tube damper help

I have no idea how hot a well-driven power tube can get. That's why I suggested the Kalrez. That'll take anything, short of a meltdown. For preamps, most anything should do.
The reason I specifically do NOT like Silicon is that they are made with a liquid binder which under some (admittedly VERY unusual) conditions can 'weep' out.
This binder is silicon OIL which will really mess something up. Without getting real toxic, I don't know how I'd remove it. I don't think soap and water will touch it.
TVAD, Do you mean f or c temp scale? Silicon is generally considered good to about 450f = 230c. That is about as hot as your home oven can get and not really all that hot. We used silicon on equipment flanges which were water cooled. This means temp no higher than in the 90s c. The equipment itself ran at 600c = 1110f and was used in semiconductor processing.

I think you tube guys are right. I don't see how a tube could run THAT hot!
If I ran tubes and was seriously interesting in damping microphonics, I'd use 2 different rings per tube.

I have used herbies and the stock dampers that come with audio research pre amps and both seem to work well;I asked Ralph from atmasphere what he prefers once in a thread and his reply was to stay away from tubes that are known to be microphonic if you can;good advice I thought.

I don't know specifically which compounding we used at work.
Here, however is a link to a site which shows 2 different silicon compounds with way different max temps listed.
I would say the higher temp one is to be preferred. At least for output tubes.

http://www.marcorubber.com/silicone.htm

My experience with o-rings tells me I would tend to avoid the silicon. While I doubt in home use you'd ever get one to weep, there is a binder oil as part of the compound. We used to put them in an oven at over 100c+ at very low pressure. They would weep out oil. We couldn't use them as sold to us for reasons completely unrelated to tube guys use as a damper. Later, we found a source for pre-baked rings and began using them.

My o-rings are the S1000 compound from Marco Rubber and they neither weep nor jump for joy.

:-)

David