[3dem] Questions on GP2 Filter Paper

[Daniel Asarnow]

Hi Jason,
In addition to using the SubAngstrom punch to make your own #1 (or #4, etc)
blotting papers, I strongly recommend using a plastic disk behind the
paper. This eliminates the reproducibility issues caused by paper wrinkling
in the humid chamber. I use this circle cutter
<https://urldefense.com/v3/__https://www.amazon.com/Nt-Cutter-Ic-1500P-Circular-1-8/dp/B001OYA8C6__;!!Mih3wA!ACuAvx0BJrIgt0VWSbaRC5YKvdSU63W5H_Jn1dd3MU_ALiitN2Og5Ou4HjadWYm6vUi11hU9cJ7Qb3H6G4Q$ > to
cut Aclar sheets and then punch them like filter papers, but you can also
buy pre-cut Aclar "anti-contamination" disks from SubAngstrom
<https://urldefense.com/v3/__https://subangstrom.com/leica-anticontamination-membrane/__;!!Mih3wA!ACuAvx0BJrIgt0VWSbaRC5YKvdSU63W5H_Jn1dd3MU_ALiitN2Og5Ou4HjadWYm6vUi11hU9cJ7QVjPr9KU$ > (they are
infinitely reusable with periodic cleaning). I have also tried Teflon but
Aclar is stiffer and transparent. The blotting position will have to be
adjusted slightly to account for the thickness of the plastic and alternate
filter papers.

Best,
-da


On Fri, Apr 11, 2025 at 2:27 AM Jason NG (CPOS) via 3dem <
3dem at ncmir.ucsd.edu> wrote:

> Dear CryoEM community,
>
>
>
> I am writing to inquire about the choice of filter paper for GP2.
>
>
>
> We previously used Leica’s filter paper (Whatman No.1) for GP2 and
> recently changed to Ted Pella’s GP2 filter paper (47000-200, Whatman
> No.595). It has been discovered that the additional move calibration is not
> functioning properly, and the cause could be the transparency difference
> between Whatman No.1 and No.595. The system shows "liquid contact" in green
> color even when the filter paper is at the home position during the setting
> of the additional move. It would be great if you could provide feedback on
> the following questions:
>
> 1.            What GP2 filter paper are you using?
>
> 2.            If you are using Ted Pella’s filter paper, have you
> experienced the same issue as us? Does this affect the quality of your
> sample freezing?
>
> 3.            Do you have any suggestions for a GP2 filter paper trimmer
> so that we can cut filter paper by ourselves?
>
>
>
> Thank you.
>
>
>
> Best Regards,
>
> Jason NG
>
> Senior Technical Assistant
>
> LKS Cryo-EM Laboratory
>
> Centre for PanorOmic Sciences
>
> LLG03, Laboratory Block
>
> 21 Sassoon Road, Pokfulam, Hong Kong
>
> P: +852 3910-3528
>
> E: jasonng.cpos at hku.hk
>
> W: https://urldefense.com/v3/__https://cpos.hku.hk__;!!Mih3wA!ACuAvx0BJrIgt0VWSbaRC5YKvdSU63W5H_Jn1dd3MU_ALiitN2Og5Ou4HjadWYm6vUi11hU9cJ7QAHJ3lNU$ 
> <https://urldefense.com/v3/__https://cpos.hku.hk__;!!Mih3wA!H6Em6Op8kPHcHDRf21mTkF4NE8JGNjUaTV79NWCzihpbu4FXVenkOjRZ5zEVU9PuL8_GQ9Q3vz9IgXJNj-bXSv17jQ$>
>
>
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