First sign of oxidation on my ionic filter glass!

[Andy Perrin]

Well, I know I've been doing UV (etc.) photography for a while now (3+ years) because I just found the first signs of oxidation on my ionic glass filters. The S8612 was the worst, and then the UG11 and BG38. I cleaned them with the cerium oxide and microfiber cloth and it all came off nicely. My filters are nice and shiny again. If you've been doing this for a while, don't forget to look closely at your filters for oxidation issues!

[Hornblende]

How does oxidation affects the Baader-U?

[Andy Perrin]

A good question - it probably does not affect it because it's coated on both sides. There is only ionic glass in the middle.

[Cadmium]

Cleaning with hydrogen peroxide can be a good thing top try first, even better to soak the glass in it for a while first before trying to clean it. I usually use PEC pads for that.

If that doesn't work, then cerium like you explained.

Best to clean the filter as soon as you see any sign of oxidation. If it is left too long it can become a problem to clean.

[enricosavazzi]

How does oxidation affects the Baader-U?

At least in my case, not at all in my two specimens. They are at least 5 years old, and have been around the world quite a few times.

[dabateman]

How does oxidation affects the Baader-U?

 

In the 11 years I have owned my BaaderU filter, I have never seen oxidation on it.

This in cludes the last year where I dropped it and have a crack in it. I have sealed with small cut sections of black 3m electrical tape thst I know is uv black.

[Cadmium]

Has anyone ever given ultrasonic cleaning a try with camera filters?

Something such as this:

https://www.ebay.com/itm/NEW-PRO-LARGE-60-Watts-1-4-Liters-ULTRASONIC-ULTRASOUND-CLEANER-JEWELRY/380131255818?epid=2254425190&hash=item588196a60a:g:7yQAAMXQLs5RwOak

 

Also, important to point out, one should never use cerium oxide to clean a Baader U, or any other coated type filter, cerium should only be used with uncoated glass filters,

so be sure your filters are not coated in any way before you clean with cerium.

 

I am curious about the ultrasound, anyone try that?

[ulf]

I have not seen any oxidation on my filtes yet, only some accidental fingerprints, dust and smudges from pollen etc.

 

Ultrasonic cleaning is avery interesting idea, well worth trying, both for oxidation and dirt.

I wonder if it could be done without removing the filter's glass from the ring.

Then the polished glass surface would be better protected from scratching.

 

The liquid for ultrasonic cleaning can be more than water.

There are many specialised liquids and additives used for different kinds of cleaning.

When cleaning small parts in a big tank, the object to be cleaned and the cleaning liquid could be put in a ziplock bag, that can be immersed into the water in the big tank.

[ulf]

Cleaning with hydrogen peroxide can be a good thing top try first, even better to soak the glass in it for a while first before trying to clean it. I usually use PEC pads for that.

If that doesn't work, then cerium like you explained.

Best to clean the filter as soon as you see any sign of oxidation. If it is left too long it can become a problem to clean.

 

Is this undiluted 90% hydrogen peroxide?

"Hydrogen peroxide (formula H2O2) is a chemical compound that's a combination of hydrogen and water.

The clear liquid acts as a mild antiseptic and comes in various potencies depending on its purpose: 3 percent (household use), 6 to 10 percent (hair bleaching), 35 percent (food-grade) and 90 percent (industrial)."

 

Many years ago I used 90% hydrogen peroxide, concentrated Hydrochloric acid and water (1+1+3 parts) to etch DIY circuit boards.

Nasty stuff generating chlorine gas, but quite efficient for etching copper...

[Cadmium]

I have only used the household variety found in most stores, which is usually about 3 or 4 or 6% hydrogen peroxide to water.

You can get stronger % which is sometimes used in hot tubs, which is further diluted by the tub water.

Even the 3% variety will clean filters in many cases, and soaking will help with that process.

So soak your filter in HP, and then clean it with a PEC pad or something like a microfiber cloth, if that doesn't work then use some cerium.

 

But again, I would really like to try an ultrasonic cleaner. They use them for cleaning eye glasses... so why not filters?

[bvf]

My old U340 was beginning to go cloudy. I didn't fancy trying to polish it, so I bought another. I mentioned afterwards to the seller (I think it was image-laboratory, on ebay) of the 2nd one, and he suggested I soak the old one in baking soda. I couldn't find any baking soda in the kitchen, but I found some baking powder - which contains baking soda, but I was doubtful that it would work as it also contains tartaric acid. Anyway, I tried the baking powder, and it worked!

 

I've now bought some baking soda - not so easy to come by in the shops, so I got it online. A whole kilo of it. That should last for a lifetime of filters.

[Cadmium]

I have never tried baking soda, or backing powder for filter cleaning.

I had one of those little gray plastic submarines when I was a kid, I think it came in a box of cereal.

 

Here is a video, also explaining the difference between baking soda (sodium bicarbonate) and baking powder.

[bvf]

I didn't get your leap to plastic submarines, until I watched the video!

[dabateman]

Bernard,

Funny that you bought baking soda without testing it. It may work better, but I haven't tried either baking soda or powder.

 

I have two really oxidize Ug5 filters, so may give it a shot.

[bvf]

Well, the original advice was to use baking soda, so I thought I might as well get some - at £4.25 it wasn't exactly a big investment.

 

Of course, I haven't had cause to try it out since the baking powder success, so the baking soda will probably degenerate over the years and be ineffective when I need it. Mind you, I don't use the U340 and S8612 any more as I switched to the Baader U. So that baking soda probably was a complete waste of money.

 

I didn't have instructions of what to do, so I put a tablespoon of baking soda into a glass with an inch or two of water, stirred it, and left the filter in overnight.

 

If you do try it on the UG5, I'd be interested in hearing how you get on. If it works for you, perhaps I could sell it in ounce packs as MirakylFiltaKleen® for £9.99 a shot.

[Andy Perrin]

The Baader only works well for 60mm and up lenses though, I thought? Because of the dichroic angular dependence. Filter glass works even on wide angle lenses. Don’t toss those filters!

[bvf]

Good point. I use it with no problem on my 50mm Cassar S. I hadn't used it on my 35mm Kuri, but tried it just now and couldn't see any evidence of the dischroic problem at any aperture (although there was a slight off-centre hotspot at f/22).

 

But my full spectrum camera has an APS-C sensor, so these lenses are equivalent to about 55mm and 80mm - so perhaps I'm in luck.

 

But anyway, I wouldn't get rid of the old filters. The Baader U feels very light and fragile to me, so I'm sure I'll break it one day and will need a backup.

[enricosavazzi]

The Baader only works well for 60mm and up lenses though, I thought? Because of the dichroic angular dependence. Filter glass works even on wide angle lenses. Don’t toss those filters!

It depends on sensor size as well as lens focal length. 35-40 mm lenses usually work well enough even with dichroic-coated filters like the Baader U on Micro 4/3. On full-frame the limit is more like 50-60 mm as you mention, or 35-40 mm if one can tolerate some color shift between image center and corners.

 

Rear-mounting the filter between lens and sensor in most cases prevents problems with dichroic-coated filters regardless of lens focal length, especially when using legacy SLR lenses (which expect a distance between rear lens element and sensor/film plane of roughly 40-50mm).

[Cadmium]

I forgot to say, a few years back, someone told me that they soak their oxidized filters in vinegar to clean them.

I know nothing about that, I have never tried that, not endorsing that nor recommending that, just adding that to the list of things I have heard of.

[Andy Perrin]

Good heavens, is there anything people haven’t tried? Why not some Coca Cola?

[dabateman]

If it works for you, perhaps I could sell it in ounce packs as MirakylFiltaKleen® for £9.99 a shot.

 

Don't be mailing clear bags full of white powder to the USA. You might just get into some serious trouble.

[enricosavazzi]

Don't be mailing clear bags full of white powder to the USA. You might just get into some serious trouble.

Not just in the USA. Once in a while I buy small amounts of various chemicals to use in microscopy from eBay, often delivered in envelopes containing white powder or crystals in ziploc bags. Even for shipments within the EU, at least two-three times in the past year they were opened, re-bagged into "evidence bags" and presumably sampled and analyzed by Swedish customs and/or police. I don't really mind, except that the inspection adds about one month to the delivery time.

[ulf]

There is also a legal limit for the concentration allowed for hydrogen peroxide for private citizens in the EU.

The limit is 12%, as a higher concentration is considered as a precursor for making explosives.

 

From Steve's answer above, this is not a problem for cleaning filters.

[Cadmium]

Cerium should be pretty available in any country over the counter somewhere, like a lapidary supply store.

Hydrogen peroxide should be extremely common to purchase, almost any grocery store, etc..

[Cadmium]

Good heavens, is there anything people haven’t tried? Why not some Coca Cola?

 

Actually, Coke might just work. I believe it is on the acid side of pH.

Also, forgot to mention, some like to use toothpaste, being that it contains certain fine polishing abrasives such as cerium, but maybe not exactly cerium, maybe some other replacement that might be less expensive.

Some toothpaste, and I am thinking of Arm and Hammer specifically, I have seen one of that brand that also has Hydrogen Peroxide included in the mix, so it probably has a mix of Hydrogen Peroxide and fine polishing abrasive.

However, I prefer to use something that I know exactly what it is, like the real Cerium oxide.

Much of the cerium oxide sold on eBay (especially that from China) is not cerium oxide, or at least is only a very small % real cerium oxide, much is cut with other types of abrasive powders like Tin, Alumina, etc..

Real true cerium oxide comes in two grades, standard is pink in color, and optical grade is white. The white is a little more expensive, I can't see any difference in the polishing quality between the two, but I always use the white.