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Hello dear Microscopy world!

Here at the facility we are observing corrosion of the "sealant" paint for the objectives.
Before testing every possible cause factor,  I was wondering if any of you already came across the same issue and could share with me his/her experience. From an online research I could  find no reference.

I am talking about the black/grey/whitish ring that is around the front lens, at the interface with the metal housing.

Our experience:
for water immersion objectives the paint is corroding and coming out in small pieces which get dragged on the lens when the objective lens is wiped. 
Observed for both Zeiss objectives and Leica's.

Our background data:
1) as immersion media for our water objectives we use either deionized water, milli Q water, or Zeiss Immersol W 2010.
2) the issue is observed also on a microscope where just deionized water is used (no Immersol)
3) users in the facility are instructed to use special lens paper and gently wipe the objectives when they are done, without adding additional media
4) cleaning of the lenses is performed regularly (on a weekly-biweekly base) by facility staff using hand-made cotton swabs, circular motion and the following solvents according to need: deionized water, isopropanol, high-grade purity ethanol, Zeiss mixture (85 % n-Hexan, 15 % isopropanol). Cotton is always used wet on lenses.


Thanking you in advance,
best greetings to all 

Aurora

-- 
Light Microscopy Facility
Max-Planck-Institute for Developmental Biology
Max-Planck-Ring 5
D-72076 Tuebingen
Germany

Phone:  +49 7071 601 1443
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