GSI Helmholtzzentrum für Schwerionenforschung
Dear Chamberbuilders, after I had some doubts on the quality of the new hardener, Jörg did some more tests and we concluded that as far as we can tell the quality is OK. Jörg will send a mail with more detail himself. I would however like to make you aware of some (slightly) changed behaviour of the glue with the new hardener. 1. Surfaces are more likely to stay sticky. This is dependent on the humidity level, but sticky surfaces already occur below 40% RH. This does however not influence surface conductivity to an extent that would be dangerous to us. 2. It seems to me that with the new hardener it takes somewhat longer for the glue to fully cure. It seems that a curing time of 24 hours for the AW116 is enough according to GSI experience. Previously we had the feeling that the AW116 was cured already after ~12 hours, which definitly is not the case anymore. This has some implications on the chamber building procedure: When gluing the frame and radiator, so far we only waited until the next morning before we removed the frame from the gluing table. Now we should wait another day. This is necessary, because otherwise the glue still is flexible and any bending of the L-profiles will stay more or less unchanged. (A certain amount of bending will always be present due to mechanical tolerances). This was verified in tests at Heidelberg so please do it. best regards, Clemens