Cleaning fingerprint on mirror

cprobertson1 · 11-30-2018, 02:29 AM

Oh no... I've gone and done it - I was changing lenses, got bumped by a passerby and grabbed the body to move it out their way... and got a fingerprint on the mirror!

Whoops!

"Auch well..." I thought to myself - "it won't affect the image quality - only the viewfinder!"

Which is correct... well, mostly...It's right in the middle of the viewfinder image and annoys me to no end! The smudge makes it hard for me to judge manual focus, and now that I think about it, it might be offsetting the metering too! Pfft! All in all, one of my more annoying "whoops!" scenarios that didn't actually involve breaking anything!

Well, what I wonder is what is the best/safest way to clean the mirror?

I've read on the photo.net forum the following method may work:

The method described in the post is as follows:

Originally posted by 2009, PTurton, et.al.:

1. Use a blower to remove any dust from the mirror.
2. Soak a Kodak lens cleaning tissue in ethanol. (Be sure that the ethanol used does not contain any oils such as may be present in "Rubbing Alcohol".
3. Carefully drop a layer of this tissue onto the mirror covering the finger smear.
4. Slowly drag the tissue off the mirror. The only pressure on the mirror will be the weight of the wet tissue and the surface tension of the alcohol soaked tissue across the mirror surface.
5. Repeat as necessary using a fresh ethanol soaked tissue to completely remove the smear.
I found that my mirror was cleaned by 3 applications.

On the face of it, this strikes me as a reasonable way of going about it - but I just wanted to check before doing anything in case there was a better method! I know the usual advice for cleaning the mirror is "don't" but I really want to get rid of this smudge and I'm not sure I can afford sending it off for professional cleaning!

Any help would be appreciated!

**rogerstg** · 11-30-2018, 11:01 AM

Originally posted by cprobertson1

I've read on the photo.net forum the following method may work

It makes sense to me. Alcohol is typically used in lens and sensor cleaning and the tissue is designed to avoid scratching and lint. I'll add that it's a good idea whenever cleaning something with solvent, to give it some time to do its work before dragging it off the mirror.

cprobertson1 · 11-30-2018, 11:11 AM

Originally posted by rogerstg

It makes sense to me. Alcohol is typically used in lens and sensor cleaning and the tissue is designed to avoid scratching and lint. I'll add that it's a good idea whenever cleaning something with solvent, to give it some time to do its work before dragging it off the mirror.

Good thinking! I'll get the lens tissues ordered asap and get on it!

**Bob 256** · 11-30-2018, 02:22 PM

That's the same technique for cleaning astronomical mirrors in telescopes and should work for you. The key thing is avoid anything that could have grit or residue in it so be sure to use lens cleaning tissue and good ethanol. Good luck.

PS: The sooner the better since the fingerprint can have acid in it which can etch the aluminum coating and leave a permanent mark.

amstel78 · 12-01-2018, 06:54 AM

I've cleaned many SLR and telescope mirrors this way and have yet to scratch or damage something. As long as you're careful and use clean lens tissues and the appropriate solvent, you should be good to go.

Wheatfield · 12-01-2018, 07:32 AM - **1 Like**

The method cited is, arguably, the best way, but I've had good success with a Q-Tip and lens cleaning fluid. The two things to be careful of is knocking the mirror out of alignment and scratching the front surface mirror.

cprobertson1 · 12-02-2018, 01:45 PM

There we go! Got it cleaned! Took a few tries because I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE!

See, the alcohol evaporates and leaves behind most of the water (it drives off a good portion of it though) - and it then evaporates and leaves a mark on the mirror!

So... I used 90% Isopropyl Alcohol to drive off the water - and IT dries clear at least...

Sheesh! That was dumb... I knew 70% leaves water as well... should have realised ::blushes::

**rogerstg** · 12-02-2018, 05:34 PM

Originally posted by cprobertson1

I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE!

At least you got it done and have a warning to others that might search this.

photoptimist · 12-02-2018, 06:56 PM

Originally posted by cprobertson1

There we go! Got it cleaned! Took a few tries because I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE!

See, the alcohol evaporates and leaves behind most of the water (it drives off a good portion of it though) - and it then evaporates and leaves a mark on the mirror!

So... I used 90% Isopropyl Alcohol to drive off the water - and IT dries clear at least...

Sheesh! That was dumb... I knew 70% leaves water as well... should have realised ::blushes::

We've all been there, done that!

When in doubt, put a drop of the proposed solvent on a plain piece of glass (e.g., an old filter), let it evaporate, and see if it leaves a ring.

cprobertson1 · 12-05-2018, 02:51 AM

Originally posted by photoptimist

We've all been there, done that!

When in doubt, put a drop of the proposed solvent on a plain piece of glass (e.g., an old filter), let it evaporate, and see if it leaves a ring.

Microscope slides would be a good test-surface for that now that I think about it! Cheap and easy to clean off if things go wrong, and no worry about scraping any coatings off during your tests!

11-30-2018, 02:29 AM	#1
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386	Cleaning fingerprint on mirror Oh no... I've gone and done it - I was changing lenses, got bumped by a passerby and grabbed the body to move it out their way... and got a fingerprint on the mirror! Whoops! "Auch well..." I thought to myself - "it won't affect the image quality - only the viewfinder!" Which is correct... well, mostly...It's right in the middle of the viewfinder image and annoys me to no end! The smudge makes it hard for me to judge manual focus, and now that I think about it, it might be offsetting the metering too! Pfft! All in all, one of my more annoying "whoops!" scenarios that didn't actually involve breaking anything! Well, what I wonder is what is the best/safest way to clean the mirror? I've read on the photo.net forum the following method may work: The method described in the post is as follows: Originally posted by 2009, PTurton, et.al.: 1. Use a blower to remove any dust from the mirror. 2. Soak a Kodak lens cleaning tissue in ethanol. (Be sure that the ethanol used does not contain any oils such as may be present in "Rubbing Alcohol". 3. Carefully drop a layer of this tissue onto the mirror covering the finger smear. 4. Slowly drag the tissue off the mirror. The only pressure on the mirror will be the weight of the wet tissue and the surface tension of the alcohol soaked tissue across the mirror surface. 5. Repeat as necessary using a fresh ethanol soaked tissue to completely remove the smear. I found that my mirror was cleaned by 3 applications. On the face of it, this strikes me as a reasonable way of going about it - but I just wanted to check before doing anything in case there was a better method! I know the usual advice for cleaning the mirror is "don't" but I really want to get rid of this smudge and I'm not sure I can afford sending it off for professional cleaning! Any help would be appreciated!

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11-30-2018, 11:01 AM	#2
rogerstg Loyal Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,168	Originally posted by cprobertson1 I've read on the photo.net forum the following method may work It makes sense to me. Alcohol is typically used in lens and sensor cleaning and the tissue is designed to avoid scratching and lint. I'll add that it's a good idea whenever cleaning something with solvent, to give it some time to do its work before dragging it off the mirror.

11-30-2018, 11:11 AM	#3
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by rogerstg It makes sense to me. Alcohol is typically used in lens and sensor cleaning and the tissue is designed to avoid scratching and lint. I'll add that it's a good idea whenever cleaning something with solvent, to give it some time to do its work before dragging it off the mirror. Good thinking! I'll get the lens tissues ordered asap and get on it!

11-30-2018, 02:22 PM	#4
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,378	That's the same technique for cleaning astronomical mirrors in telescopes and should work for you. The key thing is avoid anything that could have grit or residue in it so be sure to use lens cleaning tissue and good ethanol. Good luck. PS: The sooner the better since the fingerprint can have acid in it which can etch the aluminum coating and leave a permanent mark.

12-01-2018, 06:54 AM	#5
amstel78 Senior Member Join Date: Aug 2018 Location: NEPA, NYC, and wherever work sends me... Photos: Albums Posts: 247	I've cleaned many SLR and telescope mirrors this way and have yet to scratch or damage something. As long as you're careful and use clean lens tissues and the appropriate solvent, you should be good to go.

12-01-2018, 07:32 AM - 1 Like	#6
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,987	The method cited is, arguably, the best way, but I've had good success with a Q-Tip and lens cleaning fluid. The two things to be careful of is knocking the mirror out of alignment and scratching the front surface mirror.

12-02-2018, 01:45 PM	#7
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	There we go! Got it cleaned! Took a few tries because I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE! See, the alcohol evaporates and leaves behind most of the water (it drives off a good portion of it though) - and it then evaporates and leaves a mark on the mirror! So... I used 90% Isopropyl Alcohol to drive off the water - and IT dries clear at least... Sheesh! That was dumb... I knew 70% leaves water as well... should have realised ::blushes::

12-02-2018, 05:34 PM	#8
rogerstg Loyal Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,168	Originally posted by cprobertson1 I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE! At least you got it done and have a warning to others that might search this.

12-02-2018, 06:56 PM	#9
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,129	Originally posted by cprobertson1 There we go! Got it cleaned! Took a few tries because I used 70% Isopropyl Alcohol - AND THIS WAS A MISTAKE! See, the alcohol evaporates and leaves behind most of the water (it drives off a good portion of it though) - and it then evaporates and leaves a mark on the mirror! So... I used 90% Isopropyl Alcohol to drive off the water - and IT dries clear at least... Sheesh! That was dumb... I knew 70% leaves water as well... should have realised ::blushes:: We've all been there, done that! When in doubt, put a drop of the proposed solvent on a plain piece of glass (e.g., an old filter), let it evaporate, and see if it leaves a ring.

12-05-2018, 02:51 AM	#10
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by photoptimist We've all been there, done that! When in doubt, put a drop of the proposed solvent on a plain piece of glass (e.g., an old filter), let it evaporate, and see if it leaves a ring. Microscope slides would be a good test-surface for that now that I think about it! Cheap and easy to clean off if things go wrong, and no worry about scraping any coatings off during your tests!