Its time to clean parts to go into vacuum. I tested the Branson EC ultrasonic cleaning solution on a couple of gold coated DC connector pins.  Close visual inspection shows that doesn't seem to be any damage, pitting or dulling of the surface quality from 90 minutes at 60 C with the alkaline (12.5 pH) 2-3 % solution (by volume).  Pictures are attached below of the pins, left is pre clean examples and right is post clean examples.

I've unwrapped the gold coated shields and caps and inspected them.  Photos of one of the shields (loaded in front of bath). There were some minor scratch imperfections from the original manufacture and it isn't blindingly shiny (i.e. polished) but is otherwise in a good state.  Similar to aluminum foil we probably don't want a super shiny surface for room temperature emissivity at ~10 µm. According to RaNA the dull side of Aluminum foil has a lower emissivity at 10 µm than the shiny side. He may have a reference to add.

The sonic bath has been cleaned. I've made a tray holder to suspend beakers in the main bath (pictures attached). These beakers have clean DI water and Branson EC detergent to loosen any dirt and oil.  The main sonic bath is filled with regular tap water and some general use surfactant to improve the transfer of mechanical energy.  Usually surfactant is recommended to lower surface tension. This improves cavitation in and around the parts to be cleaned. Although it may not be necessary the main bath.  I found that the standing wave pattern on the surface was much stronger once I added a bit of general purpose non-foaming surfactant. It seems to be doing a better job so this is probably the way to go.

The shields were suspend from thin wire, small pins for crimping and connecting are just directly in the small beakers.  I was unable to fit the end caps into this cycle so they will have to be done tomorrow.

The shields were put in for 90 minutes at 60 C with ~ 3% solution of Branson EC surfactant.  Once the time is up I will pull them out, wash them down thoroughly with deionized water and then with isopropanol/methanol.  They'll be left in the flow bench overnight to air dry and I'll put them in for a bake cycle tomorrow.