Author: Dale Phillips

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Questions: French Polish VS Olive Oil

Questions: French Polish VS Olive Oil

by Gary Southwell and Koen Padding

Originally published in American Lutherie #97, 2009



Stuart Mewburn from London, England asks:

A recent request for an instrument finished with olive oil prompted me to do an experiment. I took two pieces of European spruce, the same size, oil finished one and French polished the other. I used virgin olive oil, applying one layer a day with a cloth and finished the next morning with Micro-mesh. Over fifteen days it built up a lustrous finish. Over the same time I applied thirty layers of French polish to the second piece of spruce. The oiled spruce (fifteen layers) weighed 2g more than the bare wood. The French polished spruce (thirty layers) weighed 1g more than the bare wood. If these figures are multiplied up to the size of the lower bout it means that the oiled top adds 33.2g to the weight of the working part of the top and the French polish adds 16.2g. When you consider that a bridge weighs about 19g–20g that’s a significant increase in weight for the strings to drive.

The experiment begs a couple of questions. Has anyone done similar tests for other guitar finishes? To what extent does the mass of the finish affect the tone of the instrument? And as an aside, how well will a finish like olive oil hold up?

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Questions: Stringed Instruments of the Middle Ages

Questions: Stringed Instruments of the Middle Ages

by Wes Brandt

Originally published in American Lutherie #85, 2006

 

Fabio Ragghianti of Pietrasanta, Italy asks:

I’m looking for plans for stringed instruments of the Middle Ages: citara (kithara), fidula, and such.


Wes Brandt of Amsterdam, Holland responds:

No known examples of necked European stringed instruments survive from before about 1500, so they are known mainly through iconography and the written word. We can only surmise the thicknesses and internal structure. Also, seriously consider the type of stringing and string tension as you develop your own plan. The Early Music Shop in England (www.e-m-s.com/cat/stringinstruments/stringed.htm) has kits that may provide starting points for sizes and dimensions but are not to be taken as “historically correct.” A good site for photos and iconography is www.instrumentsmedievaux.org. Spend time on the Internet looking for references to books, journals, articles, essays, and iconography, then use interlibrary loans. Look for string makers such as NRI (www.nrinstruments.demon.co.uk/Guide.html), also early music societies, players, and other makers; and of course plans (``drawings’’ in England). Try searching in other languages as well; obviously you must learn the translated name of the instrument. ◆

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Accelerator for Superglue and More

Accelerator for Superglue and More

by Chris Pile

Originally published in American Lutherie #10, 1987 and Big Red Book of American Lutherie Volume One, 2000



I would like to inform fellow members of recent developments in the cyanoacrylate area of my repair business.

The makers of Jet have added two new products to their line which have quickly become indispensable in the completion of my daily work. The old, reliable Jet and Super-Jet have been joined by Slo-Jet and Jet-Set.

If you remember, Jet is the familiar thin, quick-setting superglue, and Super-Jet is thicker and slower to dry. Slo-Jet is even thicker and much slower to dry, consequently filling gaps and holes even better than was previously possible. As a matter of fact, it dries so slowly I’ve no idea how long it would take to cure if I wasn’t using the other new product — Jet-Set.

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 This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

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Questions: Measuring Guitar Efficiency

Questions: Measuring Guitar Efficiency

by Alan Carruth

Originally published in American Lutherie #73, 2003 and Big Red Book of American Lutherie Volume Seven, 2015

 

Buck Montoya of Wichita, Kansas asks:

I’ve heard and read that acoustic guitars are horribly inefficient (less than 10% if I remember correctly). Is there a method of measuring a guitar’s efficiency that could be performed by the average luthier without the resources of a fully equipped lab?


Al Carruth of Newport, New Hampshire responds:

I think most instruments are pretty inefficient. Neville Fletcher and Tom Rossing discuss this in their book, The Physics of Musical Instruments. The figure that I’ve been given for the violin is about 2%, and Ervin Somogyi said at the GAL convention in ’92 that guitars run around 5% efficient.

It’s not easy to measure the efficiency of a guitar. For one thing there is so little power involved: any source of noise will throw the measurement off. For another thing, guitars are complex sources: even the headstock radiates some sound. You have to take measurements all around at all different frequencies and add them up to find the total. And you can’t take the measurements from close up, since the phase cancellation of the different radiating areas can skew the results. The cheapest calibrated microphone and preamp combination I know of costs several hundred dollars, and it’s probably the wrong kind of mike for this. I wish it were an easy measurement to make: I’d love to know how efficient my instruments are. But try as I might I can’t think of an easy way to do it.