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. When
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
wiped
off before application of another drop before the next use.
	I don't take the breaking of legs literally, it just shows strong
emotions;
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 oils
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
bacteria,
neither will the drop hanging from the objective.

<They suggested using a cotton tipped applicator then use lens paper. But
never
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
previously
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, students
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
resulting
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 scopes
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  service@proscitech.com
Great microscopy catalogue, 500 Links, MSDS, User Notes
                      www.proscitech.com


>Date: Fri, 21 Jan 2000 14:35:55 +1000
>From: jim <jim@proscitech.com.au>
>
>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  service@proscitech.com
>Great microscopy catalogue, 500 Links, MSDS, User Notes
>                      www.proscitech.com

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.