Archived posting to the Leica Users Group, 2002/03/04

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Subject: Re: [Leica] Removing Lens Coating
From: "John M. Sikes, Jr." <mcnaught@mindspring.com>
Date: Mon, 04 Mar 2002 16:18:20 -0500

Why do you want to remove a lens coating? Because it is 'old" or because it
is "defective", and does one relate to the other?

- ----------
>From: Dr.Alexander.Kraus@gmx.de
>To: leica-users@mejac.palo-alto.ca.us
>Subject: Re: [Leica] Removing Lens Coating
>Date: Mon, Mar 4, 2002, 2:42 PM
>

>>
>> >As a practicing dentist for the past 25 years, I can tell you that
>> >toothpaste not only will remove just about any lens coating, but will
>> also remove a fair amount of the lens element itself. You'll have a cloudy
>> lens in no time!
>
> I don't dispute the abrasive character of toothpaste. But I can also ensure
> you that I have sucessfully used toothpaste to remove an old defective
> coating without getting a cloudy lens. I used a special toothpaste for
senstive
> teeth which contain less pumice (or finer paritcles). One time I messed a lens
> up, but this was when I used a power tool for polishing. If you make a slurry
> of toothpaste and some water and wipe the lens without too much pressure, it
> takes quite a while untile the coating is polished of - and here we are
> talking about a layer of approx. 300 nanometers. I frequently check the
appearance
> of the surface and as soon as the coating is gone, I stop wiping the lens
> and wash the lens with water until the toothpast is completely gone. Even with
> a 10x magnifier I wasn't able to see any cleaning marks or cloudy surfaces.
>
>> >Toothpaste contains varying amounts of pumice and is very
>> >abrasive. I've seen patients over the years who are so aggressive with a
>> >toothbrush and toothpaste that they have removed tremendous amounts of
>> >tooth enamel such that the tooth has snapped in half due to
>> >toothpaste-induced erosion. Tooth enamel is far harder than any lens I've
>> >ever seen.
>
> What you describe is the result of years of abuse and the addtional impact
> of agressive chemicals (acids) that are formed in the mouth.
>
>> >As an aside, toothpaste can remove scratches in your car's
>> >paint or clearcoat quite nicely if used in small amounts on a wet rag.
>
> I know. Toothpaste is a perfect allround polishing aid :-)
>
> Alex
>
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Replies: Reply from Dr.Alexander.Kraus@gmx.de (Re: [Leica] Removing Lens Coating)
Reply from Javier Perez <summarex@yahoo.com> (Re: [Leica] Removing Lens Coating)