On Wed, 12 Jul 1995, Barrie Heaton wrote: > It seems most of you seem to prefer using wood alcohol to > recentre your flanges. I am fascinated I am assuming that you > only use alcohol on relatively new bushings as the old bushings > before 1950 would have been glued in with animal glue. The > solvent for animal glue is spirits. So I would imagine the same > problem arising with the centre pin lubricant ie., bushings > falling out. > > Does the alcohol not effect the glue in new flanges as I am led > to believe that a crossed linked pva glue is used and pva is > water soluble over a period of time. So in using alcohol on > centre pines are you not creating problems for the technician in > the future. A colleague in Scotland tells me that a major > American manufacturer recommends alcohol on its centres is this > true? if so is it a ploy by the manufacturers to shorten the > life of the piano therefore increasing sales. Or is it just that > I've got hold of the wrong end of the centre pin. Barry, The major American piano manufacturer that I work for has two methods for treating tight action centers. 1) a 1:8 silicone/naptha solution: 1/2 pint silicone to 1/2 gal. naptha apply liberally to all action centers 2) methanol/water shrinking solution: 75% water 25% methanol, to be applied to those centers that didn't respond to the first treatment. Drying time is 4-6 hrs., using a hair-dryer speeds it up. I have used both techniques, with some success, on new instruments. The silicone/naptha treatment is by far the more effective, but messier (DON'T spill any on a new finish!) Silicone also does strange things to lacquer, and if you have silicone in an area where you spray (or even do touch ups) it causes fish-eyes and running. On older instruments, both treatments are less effective, and repinning or re-bushing is the best long-term repair. I have not had any trouble with glue loosening the bushing after these treatments, but I haven't pulled and checked every center, either. These techniques are for quick repair, not as long-term solutions. (Any chance that alcohol is a single malt?) (-8 Rob Kiddell C.A.P.T. Edmonton, Alberta Canada
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