Dots? What am I doing wrong here?

[rkm]

I've just got my scanner and have been working my way through 18 rolls of self-developed HP5. I'm consistently getting these dots appearing on the last five or so images on each roll.

My first thought is that it's bubbles in the development tank. I do four inversions per minute and tap the tank on the bench a few times after each set of inversions (apparently to displace bubbles). Maybe I'm not doing it aggressively enough?

My second thought is that when my negs are hanging in the shower recess to dry, the last negs are getting splashed by the odd drip from the shower head?

I'd appreciate some wisdom here, so I don't repeat my mistakes. Unfortunately I've ruined some nice images, and I don't want to keep on repeating my mistakes. Thanks.



Bubbles by

 

[kokoshawnuff]

If you use photo-flo (or something similar) there could be left over residue in the tank and on the reels from previous developing. No matter how many times you tap the tank, the photo-flo bubbles would remain and cause these spots. Always make sure the tank is really cleaned after developing, I typically leave the tank under running hot water for a few minutes after each development.

If you don't use something like photo-flo, then I have no idea what those could be since you already tap the tank after your inversions...

 

[Pablito]

use a wetting agent at the recommended dilution (or weaker), try drying outside the shower.

The fact that you are getting this on the last five frames only is weird, and suggests maybe the splatter from the shower head you suspect.

 

[rkm]

I have been using photoflo, and cleaning everything afterwards in a sink of hot water with a little bit of dish washing detergent. I suppose it could be residue from the photoflo or the detergent?

 

[kokoshawnuff]

I have been using photoflo, and cleaning everything afterwards in a sink of hot water with a little bit of dish washing detergent. I suppose it could be residue from the photoflo or the detergent?

After re reading I realize you say it's only on the last five or so frames, in which case residue might not be the issue (though residue on the tank might only attach itself to that section of film that is on the outermost circumference of the reel).

It just doesn't look like water spots to me (they're usually more organically shaped, not all circular), it looks like bubbles resulting from the developing process, and since you tap it on the counter after each inversion process it likely isn't the typical air bubbles one sees.

I had a similar looking issue once and came to the conclusion I just wasn't cleaning the tank well enough after the final photo flo process

 

[Dwig]

...I do four inversions per minute and tap the tank on the bench a few times after each set of inversions (apparently to displace bubbles). Maybe I'm not doing it aggressively enough?...

I think this is the issue based on the evidence and basic facts.

1. The spots are dark. This means that the spot is less dense than it should be. This is what would happen is an air bubble reduced developer contact for a portion of the developement cycle.
2. The sports have a bright ring. This is typical of an air bubble.
3. The spots are larger. Again, something an air bubble can be but residue isn't. When there is a large area of wetting agent residue it is usually an irregular blob and not perfectly circular.
4. Any residue from a wetting agent or other post developer step would be opaque or partially opaque. That would leave white spots, not dark. Spots from residue from overly concentrated wetting agent or excessively hard water are always white and very, very small.

Another possibility, though unlikely, is that some liquid was splashed or misted onto the surface of the film prior to developement that left droplets on the surface partially affecting developer penitration. Did you sneeze toward the film while loading the film in a darkroom? 🙂

BTW, wetting agent residue is always visible on the surface of the film. If you look closely at a reflection of a distant light source you will see the residue if it is present.

 

[rkm]

Thanks everyone for the advice. I'll be more aggressive in displacing air bubbles and see how I go. Strange that the bubbles are only on the last negatives, but it seems the most likely problem.

Another question. If you do get deposits of photoflo, is it possible to clean them off the negative after it has dried?