[3dem] Ambient humidity and glow discharger efficiency?

[Daniel Asarnow]

Hi Talya,
Recently (~1 hour) discharged grids have always worked for me, as long as I
observe the glow did take place. However I at times suspect that ambient
humidity is affecting how long my grids remain hydrophilic, as compared to
my previous lab. Could a time component explain what you're seeing?

Personally I only clean my grid blocks if there is something on them (e.g.
plastic residue after chloroform washing), or if I am sterilizing them
because the grids will be used in cell culture. Based on my observations
the mode for other users is "never"...and many people glow discharge on the
same parafilm-wrapped glass slide for years and years. Ethanol,
isopropanol, acetone, or chloroform all seem like reasonable solvents to
me, depending what might be on the block.

I also doubt if a long 20 mA glow is expected to destroy a quantifoil film.
I usually do 15 mA for 45 seconds and observe no significant damage even if
the grids are processed multiple times. But I haven't tried to go all out...

Best,
-da

On Tue, Oct 7, 2025 at 8:45 AM Talya Levitz via 3dem <3dem at ncmir.ucsd.edu>
wrote:

> Hi all,
>
> We are troubleshooting an issue where our glow discharger(s) seem to be of
> variable efficiency (sometimes making carbon grids appropriately
> hydrophilic, sometimes less so, occasionally not at all). My current theory
> is that the ambient humidity of the room is affecting the efficiency of the
> glow discharge. Has anyone encountered this or looked into it more
> thoroughly, and if so, what was your fix (account for humidity in timing /
> current? move the glow discharger into a more humidity-controlled room?
> desiccate the air going back into the chamber... somehow?). Other variables
> that have been ruled out are a faulty glow discharger, location of grid in
> the metal block, and whether it is the first glow of the day / session.
>
> We regularly have >50% humidity in the room during the summer, even with
> the dehumidifier running at full speed, because of air flow etc. variables
> in the room that we cannot change. We have two glow dischargers, a Pelco
> Easiglo and a Quorum/EMS GloQube, and have seen this with both dischargers,
> although we use the GloQube more so we have seen it more with that. At one
> point I tried to blow all the carbon off a grid with a very prolonged (5
> min @ 20 mA) glow discharge on the GloQube, and all the carbon was still
> entirely intact, which made me a bit nervous.
>
> Relatedly, how often and how do you all clean your metal blocks that grids
> glow discharge on? We were thinking of using acetone and/or alcohol, but
> would appreciate recommendations!
>
> Talya Levitz, PhD
> Scientist I
> talya_levitz at dfci.harvard.edu
> Pronouns: they/she
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