[rollei_list] Re: OT: Zeiss lens cleaning wipes?

Thanks Richard. I'll give it a go. I'm especially interested to see how it
will work with photoflo as I have not yet found 'flo ( + purifed water) to
be 100% effective in avoiding drying problems.
rgds
Chat

On Fri, May 30, 2008 at 11:47 AM, Richard Knoppow <dickburk@xxxxxxxxxxxxx>
wrote:

>
> ----- Original Message ----- From: <chatanooga@xxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Friday, May 30, 2008 3:03 AM
> Subject: [rollei_list] Re: OT: Zeiss lens cleaning wipes?
>
>
> Hi Richard
> I think you have also recommended isopropyl alcohol as something to add for
> the final rinse when washing film? Sounds like versatile stuff that I
> should
> try. Is it sold as you call it here or is there a product name?
> rgds
> Chat
>
>    Its sold as isopropyl alcohol or its newer chemical name isopropanol.
> For cleaning lenses or film it should be 99+%. The impurity is mostly water.
> If alcohol is left exposed to the air it will absorb moisture until it
> reaches 91% at which point its at equilibrium. The problem with alcohol that
> has moisture in it is that as the alcohol evaporates it leaves the moisture
> behind. You don't want this on lenses and certainly not for film because the
> moisture will cause streaking. This is Kodak's current recommendation for
> film cleaning but they warn not to use it on the support side because it
> will dissolve some film supports.
>   The trick of adding it to the final wash was told me by a Phd chemist I
> used to have considerable correspondence with some years ago. By adding it
> to a solution of Photo-Flo a sort of super wetting agent is formed. The
> Photo-Flo should be used at half strength and the alcohol added at about 30
> ml/liter of rinse. In this case you can use ordinary rubbing alcohol, which
> is usually 70%, because the water doesn't matter.
>   Isopropyl is relatively non-toxic and does not present an environmental
> hazard, however, it is inflamable, especially at 91% or stronger (used in
> alcohol lamps), and is rather irritating to the skin.
>   Other cleaning solvents recommended for film and lenses in the past have
> turned out to be either quite toxic (carbon tetrachloride) or
> environmentally damaging (1,1,1,trichloroethane).
>   Both of these were used for years because they are effective and
> non-inflamible.
>
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
> ---
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