Re: corrosion of objective "sealant" paint

[Aurora]

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Dear all,

I am bringing up again this topic with more information and with a better explanation (I see I was not clear enough).
I would be very surprised to hear that we are the only facility facing this issue!

On the following image you see which part I am talking about. It is just around the front lens.
https://drive.google.com/file/d/1kFBh6YdzRbgFnqbBm5vFUbLGYo344r3u/view?usp=sharing

The corrosion is observed happening quickly for water objectives, but, as you can see from the next 2 pictures, slowly it is happening also on our oil objectives.
https://drive.google.com/file/d/1DVwiRd71ypAu4InfnjdibRpN9NK34tEv/view?usp=sharing
https://drive.google.com/file/d/1iCwF81lQHv4006CA4rksaLBrpCP0gYjD/view?usp=sharing

My only bet so far, is that the deionised water that we use both for imaging and for cleaning it is not as "clean" as it is supposed to be, therefore we are going to switch to a new supplier and then monitor the matter.

Cleaning with pure cotton should not be the source of the problem, or at least, Zeiss swears that cotton is the only choice. And I actually don't have a better alternative.. using only lens cleaning tissue (as suggested by Dr Accardi) doesn't work for objectives in which the front lens is sunken (=at a lower level than the surrounding metal case).

Any feedback or suggestion would be much appreciated

wishing you wonderful scans,
cheers,Aurora

[Mark Cannell-2]

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Deionied water becomes more corrosive the purer it is. I've also seen damage due to the use of denatured alcohol.  I heard that a little sodium bicarbonate cab be used to inhibit clean water corrosion but don't know how much would be best but I'd guess <1 mM. It would also oppose the natural acidity of very pure deionised water.  YMMV and I hope this spurs more discussion on an very important issue!


Mark B. Cannell. Ph.D. FRSNZ FISHR
Department of Physiology, Pharmacology & Neuroscience
School of Medical Sciences
University Walk
Bristol BS8 1TD
 
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On 26/01/18, 8:42 AM, "Confocal Microscopy List on behalf of Aurora Panzera" <[hidden email] on behalf of [hidden email]> wrote:

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    To join, leave or search the confocal microscopy listserv, go to:
    http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
    Post images on http://www.imgur.com and include the link in your posting.
    *****
   
    Dear all,
   
    I am bringing up again this topic with more information and with a better explanation (I see I was not clear enough).
    I would be very surprised to hear that we are the only facility facing this issue!
   
    On the following image you see which part I am talking about. It is just around the front lens.
    https://drive.google.com/file/d/1kFBh6YdzRbgFnqbBm5vFUbLGYo344r3u/view?usp=sharing
   
    The corrosion is observed happening quickly for water objectives, but, as you can see from the next 2 pictures, slowly it is happening also on our oil objectives.
    https://drive.google.com/file/d/1DVwiRd71ypAu4InfnjdibRpN9NK34tEv/view?usp=sharing
    https://drive.google.com/file/d/1iCwF81lQHv4006CA4rksaLBrpCP0gYjD/view?usp=sharing
   
    My only bet so far, is that the deionised water that we use both for imaging and for cleaning it is not as "clean" as it is supposed to be, therefore we are going to switch to a new supplier and then monitor the matter.
   
    Cleaning with pure cotton should not be the source of the problem, or at least, Zeiss swears that cotton is the only choice. And I actually don't have a better alternative.. using only lens cleaning tissue (as suggested by Dr Accardi) doesn't work for objectives in which the front lens is sunken (=at a lower level than the surrounding metal case).
   
    Any feedback or suggestion would be much appreciated
   
    wishing you wonderful scans,
    cheers,Aurora
   

[Dan Focht]

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Aurora

It looks to me that you are seeing the chamfer around the perimeter of the lens.
It does not look like corrosion to me.
The perimeter of a lens is chamfered to reduce chipping at the interface of the polished surface and the edge.
By the looks of the metal surrounding the lens element this lens has had a hard life!
With that many scratches on the metal it is reasonable to assume that contact has been made with the delicate perimeter of the lens resulting in micro-chips forming.
I am willing to bet this lens is being used on an upright scope where a cover slipped slide is shuffled around under the lens having a close WD.
Inverted scope lenses get scratched also but usually not as bad.
On some lenses the chamfered area is covered with an epoxy, usually black, to not only protect the edge but also to reduce internal edge reflections in the lens.
I didn’t see any trace of residual coating in the pictures to indicate that this lens had such a coating.
I would like to see a picture of the exact same lens when it was new for comparison.

As for a safe lens paper you can’t beat berkshire lensx 90 <https://www.google.com/search?client=safari&rls=en&q=berkshire+lensx+90&ie=UTF-8&oe=UTF-8>.
Way softer than cotton and doesn’t leave fibers.
For concave lenses you cut the paper into 1.5” wide strips and wind it around a wooden stick about 1/16” diameter being carefully not to touch the leading edge of the wrapping.
Apply the liquid cleaner to the paper first then shake the wiper hard to through off the excess then wipe the lens.  
Note when cleaning lenses it is important to use both a water based cleaner to dissolve and salts or sugars that may have deposited on the lens and an oil solvent.
If you wipe an oil lens without a solvent it leaves a thin oil layer on the lens. When it is unused overnight or a weekend the thin film will slowly oxidize somewhat changing its refractive index and viscosity.
Then when you oil it up again the image has to pass through both the fresh oil and the irregular surface of the altered oil thereby reducing the resolution of the lens.

In a former life I was an optician then microscope serviceman before going into optical engineering and eventually micro-environmental control.

Dan  

> On Jan 26, 2018, at 3:41 AM, Aurora Panzera <[hidden email]> wrote:
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Dear all,
>
> I am bringing up again this topic with more information and with a better explanation (I see I was not clear enough).
> I would be very surprised to hear that we are the only facility facing this issue!
>
> On the following image you see which part I am talking about. It is just around the front lens.
> https://drive.google.com/file/d/1kFBh6YdzRbgFnqbBm5vFUbLGYo344r3u/view?usp=sharing
>
> The corrosion is observed happening quickly for water objectives, but, as you can see from the next 2 pictures, slowly it is happening also on our oil objectives.
> https://drive.google.com/file/d/1DVwiRd71ypAu4InfnjdibRpN9NK34tEv/view?usp=sharing
> https://drive.google.com/file/d/1iCwF81lQHv4006CA4rksaLBrpCP0gYjD/view?usp=sharing
>
> My only bet so far, is that the deionised water that we use both for imaging and for cleaning it is not as "clean" as it is supposed to be, therefore we are going to switch to a new supplier and then monitor the matter.
>
> Cleaning with pure cotton should not be the source of the problem, or at least, Zeiss swears that cotton is the only choice. And I actually don't have a better alternative.. using only lens cleaning tissue (as suggested by Dr Accardi) doesn't work for objectives in which the front lens is sunken (=at a lower level than the surrounding metal case).
>
> Any feedback or suggestion would be much appreciated
>
> wishing you wonderful scans,
> cheers,Aurora

Dan Focht
Bioptechs, Inc.
3560 Beck Rd.
Butler PA 16002
V724-282-7145
F724-282-0745
Toll Free 877 lIVE-CELL (548-3235)
[hidden email]