Oi, the Netherlands are so poor? Such things we had to do in eastern Germany over 20 years ago. The result was always much worse than in commercial grids. Now the result in modern TEM's with FEG is much insufficient (contamination). Time is money.

If I nowadays would do it again - Finally, I would use a plasma cleaner!?

Dear Duco, and also hello, dear Volker,

I will not comment on or countries...(;-))

As an EM-Lab in a governmental (now practically privatized) Central Hospital in Salzburg we are / were poor too...(EM-Lab expected to be closed next year after 33 years of operation). Cleaning of "old, used / unused grids - I guess - was done everywhere in the EM-Labs (not only in former Eastern Germany).

We always have used "old" grids (usually formvar mounted) after a cleaning process, at least all those grids we couldn't use for any reason (e. g. holes in formvar film or crude particle conatmination etc., as seen by inspection prior to collecting sections, bent grids). So the grids normally did not carry any section(s) and also weren't inserted into the TEM and/or contaminated by the beam. The cleaning procedure (which nevertheless should be possible also for used grids WITH adhering sections) always consisted of thorough dissolution first in the organic diluent the formvar was dissolved (e.g. chloroform 100% pA, 2-3 changes ), aided by ultrasonic treatment for 5-10 mins each. This was followed by acetone 100% p.A ., a mixture of say 3% HCL in 95% ethanol for some minute (not too long!)[see below *)] , 1-2 times 100% Ethanol, and as the last step, 2 x 5-10 min petroleum benzine (e.g. Merck 1.01775, boiling point 40-60 degr.C [see below **) ]), decanting the fluid (use really "clean" glassware!!) and letting air dry (eventually using for that a laminar flow apparatus) the grids [most obviously stuck onto the wall of the inverted glass beaker) on a sheet of lint free lens paper (as used in TEM cleaning) until the grids have fallen to the bottom...otherwise use an antistatic gun for example).

When those cleaned grids were used again, I / we alsways found the grids to be observable with no problems of old contamination.

If you want to see what a company tells you about I recommend to read @ http://www.2spi.com/catalog/grids/grid-cleaning.html . And there are some other company websites dealing with such.

Remarks: *) long treatment of grids in an acid solution of HCl - Ethanol will corrode your delicate grids over / within a short time. So control the point where / when the grids become shiny and stop by another step (neutralization) with, say, 1 NaOH-solution (a.bidest!) shortly and rinsing thoroughly several times in A.bidest. before going on with 100% Ethanol,...,... In other sources / references one can find treatment of grids after dissolution in solvent (e. g. chloroform), using glacial acetic acid, and so on...

**) Disclaimer: no affiliation with SPI Supplies, no financial interest, just having read and thought over their advices,,,

Last but not least, I do have in file some advice for cleaning carbon coated grids...with the aid of a plasma cleaner .... but that would be a post too long here...so if you are interested in getting that information, please ask for it (or send an e-mail to [email protected] CAVE: *#*) , allowing to send some documents to your institutional or private e-mail address).

Have a great weekend....Christmas time approaching...

best regards,

Wolfgang.

*#*) EDIT 2019-04-15: Due to retirement and closing the EM-Lab meanwhile, the mentioned e-mail-Address isn’t functional any more. If you want to get information as offered:

Use either the ResearchGate-Messaging system or write an E-Mail to [email protected]. Thank you.

Thanks Wolfgang, Your answer is very clear to me. Carbon coated grids are not used by me, so the Plasma cleaning procedure is not required right now.

From this answer I learn that I will need many grids to make the cleaning profitable, still I will try soon. I rather not throw away the money that needs to be spend on research and health care, but you have to keep in mind that labour hours and cleaning chemicals are not for free either.

Happy holydays

Dear Duco, you're welcome.

Usually in our Lab such a cleaning "session" will be/was done once a year...(some 100 grids...)

All the best to you and yours,

Merry Christmas and a Happy, healthy, prosperous and successful New Year,

regards

Wolfgang

Hi! I have just a wee comment to add. I use big slot grids (2x1mm size) because my work depends on full view and often just take sample sections to check prior to doing either serial work or larger collections. To maintain stability of the formvar and be reusable, I use Synaptek grids. They are very stiff and heavy, and do not bend (beryllium alloy). *no financial interest* I'm just mounting sections that were stained en bloc, I don't get lead or UA on them, so I just clean them with a series of 0.1M HCl, water, and then 70% EtOH, though for something more sensitive you might have to do more.

They do cost more per grid, so that could be an issue, but I get many uses out of them. I'm more likely to lose one before it is bent or damaged in any way.

Hope this is useful! Happy Holidays!

We clean formvar/collodion carbon coated grids (ni or Cu) for sections or dips, with chloroform in a sonicator, for 10-15 min 3 repetitions, and a final wash with acetone. Then let dry in stove for a couple of hours.

Good luck!

Here in Detroit, Michigan, we have simply used chloroform and pulse sonication (gentle) for delicate gold grids.

Vickie Kimler

Hello Duco,

I have personal advise to you that please don't use "reuse formvar coated grids for your study.. As compare to the cost of doing EM ,using freshly coated grids are negligible . Reuse grids may give you bad results and you will waist lot of time and money by rectifying the same. So make adjustment of f your funding for buying fresh grids.

DR. PRAVIN D. POTDAR