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shelf-life concerns

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  • Gerald Lange
    Apologies. I didn t mean to be an alarmist with that last post on shelf-life. Knowing that raw stock has a limited shelf-life is useful information in itself.
    Message 1 of 1 , Sep 22, 2001
      Apologies. I didn't mean to be an alarmist with that last post on
      shelf-life.

      Knowing that raw stock has a limited shelf-life is useful information
      in itself. Knowing exactly when it will go bad is another thing
      altogether.

      A technical rep at Handschy recently told me that ink has a shelf-life
      of one year. This goes against the old wisdom that the older an ink is
      the better it gets. I wouldn't have believed him until I discovered
      that some of the newer formulated inks seem to go bad from the inside
      out, not from the top of the can downward but from the bottom up. This
      completely ruined a job because the ink was notoriously stiff in the
      first place and we weren't attentive to the fact that the abnormal
      stiffness at the bottom third of the can was due to loss of carrier.

      Same with rollers. A friend recently gave me a durometer for measuring
      the hardness of printing rollers. Now I know that my rollers are
      increasing in hardness almost a point every one and half to two
      months. How useful is this to know? My roller rep says that when they
      hit Shore A 50° they will fail to split the ink altogether.

      So do I throw the rollers out when they hit Shore A 49°? Do I throw
      the ink or the raw photopolymer plates out when they hit the 364 day
      mark?

      No, I'll most likely use the rollers, the ink, and the plates until
      problems BEGIN to occur that can't be blamed on other factors. Armed
      with a bit of knowledge about materials degradation, however, when
      certain problems do start occurring, I will at least have some clue as
      to what the cause may be.

      Gerald
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