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Re: Refreshing Green Stuff

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  • Ming-Hua
    Hi, I just did some testing on some really old putty (with a skin that is thick enough not to tear when you pull it off!). Two tests. The first was 30 minutes
    Message 1 of 3 , Jun 1, 2005
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      Hi,

      I just did some testing on some really old putty (with a skin that is
      thick enough not to tear when you pull it off!). Two tests. The first
      was 30 minutes in my putty oven with a 15 Watt lamp, the second 10
      minutes. I put in both seperate pieces of blue and yellow.

      Observations:
      - the putty does indeed become very soft and sticky (like ordinary
      putty would).
      - areas that have already cured like the centre bit of a ribbon and
      the skin remain hard.
      - The soft putty makes it a lot easier to remove the skin from the
      yellow ribbon, so salvaging putty works much better.
      - both blue and yellow remain soft when warm but then go back to their
      old stiffness before heating. Warming them should get them soft again.
      - the only difference between the 30 min and 10 min exposure was that
      the putty remained softer longer after the 30 min exposure.

      I also asked Bob Finkenaur (who works as an independent advisor on
      epoxy products nowadays) and this is his reply:
      ****
      My guess is that the yellow in the sample was skinned but under the
      skin the material had become stiffer but not hardened like the surface
      skin. Heat reduces viscosity of the putty so the stiff material in
      the center and possibly even the skin became softer and useable. The
      skinned has already reacted with heat and moisture so will probably
      not react with the blue correctly in any case. OK for bulking up as
      was mentioned.
      ****

      Thanks again for trying this out. I'll copy the details and put it in
      my files to add to the FAQ.

      Bye, Ming-Hua
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