[3dem] Ambient humidity and glow discharger efficiency?

[Talya Levitz]

 Thanks, Daniel.

In our case we can see that the hydrophilicity is an issue immediately,
although it will decrease over time. We start to see issues in grid quality
after 10-30 minutes of sitting out in the air post-discharge, which is
faster than I have seen in other labs. I wonder if whatever is causing the
decrease in overall hydrophilicity is also contributing to the length of
time the glow discharge can last.

It definitely can't hurt to clean our block and discharger. We don't do
anything with it except glow discharge unmodified grids, but people touch
it with their bare fingers, so I'm sure there is grease on everything from
that.

Good to know regarding the destroying the film. Another easiglo we
occasionally use destroyed the film at much lower time than 5 minutes at 20
mA, but it tends to randomly destroy carbon films anyways, likely because
it is very dirty.

I have gotten a good number of offline responses — will send a summary out
for folks in a couple days!

*Talya Levitz, PhD*
Scientist I
talya_levitz at dfci.harvard.edu
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On Tue, Oct 7, 2025 at 7:50 PM Daniel Asarnow <dasarnow at gmail.com> wrote:

> 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
>> _______________________________________________
>> 3dem mailing list
>> 3dem at ncmir.ucsd.edu
>> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem 
>>
>
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