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<DIV><FONT size=2>List, from Sy Zabrocki--RPT</FONT></DIV>
<DIV><FONT face=Arial size=2>
<P>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". </P>
<P>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. </P>
<P>=========================
==========================
==</P>
<P>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.</P>
<P>----------------------------------------------------------------------=
------------------------</P>
<P>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.</P>
<P>The rest of the article contains charts by Kawai comparing the =
various
properties of ABS to wood. Very convincing. </P>
<P>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". </P>
<P>This latest explanation is more precise. Thanks to Don Mannino and =
Kawai for
this enlightening information on plastic and ABS. </P>
<P>Sy Zabrocki--RPT</P></FONT></DIV>
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