Standard block care

[Dan R]

Hello all,
I'm wondering what other labs do to keep their standard blocks clean and in tip-top shape over time. I've noticed that some of my pure metal standards are developing an oxide layer that is interfering with my standardization (especially when analyzing fresh new alloy surfaces).

We have sent one standard block back to the manufacturer to be resurfaced and cleaned, but we were not very satisfied with the results... Is re-polishing the surface typically the only way to refresh the surface? I was thinking about trying our plasma cleaner, but I wanted to see if anyone else has had experience going that route.

Also, if anyone has any good best practices for how they keep their standards when not in use, I'd like to hear about them. We keep our standards either in a dessicator or the instrument and always handle them using gloves.
Thanks for any input!
-Dan

[Probeman]

Hello all,
I'm wondering what other labs do to keep their standard blocks clean and in tip-top shape over time. I've noticed that some of my pure metal standards are developing an oxide layer that is interfering with my standardization (especially when analyzing fresh new alloy surfaces).

We have sent one standard block back to the manufacturer to be resurfaced and cleaned, but we were not very satisfied with the results... Is re-polishing the surface typically the only way to refresh the surface? I was thinking about trying our plasma cleaner, but I wanted to see if anyone else has had experience going that route.

Also, if anyone has any good best practices for how they keep their standards when not in use, I'd like to hear about them. We keep our standards either in a dessicator or the instrument and always handle them using gloves.
Thanks for any input!
-Dan

Hi Dan,
The method I've seen used to mount standards (metal mounts with set screw fixed sleeves) makes it very difficult to clean these types of mounts. If possible you should mount your own standards in an acrylic block as described here:

http://probesoftware.com/smf/index.php?topic=172.msg1436#msg1436

Then cleaning is just a few seconds of colloidial polish followed by a wipe of ethanol and oven dry, then carbon coat.  Once every 5 years or so we go back to a diamond hard lap to remove relief from repeated coloidial polishing on the soft lap.

Because this cleaning is so easy we often polish our standard mounts several times a year or more at UofO to keep them pristine.

But to answer your question, we keep them in a dessicator with fresh dessicant.
john