by the strings and at the same time reducing the strength of the upper overtones. This is a distinguishing mark of the best Cremona period violins by Grarnarie and Stradivarius; {look for sound analysis section elsewhere to see how this effect looks like on a sound analyzer chart...}
