Re: FW: oil immersion lens cleaning

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From:Robert Schoonhoven <> (by way of Marvin Hanna)
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Having several microscopes within my "domain" both inverted and
'standard' I am in agreement with Ian, i.e.:
broke the fingers of a post doc a few years ago (NOT true!) that didn't
clean the oil off of the immersion lenses of the microscope in my
office.  The rule here is that NO ONE uses a scope until they have
learned to operate and clean it, and yes dust DOES get in the oil.  I
have never (in 25+ years) seen bacteria in immersion oil, dust (or crud)
yes, bacteria no.  Not saying that it couldn't happen mind you, but I've
not seen it.

As an aside,  would you northerners kindly keep the snow and ice on your
side of the Mason-Dixon Line.  Darn kids haven't been in school for a
week and they are driving me nuts.  More snow and freezing rain
predicted for this afternoon....... Have Jeep, will go to work for some
peace and quite.

jim wrote:
> Somebody defined religion as: "that about we ultimately care most".
>Clearly for
> some people cleaning of lenses has religious connotations.
> >Dust, it's terrible stuff and likes to stick and embed itself into
> >immersion oil. In multi-user labs the best policy is definitely CLEAN THE
> >MICROSCOPE OR I'LL BREAK YOUR LEGS. Immersion oil left on inverts is a
> >nightmare. eventually it creeps down the side of the lens and if its
> >sprung, into the innards then does horrible things. Result, a new lens.<
> Any dust would adhere to the outside of the oil drop. Its too viscous to
> readily mix. That is good, because that dust does not adhere to the lens.
> the excess oil is wiped off before a new drop is applied, the foreign
>matter is
> wiped away without scratching the lens.
>         Inverted optics are uncommon. If the recommended highly viscous
>oil is used,
> there should be no problem with this running. Again, excess could be just
> off before application of another drop before the next use.
>         I don't take the breaking of legs literally, it just shows strong
> how about some reasons. If the oil is wiped before use, the correct viscosity
> oil is used and only the required amount is re-applied no excess will
> accumulate. The only difference in fact is that the lens is not constantly
> rubbed with tissues and solvents.
> <I do know this - bacteria DEFINITELY live in oil.>
>         True, in crude oil, which is broken down by sea, air and sun,
>some bacteria
> thrive and help the breakdown. We are talking about immersion oils. Bacteria
> would survive in that for a time, but they certainly do not grow in numbers.
> Otherwise we would have quite a problem in keeping all stock of immersion
> sterile. Many labs have 10 year old bottles of these oils and they are
>clean as
> . . .Since the oil within the non sterile vial/bottle is not blown by
> neither will the drop hanging from the objective.
> <They suggested using a cotton tipped applicator then use lens paper. But
> use
> kimwipes. They said this will damage the coating that is but on the lenses.>
>         They "was wrong". Cotton wool is a dust/lint producer and as I
> noted, can contain some Si particles (its grown in soil!). Polishing
> microscopic gold particles for micro analysis is about the ultimate test of
> polishing media. Be assured, on a microscopic scale cotton is apt to scratch,
> not so Kimwipes.
> Actually, I don't have strong feelings on "to clean or not to clean", what is
> interesting are the strong feelings about this minor issue. Although,
> and incompetents who apply oil to the high dry lens and cover a scope in oil
> are irritations. Using a very high dry lens is a solution only if the
> lower resolution is acceptable.
> My thesis: If in a busy path lab for a ten year period three new scopes
>had the
> oil immersion lens never solvent cleaned, but in normal operation just the
> excess drop wiped off before application of a new drop, those lenses would be
> as good, or even less likely to be scratched than three lenses on other
> that were frequently solvent cleaned.
> Cheers
> Jim Darley
> ProSciTech                 Microscopy PLUS
> PO Box 111, Thuringowa  QLD  4817  Australia
> Ph +61 7 4774 0370  Fax:+61 7 4789 2313
> Great microscopy catalogue, 500 Links, MSDS, User Notes
> >Date: Fri, 21 Jan 2000 14:35:55 +1000
> >From: jim <>
> >
> >I love these free-reigning discussions with lots of assertions. Here are
> mine:
> >
> >I suspect there are a few don'ts for cleaning those lenses and the rest does
> >not matter.
> >
> >Pouring xylene all over the lenses and using abrasive papers are no-nos.
> >
> >Lens paper works, but is less absorbent than Kimwipes are. A few years ago
> the
> >local university's microscope maintainer returned from a "study tour" from
> >Zeiss and reported that they were using Kimwipes. Kimwipes are low lint and
> >contain no hard particles. Cotton can retain bits of silica from the soil
> since
> >its a natural product.
> >
> >Another correspondent asserted that cleaning oil off lenses frequently is
> most
> >important? Maybe it is, but why? The oil is essentially non-drying. The oil
> >immersion lens is only ever used with oil. The oil does not attack the
> cement.
> >It seems to me that the cleaning (other than wiping off excess oil prior to
> >applying a new drop) is not required, it does not improve resolution and the
> >process could cause damage. Why clean frequently; please give reasons!
> >
> >I claim no conflict: PST sells Kimwipes and Lens Tissue!
> >Cheers
> >Jim Darley
> >ProSciTech                 Microscopy PLUS
> >PO Box 111, Thuringowa  QLD  4817  Australia
> >Ph +61 7 4774 0370  Fax:+61 7 4789 2313
> >Great microscopy catalogue, 500 Links, MSDS, User Notes
> >            
> Jim,
>         Dust, it's terrible stuff and likes to stick and embed itself into
> immersion oil. In multi-user labs the best policy is definately CLEAN THE
> MICROSCOPE OR I'LL BREAK YOUR LEGS. Immersion oil left on inverts is a
> nightmare. eventually it creeps down the side of the lens and if its
> sprung, into the innards then does horrible things. Result, a new lens.
>         What do I use, lens tissue and ether or lens tissue and light
>breath. I've
> recently spoken to a Zeiss engineer who told me that the multi-purpose
> wipes for computers etc. are good for the first clean then finish off with
> lens tissue and light breath.
> Ian.

best regards,
Robert Schoonhoven
Laboratory of Molecular Carcinogenesis and Mutagenesis
Dept. of Environmental Sciences and Engineering
University of North Carolina
Chapel Hill, NC 27599
office 919-966-6343
   Lab 919-966-6140
   Fax 919-966-6123

Don't go around saying the world owes you a living; the world owes you
nothing; it was here first.
Mark Twain [Samuel Langhornne Clemens] (1835-1910)

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