Which Timber for Marimba Bars #2 - (Discussions with Kevin Mayberry)
-----Original Message----- From: "Kevin Mayberry" Sent: 23/10/05 2:19:17 PM To: firstname.lastname@example.org Subject: Question on marimba woodJim,
I have been looking through your website and information and it is great. I have one question and you seem to have the most knowledge of it. I have been doing research on Hormigo wood and Honduras Rosewood. You mention that for the central American marimbas they are one in the same. I was wondering how you found this. I am not an expert on woods but I have looked at some "hormigo" and it seems to be the same.
My confusion is that there really is a wood called "hormigo" that is different than rosewood. Any insight you could give would be great.
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I'm certainly no expert on timber - I looked into things a bit when I was studying and at that time I was building some instruments as well, so I found out what I could wherever I could. I do not remember what information came from where anymore. I guess my current memory can not be certified as 100% accurate but I'll happily tell you what I think I know! ;-) The most important thing is that the mostly widely accepted "Honduras Rosewood" is in fact Dalbergia stevensonii.
This is the appropriate bit from the essay I did in my honours year which you may already have read.:
".....Honduras rosewood is the material from which marimba and xylophone bars are traditionally made. (Platymiscium dimorphandrum) The tree which the Central Americans call "Hormigo" or "Hormiguillo" comes in three varieties - black, white and red, although the red is all but extinct. The small Hormigo tree is now very difficult to come by. A native of Central America only growing high in the mountains, it was almost wiped out at the turn of the century because of its extensive use for cutlery handles. Only the female tree is used as the male is full of knot holes and doesn't split evenly.
"Las Maderas Que Cantan" is the phrase used by the Central Americans to describe the timber and the instruments built with it, literally translating as "the woods that sing." Very few timbers actually do "sing", most of these being unsuitable for marimbas and xylophones for other reasons.
Some keyboards are made from American Grandillo which does not ring quite as long as Hormigo. One timber that works well for marimba is African Padoak, though it is not hard enough for xylophones and some of the smaller bars don't have the weight to sit properly on the frame.
Fairly recently (as far as the history of the marimba is concerned) a material called Kelon was developed by the Musser company for use in marching band instruments. The pultrusion process used to manufacture kelon is described by Art Ormaniec, Chief Engineer for Musser Industries as a "gathering of the glass fibres which are then pulled through a resin bath, pressed together, and finally drawn through a steel die and heat treated."
Kelon is very durable, bright in sound quality, and produces plenty of volume. Not as suitable for a concert instrument, it lacks warmth and the punchy character that comes from the special elastic qualities of timber.
Once suitable timber is found it must be seasoned for a number of years, or dried in a kiln before an additional year or so in air. It must reach approximately 7% moisture content. "That is known as equilibrium moisture content (EMC) and is the point at which, given a specific temperature and humidity, the lumber will not absorb or desorb water." 11. Even after this process the timber continues to change throughout the rest of its life, and new instruments generally have to be returned after a few years to compensate for the variation in water mass...."
As far as I know, the timber Platymiscium dimorphandrum is not actually a rosewood at all. Perhaps it fell into this common name because it was the "red" variety of the genus.
The timber officially used as "Honduras rosewood" by commercial instrument manufacturers is actually Dalbergia stevensonii.
Hope this is of some help, although once again I'm sure there are more reliable sources than me.
answers by Jim MCCarthy - 23/10/2005
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