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Re: [Microscope] Re: Zeiss lens cleaner

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  • pjifl
    There seem to be so many lens cleaning do s and dont s that one could be forgiven for thinking either it does not matter or they all work ! Many of the
    Message 1 of 46 , Mar 11, 2013
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      There seem to be so many lens cleaning do's and dont's that one could be
      forgiven for thinking either it does not matter or they all work !

      Many of the specific do's and dont's seem to relate more to the lens
      surroundings and coatings than the glass itself.
      And some of these do react slightly or even seriously with various cleaning
      agents that are fine on bare optical glass.
      Glass itself is rather tolerant to chemicals although some of the early
      exotics are more easily damaged. It is more likely to be damaged by
      abrasion than careful application of small amounts of chemicals. But don't
      use strong Alkalis for any extended period. Short exposure to weak Ammonia
      is OK on bare glass and modern coatings.

      Since varnishes, plastics, sealing compounds, lens edge blackening paints,
      dead black paint, lens bonding 'balsam', and coatings have changed over the
      years - and different makers may have used different materials, it may be
      quite important to refrain from using certain chemicals unless you confirm
      they are OK.

      A solvent that dissolves surrounding paint or plastic not only does damage,
      but drags smears onto the lens surface which are hard to remove.

      Another consideration is that solvent may wick into gaps and joints and be
      very hard to remove. And it sits there working on the plastics, sealants,
      and balsam lens cements.

      SO - I would take many recommendations relating to modern lens cleaning with
      caution. For example - most modern lens coatings are extremely hardy and
      will take a lot of scrubbing and strong chemicals. Some seem more hardy
      than the glass underlay. Yet one of the earliest coatings was Calcium
      Fluoride which is fragile. Some actual lenses were also made of CaF.
      Later, Magnesium Fluoride was very common. It remains in use today for the
      run of the mill lenses. Some of its application was poor and one has to
      be careful.

      It is interesting that the recently commented on ROR (Residual Oil Remover)
      seems to have a composition of

      Ammonia 0.8 %
      Sodium Chloride 0.8 %
      IsoPropyl Alcohol 4.3 %
      Liquid Soap 9 %
      Distilled Water 85%

      Which to me is very strange and I find it hard to believe.

      Why use distilled water then add NaCl which would leave a residue !
      Or was it really intended for contact lenses ?????


      One sometimes sees dire warnings against Ammonia. A small amount of weak
      Ammonia is excellent for removing oil and grease smears. And it seems to
      do no hard to modern multicoats and bare optical glass. But it would take
      off CaF coatings very quickly and possibly the MgF ones as well if
      prolonged.


      A very widely used lens cleaner is Distilled water, 5 to 10 % IPA, a few
      drops of Photoflow (memories - a detergent which seems to leave no residue)
      and a small dash of Ammonia if you like.


      An almost refreshing page on cleaning Televue products is at

      http://www.televue.com/engine/TV3b_page.asp?id=103

      But this may not be well suited to some older microscopes because Televue
      coatings are modern and the best.

      Windex, by the way, seems to now mean many different things. It once was
      close to the brew given above.

      Peter Smith
    • pjifl
      Bad form to reply to ones own emails but I said ... Should have mentioned for anyone wanting to trace this down most of the web material was about making
      Message 46 of 46 , Mar 14, 2013
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        Bad form to reply to ones own emails but

        I said

        >
        > On bare glass, one readily available agent that has been used by people
        > making photographic plates (like making the emulsion and coating the
        > glass)
        > is NapiSan. Or is it NappySan ?? The glass is simply left to soak in a
        > solution.
        > Because of the coating the surface needs to be very clean and it seems to
        > work. Somewhere there is web material on this.
        >
        > Also labelled as a Soaking and Cleaning agent in Supermarkets possibly to
        > bypass the above trade name.
        >
        > Anyway, it contains a high percentage of Sodium PerCarbonate which is a
        > strong oxidizer.

        Should have mentioned for anyone wanting to trace this down most of the web
        material was about making Plates for Holography.

        Peter Smith.
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