damping compound for ultrasonic cleaning board with crystal?

[coppercone2]

I have a board that has a nasty dsub connector that I want to ultrasonic clean but it also has a clock crystal on it.

Not terribly attached to that board, but I was wondering, can i stick some silly putty or something on the crystal to protect it so I can dip the connector into the cleaner for maybe 20 seconds?

I am kinda scared to ultrasonic clean the crystals.

[jpanhalt]

After an arduous search, I came across this: https://forum.digikey.com/t/ultrasonic-cleaning-of-pcb-s-with-crystals/8814

What is the frequency?

[coppercone2]

i think the crystal is 4MHz and the ultrasonic is unknown

But from a physics prospective, putting a sticky putty on the crystal should offer extra protection? Its a through hole part, but flush with the bottom of the PCB.

Should I put a little wad of putty on the bottom too?

I just wanna dip it like 2cm to get the dsub connector.