Thomas

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I (Personally) have never heard anyone mention or use the term “Outgassing” with regards to the grease used on SCTs. In my (Personal) experience, and I have had a considerable amount of machining, building, and TIG welding high vacuum systems together for Arizona State University not to mention working on dozens of Electron Microscopes daily for 20 years, this is the only place where the vacuum is remotely high enough to cause things to outgas. We had to be painfully aware of what was put into the systems even to the point of what metals were used in the construction of these instruments.

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We of course wore gloves and triple washed everything with TCE then Freon, lab grade purity of course. We then housed the entire microscope then baked it out for 24 hours at about 4000° f. Even a fingerprint would “outgas” and would be visible on the Mass Spectrometer we used to monitor this situation when we pumped the system down to 10 to the negative 12 torr.

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But this is the first time I have heard of “outgassing” with reference to a SCT mirror so (In my personal opinion) outgassing is not a concern.

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What can be of concern is having grease with an low “Dropping point” melt and drip all over the inside of your OTA. I have had that happen and had the grease drop onto my corrector lens. If your scope is left outside in the Arizona Sun this can be a concern but I think outgassing is not even remotely possible under normal operating conditions, emphasis on “Normal”. Now if you are are operating your scope in space or a vacuum chamber you might run into problems.

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The above is based on my experience but is not the last word.

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Gary

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Carpe Noctem

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Sent from the Astro Cave via my MS Surface Tablet

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