Author: vboboe
Date: 2006-08-01 04:02
In light of recent hot debate, here's informative website regarding mpingo wood (aka grenadilla or blackwood) African Blackwood Conservation Project www.blackwoodconservation.org
Since doing some research on anything related to heat exposure and cracking, have discovered this site (among others far less comprehensive but provided useful info snippets nevertheless), and have further discovered that grenadilla is highly moisture resistant. This information calls into question both of our positions.
After this research, i'm now of the revised opinion that previous invisible fractures in the wood, not discovered in the sorting process (which discards 90% wood as unsuitable) and which survive the manufacturing process (wastage of suitable wood around 20%) -- these fractures may survive high speed shaping, drilling & cutting, but as new instruments are regularly subjected to a variety of stressors, namely:
- strong air and wind pressures ('blow out' may not be so far-fetched)
- body heat (questionable, mpingo tree grows in hotter climate than that)
- breath humidity (questionable, natural oily resistance to moisture)
- saliva (questionable, saliva digests starch not cellulose)
- sweat (questionable, oily resistance to moisture; corrosive saline, unlikely, considering grenadilla's rugged properties)
- very high frequency and rapidily changing polyphonic sound vibrations at varying dynamic levels (ah, this seems strong contender)
- cross-grain torque of fittings in frequent motion closely placed together in a rapidly vibrating conical tube (might be somewhat significant)
... well, some fractures simply can't survive * the combination * of some or all these stresses -- voila, oboe cracks up within first year.
Cracking in older oboes may include any of above, except survival rate extends over longer period of time. With older oboes also have to add more stressors, such as wood-care neglect by owner/s and abuse of the instrument by accident or carelessness.
Seasoned grenadilla is about 3-5% moist. That's very dry, actually.
Even so it is highly resistant to absorbing moisture. Grenadilla just doesn't soak up water readily like reed cane. However, if it dries out less than 3%, seems reasonable to assume this increases risk of cracking.
Question validity of popularly held hypothesis that changes in moisture cause cracking all by itself in grenadilla. Reed cane maybe true.
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