old "elbow" plastic

[Don]

Hi Joe,

It's quite simple really. The speed of any chemical reaction doubles with
every 10 degree C. increase in temperature. Most plastics are made with
polymerization process to make long chain molecules. The long chains
eventually break down and you end up with very brittle parts. Heat from any
source will speed the process of depolymerization.

At 10:04 AM 10/23/02 -0700, you wrote:
>I was told many years ago, (I forget by whom), that the possibility of
>electrical ions, emitted by the D-Chaser, effected that type of plastic.
>Okay, it's a stretch, but on every piano, with plastic parts, of that age,
>and with a D-Chaser, (improperly installed, IMA), this was my observance.
>The reality is that the catalyst that hardened the plastic, (in the mold),
>continues to harden forever. IMHO, it is just a matter of time before ALL of
>the plastic parts, (of that specific era), will fail. The REAL FUN ones are
>those with wippen flanges, butt flanges, damper levers/flanges, backchecks
>AND Jacks, made of plastic!
>Replacing the flanges is not really a big deal, compared to replacing the
>whole damper lever, sans head/felt. Alignment is always difficult.
>These things seem to run in spurts. In the seventies I did a whole wad of
>them. Then, I didn't have any to do until mid 80's. Then there was a long
>period where I thought, "Well, I guess they've either been given last rites
>or have been taken care of." WRONG! In the late 90's another wad of
>them....."same thought".....WRONG AGAIN<G>!!!! .....2000 rolls around
>another wad of them, ( I did 4 in two months!).....Gawd, Now they're rearing
>their ugly head AGAIN!
>How many million of those beasts were made???????? I think they're breeding
>while they are being left to their own devices!!!![G]
>Best Regards,
>Joe Garrett, RPT, (Oregon)
>
>Been There, Didn't Like It, So I'm Here To Stay! [G}
>
>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives
>
>

Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T. Tuner for the Center of
the Arts

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