[rollei_list] Re: OT: Zeiss lens cleaning wipes?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Fri, 30 May 2008 03:47:32 -0700
----- 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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