Ethanol or methanol for sensor cleaning

Most of the recommendations I see here for sensor cleaning tend to

involve methanol.

 

Yes, one of the websites (the guys that market Eclipse) recommend

using ethanol over methanol.

 

Anyone know if one is better than the other for sensor cleaning?

 

I am going to be using it with Pecpads and a Sensor Swipe that I have

ordered from Copperhill. Cannot get Eclipse shipped to where I am,

so have to source locally.

 

Vandit

Good question. I know that one can actually drink ethanol (aka alcohol), unlike methanol which is harmful to humans. Do cameras care?.. that's the question

Methanol is a very powerful solvent and can dissolve silica, depending on what the sensor is protected with, you risk ethching it. I would stear clear of that.

 

Ethanol is may be denatured with some other chemicals to stop you from drinking it, so if it smells of anything don't tuch it, you risk leaving a deposit on the sensor cover. A good option is isopropyl alcohol (propan-2-ol), which is a lot less agressive and is relatively non toxic.

A clarification:

 

- actually, the recommendation against using methanol was from Visible Dust:

http://www.visibledust.com/faq.html#15

 

Peter & Vladimir - the recommendation against methanol was precisely b/c of its strong and potentially corrosive nature.

 

However, Eclipse is supposed to be methanol-based and almost every site cleaning website mentions using methanol.

 

Peter, I'll try isopropyl alcohol - I assume that is also residue free, just like 99.5% ethanol? Anyone here who has used either of these for cleaning the sensor and can provide a first-hand account of the experience?

 

Vandit

I would avoid liquids on a sensor for regular cleaning and only use it if everything else fails. If you really need a liquid i would follow Peters advise with isopropyl alcohol. Make certain that no liquid can get to other surfaces like between sensor and filter. (Normally "sensor cleaning" is cleaning the filter in front of the sensor.)

In the grand scheme of things, none of these are wildly different. Yes, methanol can attack epoxies, but it takes near to forever to do so. Methanol is extremely effective at removing old fingerprints, but the others are good enough. The real problem is getting any solvent in a purity high enough so as not to leave a film or residue. If I can find it pure enough, I prefer acetone, but watch out for plastics and painted surfaces. When ordering from a lab supply house, you want what's referred to as "spectroscopic grade". Anything you can get at the druggist or hardware store will be inferior. OTOH, if you don't know how to handle it, it won't be spectroscopic grade 30 seconds after you open the bottle and touch the top with a cloth or tissue. If you can find 91% or better pure isopropyl, that's reasonably safe and inexpensive. Everclear is supposedly a good choice, though I've never tried it. I wouldn't use methanol unless nothing else was effective, mostly because of toxicity. OTOH, if it were all that was available, I wouldn't hesitate to use it carefully. Caution- there may be differences in sensors, coatings, and construction, so any of these are at your own risk!

I've used labratory grade isopropyl. This is available from electronics supply stores and is

99.953 % pure.

 

Using a Q-tip dipped in the alcohol them rolled lightly in a Kleenex (white, unscented

only), small flashlight in hand to see well, using the lightest pressure, this works well and

quickly to remove things that don't blow off.

<em>Methanol is a very powerful solvent and can dissolve silica, depending on what the sensor is protected with, you risk ethching it. I would stear clear of that. </em>

<p>

Absolute crap I'm afraid, and I'm speaking here as someone with a Ph.D. in chemistry. Methanol is actually a fairly mild solvent. It's harmless to most plastics and totally harmless to glass and silica. It's excellent for cleaning optics, in fact it's the preferred solvent for the cleaning of very delicate laser optics, which are WAY more delicate than anything you'll find in a camera. Methanol is also quite good at disolving inorganic materials as well as orgainics, so it will remove things like salt (left over from fingerprints) as well as orgainics like grease (left over from fingerprints!).

<p>

The only downside of methanol is that it is toxic to humans, though you need to drink it or chronic exposure to do much harm. Using it to ocassionally clean optics is safe. Just don't drink it, take a bath in it or breath the fumes for hours each day.

<p>

Ethanol is actually a better solvent for organic materials, and again it's safe on most plastics and all glasses. It's also toxic in very large doses, though obviously not immediately a problem in small doses!

<p>

Bottom line - use ethanol or methanol, depending on what you have or what you can easily get. They're quite similar and both will be fine for sensor cleaning. Just make sure they are pure and leave no residue on evaporation.

<p>

The solvent to avoid is Acetone. It's a very, very good solvent for organic materials like grease - and most plastics, glues and paints. The problem with it is that it may dissolve the inside (and outside) of your camera it it comes into contact with it. It's also toxic in large enough doses. Unless you've poured hot tar on your sensor, you don't need Acetone!

<p>

I have a general article on optics cleaning <a href="http://www.bobatkins.com/photography/tutorials/lens_filter_cleaning.html"><u>HERE</u></a>

The main problem is getting a solvent with high purity so that it does not leave a residue, and one that does not readily degrade. The main use in cleaning sensors is to make dust particles stick to the cleaning pad, and only partly to remove other contaminents. A few drops are placed on the cleaning pad, and very little is actually deposited on the sensor.

 

Methanol is not an especially agressive nor corrosive solvent. It is readily available with extremely high purity for spectrographic or chromatography use. Methanol is widely used to clean laboratory optics. It has no effect whatsoever on glass - I have no idea where that "factoid" comes from. The chief contaminant of methanol is formaldehyde, which condenses in time to form paraformaldehyde, which would leave a white residue. Perhaps that is the source of this rumor. Methanol does not oxide readily to formaldehyde, so the initial purity is the most important factor.

 

Ethanol is hard to find with sufficient purity, due to tax reasons more than anything else. Isopropyl alcohol is a mild solvent, less polar than methanol, and would probably work. Again, the purity is an issue. Isopropyl tends to bead on glass and is slow to evaporate, and may pick up atmospheric contaminants in the process of drying.

 

I strongly recommend against using acetone anywhere near a lens. It attacks most resins aggressively and is usually contaminated with paraldehyde, which (like paraformaldehyde) leaves a white residue. Paraldehyde is a condensation product which forms on storage.

Bob, As another Chemist, I am surprised that you made the assertion.

 

Peter Meade is correct. Methanol does dissolve silica gel.

 

If you have done any column chromatography of natural products, you may recall that methanol was used as a final flush (being most polar). But any fractions needed to be reextrated with a non alcoholic solvent after evaporation of methanol because of the silica gel it brought down with it.

 

I can confirm that the Eclipse cleaning fluid does dissolve the low pass filter in my D70 and after every clean I can clearly see the blue-green color on the swab.

 

Just to confirm this, I tried the same fluid (Methanol) on various deep colored bandpass filters (R800, U-330 and the like)and yes there was deep red colors coming off of the filters. With a blue-green filter like the Schott BG-38 or BG-39 (similar to the low pass filter in D70/70s/50), there was blue coloration.

 

I switched to i-Propanol (iso-Propanol) which is less polar and hence less "corrosive".

Vivek, thank you for stepping in there. Bob, as someone who has supervised PhDs and has over 25 years laboratory experience in research chemistry, I know what I'm talking about.

 

P

Check the solubilities of Cobalt and Copper salts in Methanol. These are incorporated in glass to make the bandpass filters (IR cut and the like).

I use 99.5% methanol and don't have any problems. You can get from local chemical labs that cater to the public.

 

I'm suprised that the guys who market Eclipse would recommaned (If indeed they did) ethanol over methanol, since Eclispe is methanol-based.

 

KL

Ah, reading further, yes, I would see why the Visible Brush people would recommend against methanol -- if people stayed away from Eclipse, it's likely that more people would start looking into Visible Brush.

 

Funny how if you peel enough layers, personal agenda/personal gain always seem to come to the surface.

 

KL

Peter, We should get together for a game of Cricket! How good are you against spin? When I palyed for my school I used bowl off spin (I am right handed) and the wrong'uns (long before they coined names like "doosra"). :-)

 

Cheers!

Vivek, I can't bat, but I dow bowl leg spin. We could be the PN spin twins! !

I remember squat from my undergrad chemistry classes. But I can report that when I clean the sensor on my Canon 20D (and 10D before it) with Eclipse fluid and PecPads, there is zero coloration on the pad after swiping the sensor. Oh, yeah, and the dust is gone, too!

Vivek said :<i>I can confirm that the Eclipse cleaning fluid does dissolve the low pass filter in my D70 and after every clean I can clearly see the blue-green color on the swab.</i><p>

And I'm expecting my order of Pec Pads & Eclipse to arrive by courier within the next hour or two. $150.<p>

What to do today.....

KL IX: <i>Funny how if you peel enough layers, personal agenda/personal gain always seem

to come to the surface.</i>

<p>

The whole sensor cleaning industry seems to have more than its fair share of this. Claims,

counterclaims, weird claims, bogus claims... People seem to obsess over this - I won't say I'm

immune myself, I'm not - and the vendors know how to whip up our obsessions.

Ok, Spin Twins, so what is your consensus? 99.5% pure iso-propyl alcohol or ethanol going to be ok?

 

I'll try to see which one of these I can find readily...

 

Thanks guys for all the inputs.

 

Cheers,

Vandit

"What to do today....."

 

Seven, Use the Pec Pads. They are a very useful tool. Just don't use the Eclipse fluid. I have used it on my D70 a few times already with the PecPads turning blue. This would make the camera more useful for IR photography and obviates the need for a change of the IR cut filter.

 

Vandit, Yes. Safe bet is Iso-Propanol and Pec Pads.

 

[The IR cut filter in D70 (lower left, the circuitboard on the lower right is the CCD sensor with a new filter for IR) is a 1mm thick plain glass plate with a 0.1mm thick blue-green filter (looks like it is glued on the edges)on top. Extremely thin to begin with..]<div></div>

Methanol doesn't dissolve silica. I worked for 20 years on the properties of silica and I can assure you that it won't dissolve in methanol to any measureable extent. Now you can never say never and never say none. I guess and maybe you can get a couple of molecules of silica dissolved in anything, water and methanol included, but you cannot damage a lens or filter made of silica (or even most [any?] silicate based optical glasses) with methanol. I'd be hesitant to clean a fluorite element with methanol, but then again I'd be hesitant to clean one with anything. It's not very soluble in methanol or water, but I suspect there may be some slight solubility in polar solvents and both water and to a lesser extent methanol are polar solvents.

 

As I said, methanol is THE recommended solvent for cleaning laser optics. Recommended by the laser optics manufacurers themselves. Laser optics need to be perfect and laser mirrors need to be 99.99% reflective or the laser will not lase. They typically need to be at least 1/10 wave, preferably 1/20 wave or better. If methanol disolved silica or silicate glasses, or coatings on laser mirrors, they would be ruined. That's why you don't clean them with hydrofluoric acid, but you can soak them in methanol with no bad effects.

 

It is possible that methanol might dissolve some coatings which are applied to silica, but I doubt it. AR coatings tend to be materials like magnesium fluoride and they are also insoluble in methanol (and water). You could use coating materials which were soluble, but you'd have to be crazy to do that unless you needed some very special coating property. Even then you'd probably protect the soluble coating in some way by overcoating it.

 

If you have a red filter and cleaning it with methanol results in the cleaning tissue turning red, there's something wrong with the filter or it's made of methanol soluble plastic. Glass filters are not made of silica anyway, they're usually made of borosilicate glass like BK7 - but that doesn't dissolve in methanol either. I imagine gel filters are soluble in both methanol and water.

 

If someone can cite a scientific reference (and/or post a URL) to the solubility of silica (or other types of optical glass) in methanol, I'd be interested (and surprised) to read it.

"If you have a red filter and cleaning it with methanol results in the cleaning tissue turning red, there's something wrong with the filter or it's made of methanol soluble plastic. Glass filters are not made of silica anyway, they're usually made of borosilicate glass like BK7 - but that doesn't dissolve in methanol either."

 

Buy a Hoya U330 or a BG38 similar filter (no plastic and they have no coatings either)and try it out for yourself. Or else, borrow a D70 and clean its low pass filter with Eclipse.

 

I said Silica Gel in my post. "Silica" (fused silica or quartz, for example) is a different story.

 

Magnesium Fluoride can take up water. The durability of an AR coating from Magnesium Fluoride would depend on its structure. Not all AR coatings using MgF2 are the same. Their mechanical (scratch resistance) and chemical properties depend on their surface morphology.

When I purchased my Pansonic/Lumix FZ-30 camera, which sports a lovely Leica lens, I immediately purchased a Tiffen Standard Hot Mirror Filter to place on the lens since I discovered that the sensor of this camera was very "hot" to Infrared radiation and I would see lots of annoying "purple fringe" in my high contrast images.

 

Well, I managed to stick my fat thumb on that filter and used the Eclipse solution with the Pec Pads to clean it up. I'm happy to say that there was NO color transfer from the filter to the Pec Pads. Maybe everyone having color bleed problems with their Hoya filters should try Tiffen instead? ;)

I just bought some cleaning kit for my sensor from kinetronics with

an isopropanol based liquid.

I cleaned my D70 sensor with it and their special "qtips" which came

with it. I even had that slightly blueish/greenish tint, even if it

was just isopropanol...

I then used normal qtips, which seem to be softer, and got my sensor

perfectly clean now. Though I'm afraid if that cleaning with that

qtips from kinetronics could've caused some damage, or is the

difference that small that I won't see it? (I didn't rub of that much

of the filter)

Hope I won't have a bad surprise when I shoot the next time at sunny

days....