This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment List, from Sy Zabrocki--RPT Don Mannino contributes again. He has authored a fine article in the = June '99 issue of the PTG Journal about plastic piano parts. He gets = right down to the electrons in explaining why the early plastic parts = failed. He has published charts showing results of various tests = conducted by Kawai and their ABS material. The article could be titled " = All You Really Need to Know About Plastic and More".=20 Here are a few lines for those who might not get the Journal. Without = Don's permission I'll take a chance and quote just one paragraph word = for word. Here he explains exactly why the old plastic failed.=20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D Poly-vinyl chloride (PVC) resin without any additives is a hard, brittle = material and chemically is very unstable compared to other plastics. = Most commercial uses of this plastic require the addition of materials = called plasticizers to improve their resilience and flexibility. = Unfortunately the plasticizers also are not stable, so the plasticizers = "migrate" out of the action parts. What this means is that the = plasticizers at the surface of the action part evaporate into the air, = and the materials within the part then migrate toward the surface as = they try to maintain an even distribution with the plastic. As a result = the properties of resilience and flexibility in the action part slowly = degrade until eventually the part becomes weak and brittle. -------------------------------------------------------------------------= --------------------- Another form of degradation which is evident in old plastic parts is = oxidation. It's too long to explain here but it pertains to electrons in = the plastic being attracted to another atom of molecule outside the = bond, such as oxygen in the air. The rest of the article contains charts by Kawai comparing the various = properties of ABS to wood. Very convincing.=20 The January 1979 issue of PTG Journal has an article on plastic by John = Bloch. He explains the failure of old plastic as follows: "Unfortunately = the catalyst used to make the molten plastic harden never stops working = so the elbows get harder and harder over the years until they begin to = shatter".=20 This latest explanation is more precise. Thanks to Don Mannino and Kawai = for this enlightening information on plastic and ABS.=20 Sy Zabrocki--RPT ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/d6/ad/cd/94/attachment.htm ---------------------- multipart/alternative attachment--
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