Thanks for the compliment on my site. I've tried to fill the gap in terms of quality information and illustration.
I just use any old dish washing liquid. And a soft rag or sponge to rub it on and off. I rub with the grooves (helps move out any grime stuck in the tonal grooves) and I rinse well with just water at the end. Nothing fancy.
If you like the mellower sound, don't clean them much because you may find they get brighter and less mellow. I'm agnostic when it comes to what cleaning (or the more extreme polishing) does to the sound. I'm still waiting for good before after sound files which we can use to test out the theory by blind listening tests. But I know a number of people believe cleaning makes a strong difference. I suspect (while waiting for some evidence) simple cleaning it might do a tiny bit to the sound in most cases. But opinions vary and are strongly held.
Welcome I second that mid 60's last of the hand hammered
What I'm seeing on those hats looks like the familiar concentric ring hammering style. I believe it is done with force provided by a machine, but perhaps targeted by a person guiding the cymbal freehand. But I don't really know. I've been trying to develop a vocabulary for describing these matters:
http://black.net.nz/avedis/hammering.html
which is still very much under revision. And I generally try and stick to describing the pattern we see rather than inferring whether the force was supplied by a human arm or a mechanical amplification.
While there may be some hand hammering on some mid 60s cymbals I don't believe it is that frequent. And if it is present it doesn't seem to account for the bulk of the hammering done for shaping the curvature of the bow. If we are lucky Drumaholic might provide us with some more up to date comments, but my understanding is that speaking generally he used to believe that Trans Stamps were the last of the hand crafted ones.
http://www.drumforum.org/index.php?/topic/8515-18-type-i-transitional-stamp/?p=107278
