Effect of Prewash On Developer Activity

Chuck_P · Feb 21, 2025

In @What About Bob 's thread about BTTB I believe I saw that it was mentioned by someone that BT did not recommend a pre-wash when using the BTTB developer, so I have not been using a pre-wash with that process. However I don't know if that's because it is a two-bath method or if BT just never was a big fan of pre-washing his film with any developer. Any unevenness I've had using BTTB in the SP445 tank can be attributed to experimenting with B bath agitation schemes, imo. Until this thread, I've never really given my pre-wash (60 sec with gentle agitation) with XTOL single bath development a second thought.

I will say this, however, it seems my shadow placements without a pre-wash have been simply more robust looking than my shadow placements with pre-wash. Since the pre-wash might be reducing development across the negative, perhaps this is why. Perhaps it is in the shadows that this delay of development due to a water-soaked emulsion is showing itself more to my eye than in the high values when developing in a single bath developer. Idk, just a thought.

What About Bob · Feb 21, 2025

My theory about not recommending a presoak for BT2B might be to swiftly get as much developer into the emulsion; being that times in bath A are shorter than the standard D-23 development so maybe a presoak could lead to under-developed negatives, even though development is taking place in bath A.

John Wiegerink · Feb 21, 2025

I wasn't advocating a pre-wash/soak with BTTB or any 2-bath for that matter. I was just saying that a certain member on this site does use a prewash/soak with his 2-bath developer. It's for the same reason I use one with XT-3 R and that's because I don't want junk going back into my developer that I will reuse again.

Doremus Scudder · Feb 21, 2025

We've only peripherally mentioned the length of the presoak, and that only in relation to density changes during development, not in relation to uneven development.

I've found that some films require at least five minutes of presoak in order not to exhibit unevenness. Now, I don't use a lot of films, but even a few of the ones I use, a too-short presoak will cause uneven development. My SOP is now five minutes of presoak for everything.

IIRC, some films have surfactants incorporated into the emulsion. Soaking those only partially away seems like a good recipe for unevenness.

And, before anyone goes off about not presoaking: I develop sheet film by hand in trays using the shuffle method. The only way to do this practically without having the sheet film stick together in the development tray is to give them a nice, long presoak. I can introduce each sheet at 15-20 second intervals to the presoak and then get them all into the developer fast that way. I can't imagine having to keep track of timing on six sheets of film each introduced to the developer in 15-second intervals.

Best,

Doremus

ags2mikon · Feb 21, 2025

If I remember correctly, Jobo recommended a 5 min pre wash and I have followed that when I use the Jobo. I'm not near my main darkroom at present so I can't put my eyeballs on it.

grahamp · Feb 21, 2025

Jobo does suggest 5 minutes pre-soak - and based on some numbers posted here previously that sort of duration seems to be needed for consistency. Jobo also recommended up to 15% increase in development time with diffusion enlargers, so they acknowledge some contrast drop. Jobo were also covering colour processing temperatures, where film and tank temperature need to match process temperature.

I do not pre-wash reusable developers, such as BTTB, as there is a possible solution strength change. I do pre-wash single use solutions for 5 minutes. As long as I can get results I can work with, and like, I just aim to be consistent.

Now, if people are quoting development times for less common films or developers, the methodology should include pre-wash if used. It is basic information for others attempting to reproduce the results.

ags2mikon · Feb 21, 2025

I tried to omit the pre wash one time using px 125 and Perceptol and got streaking. Now I wish I didn't waste that roll. I miss that film.

John Wiegerink · Feb 21, 2025

ags2mikon said:
I tried to omit the pre wash one time using px 125 and Perceptol and got streaking. Now I wish I didn't waste that roll. I miss that film.

I miss it too! I didn't use it much when it was around since I was one of those Tri-X guys, but it was hard to beat in 120 size. Not only that, but I preferred it over FP4+.

ags2mikon · Feb 21, 2025

Just to keep on point, I also used it with Diafine without pre wash in the Jobo and never had any streaking. I used an EI of 320 and I thought it was as good as Tri x was at EI 1000 also with out streaking.

Augustus Caesar · Feb 21, 2025

koraks said:
Surface tension is a property of a liquid. It cannot be destroyed.

Well, if the film is dry, water will bead. If it's wet, it won't. That's what I mean.

Keith Tapscott. · Feb 23, 2025

Chuck_P said:
So what is Kodak's position on use of a pre-wash with their films, I can't see any reference to it in documentation that I have.

Kodak publication J-109 for Xtol developer suggests a one minute presoak for sheet films before developing in a dish/tray.

This is mentioned on page 3 of the publication.

Note that it only refers to sheet films, not 35mm or roll films.

dokko · Feb 23, 2025

Keith Tapscott. said:
Kodak publication J-109 for Xtol developer suggests a one minute presoak for sheet films before developing in a dish/tray.

This is mentioned on page 3 of the publication.

Note that it only refers to sheet films, not 35mm or roll films.

I just checkt several data sheets from Kodak. The XTOL ones (J-109) mention:

Agitating Sheet Film in Trays
Presoaking sheets in water yields more even development, especially when multiple sheets of film are processed together. Even a single sheet should be presoaked so that the rate of development will be the same as multiple sheets processed together.

the later ones mention a time of 1minute for prewetting.

the data sheets for T-Max, Tri-X and Plus-X mention:

Tray Processing—Sheets
Provide continuous agitation; rotate the sheets 90 degrees as you interleave them. Prewetting sheet film may improve tray process uniformity.

the D-76 data sheet (J-78) mentions:

To process 2 to 6 sheets together, follow the procedure below, which includes a prewet step. Prewetting will prevent the sheets from sticking together and will promote even development.

finally the publication O-3 has a detailed section on air bells, but none of it mentions prewetting as a solution:

Why Do Air Bells Form?
Air bubbles may simply cling to film surfaces when you first immerse the film in a processing solution. That’s why initial agitation to dislodge bubbles is so important.

Also, any condition that causes bubbles or foam in a processing solution can help to form air bells. All of the following factors can contribute to air-bell problems:
• overagitation
• equipmentthatdrawsairintosolutions
• use of solutions too soon after mixing
• temperaturechangesinsolutions
• insufficientfillingofclosedprocessingtanks
• incorrect filling of rotary-tube processors
• improperdistributionorleaksingaseous-burstagitation systems
• freeingupofdissolvedairwhencoldincomingwater warms to room temperature or is heated to provide hot water

How Do You Prevent Air Bells?
The most important factor is proper initial agitation. In batch systems, rap the reels or racks against the side of the tank to dislodge air bells carried in on the film. Agitating too vigorously causes bubbles to form. Agitating for too long a time can produce mottling.

In automatic processing systems, properly maintain the agitation system. In closed tanks and rotary-tube processors, be sure to observe proper filling procedures.

Treat dissolved air in a water supply by installing an aerator on the faucet. An aerator produces large bubbles, which rise to the surface and don’t adhere to the film. Allow cold tempered water to stand before using it; this will allow dissolved air to dissipate.

When the water supply is cold, you can minimize air bells by connecting 100 feet of coiled hose between the water supply and the chemical-mixing area or processor. The water will warm up gradually and the freed air will collect at the top of the coils, producing larger bubbles that won’t present air-bell problems.

Allow freshly mixed chemicals or chemicals diluted before use to stand for a time so that dissolved air can dissipate.

Chuck_P · Feb 23, 2025

Keith Tapscott. said:
Kodak publication J-109 for Xtol developer suggests a one minute presoak for sheet films before developing in a dish/tray.

This is mentioned on page 3 of the publication.

Note that it only refers to sheet films, not 35mm or roll films.

Cool, thanks! I don't have the XTOL data sheet but this is good to know.

Chuck_P · Feb 23, 2025

dokko said:
Tray Processing—Sheets
Provide continuous agitation; rotate the sheets 90 degrees as you interleave them. Prewetting sheet film may improve tray process uniformity.

Thanks, I totally overlooked this in my data sheet.

Sirius Glass · Feb 23, 2025

dokko said:
I just checkt several data sheets from Kodak. The XTOL ones (J-109) mention:

Agitating Sheet Film in Trays
Presoaking sheets in water yields more even development, especially when multiple sheets of film are processed together. Even a single sheet should be presoaked so that the rate of development will be the same as multiple sheets processed together.

the later ones mention a time of 1minute for prewetting.

the data sheets for T-Max, Tri-X and Plus-X mention:

Tray Processing—Sheets
Provide continuous agitation; rotate the sheets 90 degrees as you interleave them. Prewetting sheet film may improve tray process uniformity.

the D-76 data sheet (J-78) mentions:

To process 2 to 6 sheets together, follow the procedure below, which includes a prewet step. Prewetting will prevent the sheets from sticking together and will promote even development.

finally the publication O-3 has a detailed section on air bells, but none of it mentions prewetting as a solution:

Why Do Air Bells Form?
Air bubbles may simply cling to film surfaces when you first immerse the film in a processing solution. That’s why initial agitation to dislodge bubbles is so important.

Also, any condition that causes bubbles or foam in a processing solution can help to form air bells. All of the following factors can contribute to air-bell problems:
• overagitation
• equipmentthatdrawsairintosolutions
• use of solutions too soon after mixing
• temperaturechangesinsolutions
• insufficientfillingofclosedprocessingtanks
• incorrect filling of rotary-tube processors
• improperdistributionorleaksingaseous-burstagitation systems
• freeingupofdissolvedairwhencoldincomingwater warms to room temperature or is heated to provide hot water

How Do You Prevent Air Bells?
The most important factor is proper initial agitation. In batch systems, rap the reels or racks against the side of the tank to dislodge air bells carried in on the film. Agitating too vigorously causes bubbles to form. Agitating for too long a time can produce mottling.

In automatic processing systems, properly maintain the agitation system. In closed tanks and rotary-tube processors, be sure to observe proper filling procedures.

Treat dissolved air in a water supply by installing an aerator on the faucet. An aerator produces large bubbles, which rise to the surface and don’t adhere to the film. Allow cold tempered water to stand before using it; this will allow dissolved air to dissipate.

When the water supply is cold, you can minimize air bells by connecting 100 feet of coiled hose between the water supply and the chemical-mixing area or processor. The water will warm up gradually and the freed air will collect at the top of the coils, producing larger bubbles that won’t present air-bell problems.

Allow freshly mixed chemicals or chemicals diluted before use to stand for a time so that dissolved air can dissipate.

To prevent air bells, I thump the tank several rapid times on a hard flat piece of rubber, carving vinyl from an art supply store, just after filling with each liquid immediately after filling.

Effect of Prewash On Developer Activity

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