Author: L. Omar Henderson
Date: 2001-09-24 13:32
Dear Folks,
I have been bombarded with EMails with specific questions so I thought that I would share some common threads in these questions and my responses.
Generally in older clarinets I see pores or channels that are clogged by either of two proccesses. The first is the use of some polymerized agent (varnish, linseed oil, tung oil, etc.) or partially polymerized oils of various types and some matrix forming agent (either dust, dirt, case cloth fuzz, swab fuzz, etc.. The second is just dirt or biolgical detritis, fuzz, with a smaller amount of internal oil or added oil forming a plug.
Someone asked what furniture refinishing history had to do with this whole story and it is primarily the removal of old finishes without harming the wood and removing too much of the natural oils from the wood in the process. (I dont't know how many of you have had furniture finsishes removed by the commercial hot dip process but what you get back is a cleaned, dry piece of lifeless balsa wood). Fine antiques require extraordinary measures, treatments, and formulations. Early on I developed organic solvent mixtures that would soften and remove most of the type 1 clogs (this was not a commercial endeavor but one to learn about the process and analyzed the types of oils used on the orginial instrument for use in compatibility studies with my own oil mixtures) The second type of pore clog can be pretty well removed by a mixture of chemical detergents in a water solution. Both of the processes are not DIYS and attempts can cause more harm than good to the wood. I will not provide formulation information because it is too dangerous in a household situtation to use organic solvents and in the second case it requires experience to properly use the detergents.
The other questions dealt with whether the above processes were necessary on older instruments. Only your repair person should answer that question. I do not want a union card myself and leave those decisions to the most qualified people. I have performed these services for clients in the business but only as a favor and not a paid service job.
Is pressure oil treating better than soaking, better than surface application. Yes, maybe, possibly. Again without the proper setup, equipment, materials and knowledge, --- pressure treatment is not a DIYS project. As I referred to in an earlier post - parameters of time, temperature, pressure, and oil have to be carefully controlled in the process. Simply using more pressure may be more harmful than useful in the process - what works for pine does not work for grenadilla wood!
Soaking at controlled room termperatures for some period of time is probably better than surface application of oil alone. Again, one must know that the oil used is compatible with the types of oil used in the original manufacture, that pores have been opened to the extent possible, and that the oil used will not itself cause problems later in life of the instrument or change the resonant qualities significantly.
Suface treatment - I do both outside and inside myself - will replentish the oil balance of the wood and also aid in the distribution of moisture throughout the wood. Why do cracks ususally form on the surface? - I've seen a lot of both kinds - internal and external - but one could speculate that the moisture distribution was greatest on the internal surfaces while the surface had less water content and this causes external cracks. Cracks are a complicated phenomenon and simple explanations probably are not satisfactory to explain the complex series of events leading to the "crackquake".
The Doctor
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The Clarinet BBoard
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