Artifact: What's the cause?

Simon R Galley

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Dear PE,

No apology needed...I like you do not 'understand' the 'motion' around the artifact thats why we have to have it looked at and checked out.

Simon. ILFORD Photo / HARMAN technology Limited.
 

David A. Goldfarb

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If agitation is by spinning the reels rather than inversion, that increases the likelihood of an airbell during processing, which could create that bidirectional comet effect.

How leaky is this tank? I haven't owned a Paterson tank for years, but as I recall, there's a gasket between the lid and the tank. Most tanks are a little leaky, so it's good to process over a sink and you might wear gloves, depending on what chemistry you're using, and just accept a little leakage, as long as it's not pouring out. For leakier tanks, I've just held a towel over the cap to catch the drips when agitating.
 
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Worker 11811

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I have communicated with Simon via PM and gave him all the details of the problem.
I have packaged the film and the negatives in question and they are on the way back to Ilford as we speak. He says that they will analyze the film and give a report in a reasonable time.

I told him that it is okay to say what the problem is even if it is due to a mistake on my part. I always say the only embarrassment is the mistake that is not corrected.
If I did something wrong, I will know not to do it again. Right?

I just want to say that Simon and all the folks at Ilford/Harman have been nothing but First Class all the way!

About the developing tank:
It is a "Costar" brand, Patterson style plastic tank with auto-loading reels. It is fairly old but it does not leak around the gasket. It leaks because the orange plastic top is cracked and does not seal well.

I used to agitate by inversion but have switched to spinning the reels due to the leakage.

I have had problems with recurring skin rashes in the past and have been advised to be careful around photographic chemicals. I almost always wear blue Nitrile gloves and am careful not to spill. I have not had problems with rashes lately but I still don't want to take chances. (Itchy, scaly rashes suck!)

I think I am going to switch to a stainless tank. I am replacing the lid and the reels on the one I have now. As soon as I receive them I plan to stop using the plastic tank. Aside from the leakage issue, the stainless tank only uses 250 ml. of fluid per roll vs. the Patterson's 300 ml. That's a 15% or better savings in chemistry. Every little bit counts. Right?

Bottom line: If I can switch to the stainless tank and avoid potential problems like this in the future, I'll be better off.
 

David A. Goldfarb

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Stainless tanks can often be leaky, but I've found that most of them improve with new Kindermann plastic lids, which you can get from B&H.
 

MattKing

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Photo Engineer

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I could not resist it.

If we got our emulsion mixers up to too high a speed, we decorated the lab! So, I imagined that!



PE
 

richard ide

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Randy,
Although I like your idea, electric drills are not suited for this because of the low RPM output.
If your lid was watertight, you could also agitate in the clothes dryer but ensure you use the cool setting only.
 

Anscojohn

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richard ide said:
Randy,
Although I like your idea, electric drills are not suited for this because of the low RPM output.
If your lid was watertight, you could also agitate in the clothes dryer but ensure you use the cool setting only.
Click to expand...

***********
Doesn't have to be a watertight lid--just hold the cap on tightly as you go around.
 
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Worker 11811

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Just want to update.

Got word back from the folks at Ilford. The verdict: Air bubbles.
They suggested the tank be agitated by inverting it instead of rotating the spindle. It was also suggested that a less aggressive agitation schedule be used. (4 turns in 10 sec. per each minute.)

I will also have to be sure I tap the tank when I set it down.
I do tap it. It's a habit. But I'll have to make double sure I do it more firmly and three or four times.

Thanks to all the folks who helped and to Sue, Neil and Simon at Ilford.

That kind of help really makes a difference!
 

Photo Engineer

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I am so very glad that it was not a defect in the coating as this would have been a first on APUG AFAIK with an Ilford product. They take painstaking care to prevent defects.

Now that we know what caused it, I can explain it to my own satisfaction.

A bubble formed and caused the center black (light on the negative) spot. Rotation of the reel back and forth moved the bubble and dragged developer byproducts back and forth forming a double ended comet simulating a coating defect of the same shape and size. So, I can see what went on in my mind's eye, and I agree with their solution. You (we) should not use back and forth rotation of the spindle.

My sincere congratulations to Ilford for superb customer service.

PE
 

2F/2F

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It is definitely not lens flare.

It looks like some sort of junk on your film during processing, or spots of incomplete development caused by air bubbles sticking to the emulsion during development.
 
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Worker 11811

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Yes, everybody whom I have conversed with has been absolutely top notch! :thumbsup:

I'm a little embarrassed because I didn't recognize the problem. Honestly, I have never seen air bubbles on film before. I have always thought of myself as being careful when I develop film. I know I tapped the container but I guess I didn't tap it enough. Eh?
Since I got the message back, I have been making sure to tap several times (3 or 4) times just to be sure.

How long do you think the air bell would need to exist in that spot to create that effect?
I'm going to guess it lasted for more than two cycles of agitation. (Longer than a minute.)

I guess the law of averages caught up to me. I would not say I am an expert but I have developed lots of film over the years. I always thought I was so careful. But I suppose, if one develops enough film, one is bound to see problems like this pop up at odd intervals regardless of how careful he thinks he is being.
 

Sirius Glass

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Per Volquartz recommends getting a thick rubber pad for cutting wood(?) blocks [it is about 1/4" {6 or 7mm*} of firm but soft rubber] from an art store, and thump the tank fairly hard several times [do not dent or crack the tank] several times when you first add each chemical]. I have not had a problem since I started doing this. Then again, I never had the problem before!

Steve

* for those of metric persuasion
 

Photo Engineer

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Randy;

That bubble may have been there for the entire development time. That is one reason I use a prewet. It tends to discourage bubble formation or retention.

PE
 

neelin

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Sirius Glass said:
Per Volquartz recommends getting a thick rubber pad for cutting wood(?) blocks [it is about 1/4" {6 or 7mm*} of firm but soft rubber] from an art store,
Steve
Click to expand...

Rubber gym floor is great too, and there are always scraps around. They are often left at jobsites (and then stored by the owner) as it's a expensive specialty product that never has too much waste on a job so it's usually not taken back by the contractor. There are various other types of rubber flooring around starting from 600mm square tiles up to about 2m wide rolls, but Gym floor is amazing.
 
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Worker 11811

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Photo Engineer said:
Randy;

That bubble may have been there for the entire development time. That is one reason I use a prewet. It tends to discourage bubble formation or retention.

PE
Click to expand...

I seem to remember that Ilford's documentation specifically recommends against presoaking, claiming that it can lead to uneven development.

I used to presoak all my films but stopped doing it after I read the datasheets. I believe Fuji has a similar recommendation in their datasheets.

It's a Catch-22. Isn't it?

Presoak against recommendations and risk getting uneven development or don't presoak, following recommendations, and increase the risk of getting air bubbles on the film.

What'cha gonna' do? :confused:

BTW: That rubber mat sounds like a good idea! I develop film in the laundry sink in the basement. It's the old, cement kind. It's a very hard surface. I keep imagining the nightmare scenario where the plastic canister cracks open when I hit it on the cement!

The rubber will help put that fear to rest.
Thanks!
 

BetterSense

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I had a problem where I got bubbles that looked exactly like that. Turned out it was spit getting on the film as I was putting it on the reels. The solution is not to yell at your wife or sing along to the radio while spooling up film.
 

Ian Grant

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A pre soaks not a cure for air bubbles, you can get far more in plain water than in a developer with it's sequestering agents and sometimes traces of wetting agent.

Sharp taps surprisingly don't remove all air bells particularly at the film/reel interface, I spent quite a while 2 years ago testing what was going on within my developing tank as I had major problems with the water here with it's heavy salt content. So I made visual inspections with & without film in a Paterson tank. I found that of all types of agitation twisting the spiral dislodged the most air bells, but non totally eliminated them. I don't use a commercial developer so there's no sequestering agents, etc so I took other steps, 2 drops of dilute wetting agent and that totally prevents air bells sticking during agitation.

Film emulsions contain surfactants (they help in coating) and those with higher levels tend to be less prone to air-bells. Some paper emulsions contain even more as it aids even processing particularly of FB papers and you notice the developer building up "detergent" like bubbles over a long printing session.

There's no easy cure, commercial film developers are designed to work with typical tap water, but in some areas tap waters not drinkable, and the high mineral content causes problems with developers and air bubbles. Using de mineralised or distilled water can be expensive in some parts of the world and not a viable option.

Agfa in particular did a lot of work in this area in the late 1920's early 30's, as did Kodak and Ilford slightly later, all had Patents for long chain wetting agents (that won't foam), but Dr Momme Andresen, Agfa (of Rodinal fame) wrote that a pre-soak was not the cure for air bells on plates around 1900 and in some cases can lead to uneven development. That's been the consensus of film manufacturers ever since.

Ian
 
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Photo Engineer

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In 1900, they used plain alcohols as quasi surfactants, they did not use "real" or should I say "modern" surfactants.

Surfactants are used in such minute quantity in coatings that they have little practical influence on development except in certain circumstances. They are (or can be) development accelerators. In some cases, a surfactant can actually promote foam (bubble) formation.

Therefore, under average darkroom conditions with modern films, a prewet has no adverse effect and only good effects in elimination or prevention of bubbles. I have used prewets for years and years with total satisfaction in both color and B&W and in formats from 35mm to 4x5.

PE
 
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Worker 11811

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Looks like I'm going to have to go back to the old practice of presoaking to see if it helps.

Looks to me like the benefits outweigh the risks, if any.
 

Photo Engineer

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Randy;

I suspect that some people give a long presoak and that might lead to problems. I suggest a 1 minute or less presoak. I use at least 2 changes of water at 100F and only 1 at 68F.

PE
 
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Worker 11811

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I always use 1 soak of 1 minute at whatever temperature the development is going to be. (e.g. A 68ºF soak for a 68ºF developer.)

The rationale I was taught was that it brought everything to the same temperature as the developer so that the thermal mass of the film, reels and tank would not affect the temperature of the liquid poured in.
I was also told it removes the antihalation dye if there is one.
Now, I also know that it prevents air bubbles from sticking to the film as well.

Sounds like there are more chips on the "presoak" side of the scale than there are on the "don't presoak" side, to me!

A 100ºF presoak? That sounds like you're just begging for reticulation to me! Really 100ºF?
 
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