Sick S8612

[colinbm]

I have a very sick S8612, I bought it a number of years ago & I have had it in storage with plenty of silica gel, moisture satchels.

Last year I started to get my photography gear out of storage & I have been slowing putting things together to get back into invisible light photography again.

Well last year I found the S8612 filter was caked with a terrible coating.....:-(

I had known before that H2O2 will clean it, so I soaked it for a few hours, with no improvement. I tried to get it out of the filter ring with some specialist tools, but it wouldn't budge.

I soaked it some more over a couple of days without any improvement, then I tried some 'Windex' window cleaner, which made some difference, but I still couldn't get it out of the filter ring, in fact the grooves in the retaining ring were getting a rough time, so I left it.

Well today after a few months I tried it again...this time I used boiling water with some 'Windex' & after a lot of bad language & a lot of force I finally got the ring to shift. Looking at these images it appears that the ring was 'glued' into the filter ring, as there is a layer of some rubbery compound around the glass & in the filter ring...?

I will now have to soak the glass some more & then give the polishing compound a try.

Anyway here are some pictures of the 'sick' S8612...

WARNING, not for the faint hearted...:-(

 

 

 

 

[colinbm]

Did I say that there needs to be a solution found for this problem ?

I have a box of other filters that need cleaning too.....:-(

Some coating or sandwich ?

[Cadmium]

I think it is 6 years old. You might have a chance of restoring it with cerium oxide at this point, it is hard to tell.

It might be best to soak the glass in hydrogen peroxide more often before any problems develop.

After soaking, scrub it hard with hydrogen peroxide, PEC pad or microfiber cloth.

Repeat... if it doesn't work then use cerium oxide.

I think ITOS has coated S8612.

S8612 is one of the filter glass types that has no equivalent. Closest you get is Schott BG39 (or Hoya CM-500), or very thick BG40...,

but with those you get reduced UV bandwidth and peak.

I hope you can clean it up somehow. Let me know if you need help.

[colinbm]

I have plenty more, In fact I have a huge investment in glass filters & these at our specialist end seem to be the worst affected.

I will show my worse case filters, but I have 3x as many that are to bad to photograph with, representing a couple of thousand dollars.

Some of these filters are very similar or the same as the UV/IR cut (Hot Mirrors) filters used by our favorite camera manufactures......

My question has to be, why don't they, the UV/IR cut (Hot Mirrors) filters, degrade in our cameras, like our filters from different suppliers.

Surprisingly the Chinese ones are holding up better then my others sourced from western suppliers ?

 

[colinbm]

Here is the sticky substrate that prevented me getting the filter glass out of the holder politely, without destroying it....:-(

 

[Cadmium]

No idea about the white stuff.

[colinbm]

I have plenty of other filters labelled like this & very hard to turn the retaining ring to remove the filter glass to clean them, they were all bought around the same 6 years ago....

I wonder if there are others that have similar labels on their 'antique' 6 year old filters ?

Do any have 'glued' in glass ?

 

The problem is how to prevent this happening........silica gel has failed me...?

[Cadmium]

Clean them more often, or buy some that are coated.

[colinbm]

From where please ?

[Cadmium]

It makes no sense to me why there would be anything in the ring that has the white stuff in it, especially given that it has 51mm diameter glass in it.

Regardless of that, I will send you a small sample bottle of Cerium Oxide to try to clean those with, if you want me to.

Larger amounts of cerium are sold by various people on eBay in wet and dry form, and from reputable glass supply dealers.

If you get more, don't get the cerium from China, get some white stuff if possible from a good glass supply place.

 

I will also send you a new ring for the S8612 51mm diameter x 2mm thick circle.

And I will send you a new BG39 circle.

Like I said, if you want.

You need to clean those filters up.

 

There is a short list of filters that need to be cleaned regularly in order to maintain there longevity.

S8612, BG39, even BG40 and BG38 could uses such cleaning also.

Any U type glass, Schott, Hoya, and other brands too.

Schott UG1, UG2A, UG5, UG11.

Hoya U-360, U-330, U-340, etc..

The list goes on, but those are the most susceptible from my experience.

[colinbm]

I had to get the suckers apart first, & that has been impossible till now when I boiled the filter & I was able to move the retaining ring & damaging the rings & chipping the glass on another & I have a box full of the suckers to do....

I want to avoid the problem in the future........

[bvf]

Colin - you may want to try soaking in bicarbonate of soda (baking soda) as well - I've had some success with that. Baking powder (baking soda plus tartaric acid plus some other stuff) seems to work as well.

[colinbm]

Thanks Bernard, I tried that to a few months ago when you mentioned it, it was partially successful.

The biggest problem was getting it out of the ring, it was glued together.

I am really looking for a long-tern solution to keep them all squeaky clean & not getting the pox again.

What is causing the problem....air, oxygen, humidity, UV.....just what...?

[Andrea B.]

The problem is caused by the chemical instability of certain kinds of glass causing oxidation to occur over time. I suppose if you were able to store filters in a vacuum, then you could prevent the contact between air and glass. The only other option is some kind of coating, but that brings its own problems.

 

So, unfortunately for the pocketbook, filters do not last forever and must be replaced.

 

Best practice is to check filters once a month and get after any oxidation which might have occurred. Store them in airtight filter boxes with some silica gel packs. Even then, oxidation will ...eventually... happen.

 

You can use a big glass jar with a good, tight lid and put one of those rectangular 2x3" plastic silica gel packs in there with the filters which are in their little filter boxes. Those rectangular plastic silica gel packs turn pink when they have absorbed all the humidity they can absorb. You then bake them in the microwave or in a slow oven until they turn blue again. (Take care with the baking. I accidentally melted one once.)

 

Added: No, silica gel does *not* prevent oxidation. But it helps to some extent, especially with fungus.

[Andrea B.]

As far as we currently know, cerium oxide and hydrogen peroxide are the basis for the only two methods available (to us photographers) for serious cleaning of oxidation off uncoated color filters. There are other serious glass cleaners, but you would need to take your filters to the chem lab of a local university and find the lab manager who can access certain chemicals after perhaps you stand him a pint or two.

 

Also Note: Once oxidation has "eaten" into the filter glass, there's no hope for a clean up.

[Andrea B.]

UPDATE to my previous reply. Please see the vacuum sealer topic I started. I'm looking at this as a potential way to protect glass filters from oxidation. Two posts ago I said something about the possibility of vacuum sealing and then suddenly realized it might be quite easily done these days. :grin:

Linkie: https://www.ultravioletphotography.com/content/index.php/topic/3966-the-aha-moment-about-prevention-of-glass-oxidation/

[Stefano]

Do you want to run an experiment and see, a few years in the future, the result?

[Andrea B.]

Doing exactly that just now. (See link.) But it definitely does *not* take a few years to oxidize some of these filters!

 

I'm willing to bet good money that I leave my blue Baader filter out on the countertop and not in a box that I would see some oxidation on that thing within a month. :cool: Even when boxed up, I see oxidation on that blue filter about every 6 months. When we were staying in humid, coastal Maine in 2019 I found that two BG filters began to oxidize towards the end of our 6 weeks stay. They had been cleaned just before traveling there. I did not always clean and rebox those BG filters every time after using, so my laziness was at fault. But the point is that oxidation can occur more quickly than one would think under some conditions.

[colinbm]

Andrea has mentioned a good solution with vacuum sealing.

I wonder if the addition of oxygen & moisture absorbents are necessary too ?

[Andrea B.]

Adding an oxygen absorbing pack would be might be a good idea. I'll go mention that in the vacuum sealing topic.

[colinbm]

It would be nice though to isolate the cause & the unique solution though....?

[Andrea B.]

Have we not mentioned enough times that OXIDATION is the cause of a filmy cloud on some filters (not all)?

The unique solution would be to prevent oxygen atmospheric gases from coming into contact with filters.

 

The other serious problem with The oxidation problem with glass filters can be caused by MOISTURE in the atmosphere which can also make some filters (not all) leach alkalis and cause a kind of greasy deposit on the surface in high humidity or possibly crusty/crystalized deposit on the surface.

The unique solution here is to prevent moisture from coming into contact with filters.

 

Neither solution is particularly easy to accomplish. Best practice is to routinely inspect (say, once a month) and clean filters if there is any sign of degradation.

 

EDIT: 25 June 2020. It has been a long time since I studied Chemistry. I slightly edited my terminology to hopefully make the statements more accurate.

[colinbm]

Thanks Andrea

Yes the conscientious seems to be that it is oxidation, of what chemical composition ?

"Know thy enemy" seems to be the best defense, to win this battle.

We need to neutralize this enemy.

 

Yes I live in a hot humid area, but not as hot & humid as it can get, I only live halfway on the east coast of Australia, there is still plenty of country that gets hotter & more humid then here.

Moisture has been long branded as the culprit, but I have the filters with silica gel & the gel hasn't changed colour to tell me that it has finished absorbing the moisture....?

 

I am willing to donate my 'poxy' old BG39 filter & another older BG type filter for chemical analysis, if we have a chemist on board that is willing to look & sample these.

[colinbm]

Another reason that I question what is happening to our specialist UV photography filters, is that sometimes things are not as they seem....

Who knows that it is a bacterium that is eating away at the 'Titanic'....for instance...

https://en.wikipedia.org/wiki/Halomonas_titanicae#:~:text=Halomonas%20titanicae%20is%20a%20gram,the%20RMS%20Titanic%20in%201991.

[colinbm]

Manfrotto offer an affordable coating, 8 Layer Water Repellent Filter.......is this what we need for the BG filters ?

https://www.jbhifi.com.au/products/manfrotto-58mm-outdoor-uv-8-layer-water-repellent-filter