FP4 edge info very light

For those of you who develop your own film......

Wondering if what a lab told me is true.

I wrote to them because I noticed that the edge info for two 120 FP4 rolls (in same job sent to them) looked very different. On one roll, it was very faint, barely legible. I figured that meant that roll was underdeveloped.

Most of the the photos on that roll looked okay, but I always overexpose, which would compensate to some degree for underdevelopment. There were three photos on that roll where I accidentally did not overexpose (or possibly underexposed) which were thin.

The reply from the lab was: “Edge code density varies – I wouldn’t judge over- or under-processing by it. I checked the log book, and we ran your two rolls of FP4 together on the same rack – so, they were processed the same.”

Attached are photos of negs on my light table from the two rolls. The roll with the darker edge code has images with a lot of light colors which may contribute to the negs looking denser compared to the other roll.

The image in my first jpeg, on what I thought was an underdeveloped roll, doesn’t look bad in terms of density. But, as I said, I tend to overexpose. My third jpeg shows one of the images on that roll which is thin, where I must’ve not overexposed or possibly underexposed.

I haven’t checked all the FP4 film I’ve had developed over the years (at various labs), but I’ve checked about 15 rolls, and the edge info is not as light as the roll discussed here.

The edge info on the Tmax 400 sent with these FP4 rolls looks nice and dark, as has edge info on all the Tmax 400 and HP5 rolls they've developed for me in past six months.

If the rolls were truly developed at the same time, as lab said, it does seem an issue with Ilford. Has anyone seen this themselves? I’ve always looked at edge info for clues re developing.

Thanks for your input.

And, yes, I need to start developing my own film : )

P.S. Unfortunately, I don't have a record of lots the two FP4 film rolls came from. I was keeping a record of that for a while, when I was having another problem with FP4 (the mottling from backing paper).

I have had this issue with Pan F and it is film that has aged. The latent image, the edge markings, fade away. If you shoot it and wait long enough your image will also fade. Just a thought.

ags2mikon said:

I have had this issue with Pan F and it is film that has aged. The latent image, the edge markings, fade away.

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That's the first thing that comes to mind, yes. PanF+ is kind of notorious for this, but any film exhibits this phenomenon to an extent. IDK exactly where FP4+ fits on the spectrum. Given how faint those edge markings are, the film must have been pretty old; 15-20 years or so?

calico said:

Edge code density varies

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But generally not within the same film type and the same manufacturing era.

PS: development looks normal to me; perhaps a little on the brisk side. But it's always hard to judge density on photos of negatives. Anyway, I see nothing to worry about here.

koraks said:

That's the first thing that comes to mind, yes. PanF+ is kind of notorious for this, but any film exhibits this phenomenon to an extent. IDK exactly where FP4+ fits on the spectrum. Given how faint those edge markings are, the film must have been pretty old; 15-20 years or so?


But generally not within the same film type and the same manufacturing era.

PS: development looks normal to me; perhaps a little on the brisk side. But it's always hard to judge density on photos of negatives. Anyway, I see nothing to worry about here.

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The film most definitely was not 15-20 years old! If it was expired, it was not more than a few months expired. When I had the problem with the mottling in FP4, I became very careful to not use expired FP4, as Ilford said expired film more likely to have the mottling problem. I have allowed myself to use FP4 when it is maybe three months expired, not more.

Your comment that the fading generally would not happen "within the same film type and the same manufacturing era" would be relevant in my situation. Those two rolls of FP4 were certainly bought close in time to eachother (in past year? or two at most?)

ags2mikon said:

I have had this issue with Pan F and it is film that has aged. The latent image, the edge markings, fade away. If you shoot it and wait long enough your image will also fade. Just a thought.

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Aged how long? This roll would not have been more than a few months from expiration date.

When you say image will fade, too, do you mean if the film is shot but not developed?

calico said:

When you say image will fade, too, do you mean if the film is shot but not developed?

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Exactly.

This amount of latent image fading on film just a couple of months past its due date at the longest is not something I've seen before.
Since the images came out OK, I'd not worry about it, but if you're curious, you could contact Ilford/Harman and ask them if they have an explanation. It would help if you could supply them with batch codes on the film boxes - in case you happen to have saved them.

Miracle of miracles. I just checked my notebook where I note exposures and other info.

I have the info from the FP4 boxes for two rolls in question.

Roll with the light edge info:
05/2024 expiration
FF9331
Roll was shot 6/5/25, so a year and a month from expiration, longer than I had thought. Guess I decided to live dangerously : ) I had been so careful about not using expired FP4 when I was having the mottling problem (or I would only use if expired a few months).

Roll with darker edge info:
09/2025 expiration
FF2624/309/2025
Roll was shot 5/31/25

So the roll with light edge info was older than the other roll, about a year expired.

Interesting that being just a year expired would cause the edge info to get so light.

calico said:

Interesting that being just a year expired would cause the edge info to get so light.

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It's the best explanation we have, but I'm also highly surprised, especially since I've shot much, much more expired FP4+ that came out with much stronger edge markings.

Contact Harman.
IIRC, over the years they have made adjustments to the edge printing equipment.
And of course the equipment must be reset every time they edge print another type of film.
So the newer batch may have been set with the edge print settings set normally, while the older batch might have been made with the settings accidentally set for HP5+.

MattKing said:

And of course the equipment must be reset every time they edge print another type of film.
So the newer batch may have been set with the edge print settings set normally, while the older batch might have been made with the settings accidentally set for HP5+.

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So, Matt, does that mean that each setting is made so that it appears as a certain shade of black for a particular development time that the particular film needs in a standard developer, say ID11, so blacks for each film will be roughly the same for all types of film if correctly developed but accidentally using a higher speed film setting for HP5+ on an FP4 using a lower dev time results in the higher film speed edge setting coming out fainter since the FP4 needs much less development time?

I was thinking aloud here when I wrote the above as that was the way my logic seemed to be leading me based on what you said However I have just checked dev time for each film in ID11 stock and in fact HP5+ requires less time so if the HP5+ setting was used for an FP4+film then the extra minute needed for FP4+ applied to the HP5+ setting should have resulted in a darker edge marking not lighter?

I am confused. Really what I should be asking you to do if you will is explain as simply as possible how these settings you refer to are used and how they work

Thanks

pentaxuser

Along the lines of development times which pentaxuser brought up.....

The lab who developed these two rolls of FP4 uses Ilfotec DD.

(I think DD is the version of DD-X that labs use, because they use replenisher. Correct me if I'm wrong.)

Before I got the reply from the lab where the person claims the two rolls of FP4 were developed together, I checked development times in DD-X for HP5 and FP4 (assume times same for DD as DD-X, didn't see separate tech sheet for DD).

The time for HP5 at 400 ISO is 9 minutes. The time for FP4 at 125 ISO is 10 minutes. I wondered if the FP4 with the light edge info had accidentally been developed with the HP5 rolls they developed that day (ie, underdeveloped).

The person at lab claims the two rolls of FP4 were developed together, though.

BTW, thanks everyone for your input.

MattKing said:

Contact Harman.
IIRC, over the years they have made adjustments to the edge printing equipment.
And of course the equipment must be reset every time they edge print another type of film.
So the newer batch may have been set with the edge print settings set normally, while the older batch might have been made with the settings accidentally set for HP5+.

Click to expand...

Interesting.

But given that HP5 is developed less time than FP4, it seems if the edge info was set for HP5 on FP4 film, the edge info would be darker than usual if developed properly in FP4?

There's probably no way of knowing for sure what happened. Just trying to decide if I should keep sending FP4 to this particular lab.

Thanks everyone for your input.

calico said:

The time for HP5 at 400 ISO is 9 minutes. The time for FP4 at 125 ISO is 10 minutes. I wondered if the FP4 with the light edge info had accidentally been developed with the HP5 rolls they developed that day (ie, underdeveloped)

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pentaxuser said:

So, Matt, does that mean that each setting is made so that it appears as a certain shade of black for a particular development time that the particular film needs in a standard developer, say ID11, so blacks for each film will be roughly the same for all types of film if correctly developed but accidentally using a higher speed film setting for HP5+ on an FP4 using a lower dev time results in the higher film speed edge setting coming out fainter since the FP4 needs much less development time?

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It is amazing how complex people on Photrio like to make things .
The edge printing is simply an exposure on the film - historically through a changeable mask, but I think it now may be done with electronically controlled light sources that "write" the characters and symbols.
And the machines that do this need to be adjusted to the light sensitivity - the "speed" - of the film receiving the exposure.
So, for example, Delta 100 needs two stops more exposure than Delta 400.
The exposure is set fairly simply - just to whatever level will give the same nice black as you will see in a dense but not over-exposed highlight in any well exposed (at ISO speed) and appropriately developed negative, no matter what the film.
And that will be independent of the developer used!
Because if a properly exposed negative is properly developed in ID-11 at whatever that developer needs for the film, then it will be properly developed in DD-X at whatever that developer requires.
The contrast might differ slightly from developer to developer, and film to film, but edge printing isn't going to require fine tonality!

MattKing said:

It is amazing how complex people on Photrio like to make things .

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Agree. That's what makes these discussions so interesting!

MattKing said:

The edge printing is simply an exposure on the film - historically through a changeable mask, but I think it now may be done with electronically controlled light sources that "write" the characters and symbols.
And the machines that do this need to be adjusted to the light sensitivity - the "speed" - of the film receiving the exposure.
So, for example, Delta 100 needs two stops more exposure than Delta 400.
The exposure is set fairly simply - just to whatever level will give the same nice black as you will see in a dense but not over-exposed highlight in any well exposed (at ISO speed) and appropriately developed negative, no matter what the film.
And that will be independent of the developer used!
Because if a properly exposed negative is properly developed in ID-11 at whatever that developer needs for the film, then it will be properly developed in DD-X at whatever that developer requires.
The contrast might differ slightly from developer to developer, and film to film, but edge printing isn't going to require fine tonality!

Click to expand...

So with that info, my FP4 roll with the light edge info would not have had edge info mistakenly printed with the HP5 edge info setting. If it had, it would be darker than expected, not lighter.

From what everyone has said, either the edge info had faded -- even though the film was just a year + one month expired -- or the film was underdeveloped (which the lab denies).

Thanks.

calico said:

So with that info, my FP4 roll with the light edge info would not have had edge info mistakenly printed with the HP5 edge info setting. If it had, it would be darker than expected, not lighter.

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Nope.
HP5+ is two stops more sensitive to the exposure. So the setting for that would provide two stops less light than the setting for FP4+.
Meaning that if you put the FP4+ in front of the edge printer set to HP5+, your edge printing will end up two stops lighter.
If the same error was made the other way - the edge printer setting was left on the Pan-F setting instead of being switched to the FP4+ setting - the edge printing would be too dark, and probably blown out as well.

And if there is a full range of tones in the image bearing part of the negative, with contrast appropriate to the contrast conditions at the scene, then the film was probably developed properly.

But despite all that, you still really can't count on thoroughly reliable consistency when it comes to edge printing.
Particularly if the film has experienced adverse storage conditions prior to your giving it in-camera exposure, then the years old latent image that is the edge printing may very well deteriorate more than the rest of the film's light sensitive functionality might deteriorate. It is inherently unpredictable, even if it is rarely particularly important.

MattKing said:

Nope.
HP5+ is two stops more sensitive to the exposure. So the setting for that would provide two stops less light than the setting for FP4+.
Meaning that if you put the FP4+ in front of the edge printer set to HP5+, your edge printing will end up two stops lighter.
If the same error was made the other way - the edge printer setting was left on the Pan-F setting instead of being switched to the FP4+ setting - the edge printing would be too dark, and probably blown out as well.

Click to expand...

Okay, thanks. I was confused.

MattKing said:

And if there is a full range of tones in the image bearing part of the negative, with contrast appropriate to the contrast conditions at the scene, then the film was probably developed properly.

But despite all that, you still really can't count on thoroughly reliable consistency when it comes to edge printing.

Click to expand...

Didn't realize there were so many factors to consider when assessing the edge printing.

MattKing said:

Particularly if the film has experienced adverse storage conditions prior to your giving it in-camera exposure, then the years old latent image that is the edge printing may very well deteriorate more than the rest of the film's light sensitive functionality might deteriorate. It is inherently unpredictable, even if it is rarely particularly important.

Click to expand...

In the case of my roll under discussion, it was only one year old, not years old. But good to keep in mind that very old film might have faded edge info.

Thanks.

calico said:

Roll with the light edge info:
05/2024 expiration
FF9331

Click to expand...

calico said:

In the case of my roll under discussion, it was only one year old, not years old. But good to keep in mind that very old film might have faded edge info.

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A 2024 expiration date means it was probably manufactured in or around 2022 - so the latent image is around three years old.
A lot can happen to an image that is exposed in 2022, and not developed until 2025.
In most cases, the variability of three year old latent images isn't of concern. But if you are trying to draw inferences from the edge print density in the developed film, you probably should do so cautiously.
Particularly when it is film with backing paper.