Effect of Prewash On Developer Activity

[koraks]

Could a pre-soak do something to the AHL (which then does something to development)?

It generally dissolves any AH dyes if those are present in the emulsion. Sensitizer dyes as well. I don't think this does anything w.r.t. actual development.
In 35mm film, anti-halation measures are often an integral part of the film base and will remain unchanged forever. In 120 and sheet film they are often present as a soluble dye in the anti-curl emulsion on the backside of the film. AFAIK those dyes do not interact with development in any way.

 

[Harry Callahan]

I see.

 

[ic-racer]

Another aspect of prewash is a notion that it either promotes or inhibits even development.

One might think, since the swollen/pre-soaked emulsion is a little 'insensitive' to the first splashes of developer that come in the tank, evenness of development might be promoted.

On the other hand, some manufacturers, like Ilford, recommend AGAINST it:

A pre-rinse is not recommended as it can lead to uneven processing. -- ILFORD HP5 pdf

 

[Augustus Caesar]

Another aspect of prewash is a notion that it either promotes or inhibits even development.

One might think, since the swollen/pre-soaked emulsion is a little 'insensitive' to the first splashes of developer that come in the tank, evenness of development might be promoted.

On the other hand, some manufacturers, like Ilford, recommend AGAINST it:

Well, Ilford are wrong!

 

[MattKing]

Well, Ilford are wrong!

I have a feeling that the people at Harman, and the people who were at the former Ilford, have/had direct and vicarious experience with many more different types of developing equipment and procedures than any of us do. And I would expect that this warning flows from the results of some such equipment/procedures exhibiting uniformity problems, even if not every type of equipment/procedure exhibits such problems.
Manufacturers' recommendations are usually very conservative.
IIRC, former Harman director Simon Galley posted on this very issue with something to the effect of "do whatever works for you", but further posted that Harman did not intend to change their recommendation in the datasheet.

 

[chuckroast]

Well, Ilford are wrong!

I have no particular dog in this hunt. I've done it both with- and without prewash with no notable differences, except - as covered up thread - some slight decrease in contrast when prewashing.

Howsomewever ... could you care to share your basis/credentials/experimental data as the OP has to explain how you know better than Ilford? I am not much for argument from authority, so Ilford isn't automatically right, but you must have some reason for saying this.

 

[Augustus Caesar]

I have no particular dog in this hunt. I've done it both with- and without prewash with no notable differences, except - as covered up thread - some slight decrease in contrast when prewashing.

Howsomewever ... could you care to share your basis/credentials/experimental data as the OP has to explain how you know better than Ilford? I am not much for argument from authority, so Ilford isn't automatically right, but you must have some reason for saying this.

I use Paterson tanks, have for 50+ years. These are the older ones, with the small tops. I urge everyone, using any type of tank, to fill the tank completely, leaving just a little air space at the top. I fill the tank with water (same temp as developer, 68F) agitate, and let it sit for a few minutes. I then drain the tank and allow it to rest upside down on the table to drain thoroughly. I use a towel folded up on top of the table. After a minute or so of draining from the pre-wash, I pour the developer in, leaving only a small amount of air space at the top. I then place the cap on and invert the tank while rotating, then rap the tank firmly on the table (covered with a towel). Don't do it too hard or you'll break the plastic!
I agitate in this manner for about 30 seconds continuously, then invert/twist twice at 1-minute intervals, rapping the tank firmly at the end of each cycle.

Before I started doing this, I would get air bells. Now, never.

It is my understanding that pre-wetting the film prevents air bells from forming by destroying the surface tension.

 

[ic-racer]

I have no particular dog in this hunt. I've done it both with- and without prewash with no notable differences, except - as covered up thread - some slight decrease in contrast when prewashing.

Howsomewever ... could you care to share your basis/credentials/experimental data as the OP has to explain how you know better than Ilford? I am not much for argument from authority, so Ilford isn't automatically right, but you must have some reason for saying this.

I do stand by my original statement "...it [prewash or presoak] either promotes or inhibits even development"

 

[Augustus Caesar]

I do stand by my original statement "...it [prewash or presoak] either promotes or inhibits even development"

Schrödinger would disagree.

 

[Harry Callahan]

Another aspect of prewash is a notion that it either promotes or inhibits even development.

One might think, since the swollen/pre-soaked emulsion is a little 'insensitive' to the first splashes of developer that come in the tank, evenness of development might be promoted.

On the other hand, some manufacturers, like Ilford, recommend AGAINST it:

Hm... in the other topic Chuck_P is using a two bath developer and is getting uneven development. Could bath A act as some sort of "pre-wash" and by that cause uneven development?
...

Also i think i see an analogy between pre-wash/no pre-wash and agitation.
If you use continuous agitation, there will be more density on highlights. If you use semi-stand or stand there will be less density on highlights.
Without pre-wash there is less density on highlights, while with pre-wash there is more density.
Pre-wash seems to act like more agitation - and more agitation does exchange exhausted developer for fresh developer quicker.
It seems like pre-wash does just what it is intended to do, seems like pre-wash does help fresh developer to enter the emulsion better. Of course there is a delay in time, as the soaked water needs to be replaced by the developer first - but if this delay is compensated, highlights get higher density and therefore better supply of developer.

 

[chuckroast]

I use Paterson tanks, have for 50+ years. These are the older ones, with the small tops. I urge everyone, using any type of tank, to fill the tank completely, leaving just a little air space at the top. I fill the tank with water (same temp as developer, 68F) agitate, and let it sit for a few minutes. I then drain the tank and allow it to rest upside down on the table to drain thoroughly. I use a towel folded up on top of the table. After a minute or so of draining from the pre-wash, I pour the developer in, leaving only a small amount of air space at the top. I then place the cap on and invert the tank while rotating, then rap the tank firmly on the table (covered with a towel). Don't do it too hard or you'll break the plastic!
I agitate in this manner for about 30 seconds continuously, then invert/twist twice at 1-minute intervals, rapping the tank firmly at the end of each cycle.

Before I started doing this, I would get air bells. Now, never.

It is my understanding that pre-wetting the film prevents air bells from forming by destroying the surface tension.

That's certainly your experience, but I don't think you can generalize from that.

I have both done prewashing and not done prewashing and have never had an air bell. I always tap after every agitation, but I am using Nikor tanks and reels.

This suggests that the variable here isn't likely the prewash (or not) but either our tapping techniques or the tank/reels themselves.

This sort of makes sense to me. In my explorations of long development times/log agitation times, I found that plastic reels (or any other film support with plastic ridged walls) tend to trap liquid and/or not flow cleanly. With low agitation, this expressed itself as bromide drag. It might also be the source of air bells, I dunno.

I do "tap" or "rap" pretty aggressively after every agitation, though, so as to dislodge any air trapped along the film surfaces, so that could also be why I've not seen the problem.

In any case, I am not convinced that prewashing prevents air bells, but I don't discount that's a possibility when using the Patterson system.

In any case, I am inclined to believe Ilford. They know a bit about film processing


BTW, we've been here before:

Is there any possible harm to pre-wash before developing?

I just developed first ever roll of Tmax and, of course, it came out with the typical pink... unless steps are taken to correct, like pre-wash, longer fix, longer rinse, I learn. I am familiar with pre-wash, as I have been working with Arista, and its sheds its green stuff that way. So...

www.photrio.com

 

[John Wiegerink]

Some folks even use a pre-bath/soak when using 2-bath developers like BTTB. I don't! I always use a pre-bath when using Pyrocat-HDC. Why? Because it was recommended by Sandy King. I also do the same with my Xtol-R/XT-3R developers, helps to keep all the junk from going back into the developer I'm going to be using over and over again. Just my style of course, but it seems to work just fine for me, so I ain't changing a thing.

 

[Augustus Caesar]

That's certainly your experience, but I don't think you can generalize from that.

I have both done prewashing and not done prewashing and have never had an air bell. I always tap after every agitation, but I am using Nikor tanks and reels.

This suggests that the variable here isn't likely the prewash (or not) but either our tapping techniques or the tank/reels themselves.

This sort of makes sense to me. In my explorations of long development times/log agitation times, I found that plastic reels (or any other film support with plastic ridged walls) tend to trap liquid and/or not flow cleanly. With low agitation, this expressed itself as bromide drag. It might also be the source of air bells, I dunno.

I do "tap" or "rap" pretty aggressively after every agitation, though, so as to dislodge any air trapped along the film surfaces, so that could also be why I've not seen the problem.

In any case, I am not convinced that prewashing prevents air bells, but I don't discount that's a possibility when using the Patterson system.

In any case, I am inclined to believe Ilford. They know a bit about film processing


BTW, we've been here before:

Is there any possible harm to pre-wash before developing?

I just developed first ever roll of Tmax and, of course, it came out with the typical pink... unless steps are taken to correct, like pre-wash, longer fix, longer rinse, I learn. I am familiar with pre-wash, as I have been working with Arista, and its sheds its green stuff that way. So...

www.photrio.com

They probably haven't done testing using the same conditions that most amateurs are working in. I also cannot conceive how pre-wetting could harm anything.

 

[Chuck_P]

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.

 

[chuckroast]

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.

For what I have been able to dig up:

• They initially recommended it a very long time ago and then reversed their position with a view that pre-washing could lead to uneven development.
• They very strongly and specifically recommended against it for C-41 processing.

Unfortunately, I cannot find primary sources for this, only web references to them.

I think the most important thing here isn't to prewash or not - it's to be *consistent* in what you do.

I have not been doing it for some time, but I may return to it just because I do a fair bit of long/low agitation development which tends to build up contrast. Prewashing tames that somewhat in my observation.

I don't worry about anti-halation dye removal because even if I don't prewash, I use either a running water stop bath or multiple water exchanges to stop development. Either one of them flush most all the dye away.

 

[John Wiegerink]

Prewashing tames that somewhat in my observation.

I don't worry about anti-halation dye removal because even if I don't prewash, I use either a running water stop bath or multiple water exchanges to stop development. Either one of them flush most all the dye away.

Yes, but if you are using a replenish system, your used developer goes back into your stock tank or jug. If no prewash is used, then your anti-halation junk and whatever else is in there goes back in that tank or jug. I just don't get excited as some folks here to see my developer turn pretty colors. Especially when it comes to Foma films.

 

[chuckroast]

Yes, but if you are using a replenish system, your used developer goes back into your stock tank or jug. If no prewash is used, then your anti-halation junk and whatever else is in there goes back in that tank or jug. I just don't get excited as some folks here to see my developer turn pretty colors. Especially when it comes to Foma films.

Point taken.

Since I pretty much never replenish, this had not occurred to me. Mixing my own D-23, Pyrocat-HD - and when the times comes - PMK, DK-50, D-76, and D-72, turns out to be so cheap so ask to not make replenishment worth it, at least not in the volumes I process (less than 200 8x10 equivalents per year).

 

[chuckroast]

What Kodak (didn't) say ...

I just checked in my 1940, 1943 edition of the Kodak Reference Handbook. The section entitled "Instructions for Practical Development" (p. 711 and ff) makes no references to prewashing and is quite specific about moving film directly into developer after loading the hanger, reel, or tank as appropriate.

So it's pretty clear that they were not recommending it at that time. This is an important era for photography because an awful lot of photographic work was been done during WWII.

 

[MattKing]

Almost all the Kodak documentation is more oriented to commercial development lines than it is to hobbyists.
However the hobbyist oriented documentation that does exist suggests a method that almost no one I know uses:
"Smoothly lower the loaded film reel into the developer solution in the tank, and attach the top to the tank. Turn on the lights. Firmly tap the tank on the top of the work surface to dislodge air bubbles. Provide initial agitation for 5 seconds, and then repeat the 5-second agitation at 30-second intervals for the remainder of the development time. (See the table below for agitation techniques for different types of tanks.) Drain the tank."
You can't really use a pre-wash if you are lowering film into the top of the developer filled tank, rather than taking advantage of the features of tanks that are designed for "daylght" use.

 

[chuckroast]

Almost all the Kodak documentation is more oriented to commercial development lines than it is to hobbyists.
However the hobbyist oriented documentation that does exist suggests a method that almost no one I know uses:
"Smoothly lower the loaded film reel into the developer solution in the tank, and attach the top to the tank. Turn on the lights. Firmly tap the tank on the top of the work surface to dislodge air bubbles. Provide initial agitation for 5 seconds, and then repeat the 5-second agitation at 30-second intervals for the remainder of the development time. (See the table below for agitation techniques for different types of tanks.) Drain the tank."
You can't really use a pre-wash if you are lowering film into the top of the developer filled tank, rather than taking advantage of the features of tanks that are designed for "daylght" use.

I wish to politely disagree.

I do a lot of tank development. The first contains developer, the last fixer. The middle one is a running water bath fed from the bottom of the tank and overflowing from the top. I routinely place film reels or hangers into the second tank first, to prewash, and then drop it into the developer tank. When complete, it goes back into tank #2, this time acting as a stop bath.

 

[RalphLambrecht]

Well, Ilford are wrong!

No, they are spot on, and by the way, this can be tested. Just apply a drop of water to the emulsion before development and see what happens. In the area, where the drop was, development will be reduced.

 

[MattKing]

I wish to politely disagree.

I do a lot of tank development. The first contains developer, the last fixer. The middle one is a running water bath fed from the bottom of the tank and overflowing from the top. I routinely place film reels or hangers into the second tank first, to prewash, and then drop it into the developer tank. When complete, it goes back into tank #2, this time acting as a stop bath.

Like I said, almost no one does it like this

 

[mshchem]

Pre-wash with fixer.

 

[RalphLambrecht]

Like I said, almost no one does it like this

I bet this works well with Tmax, washing out the antihalation layer.

 

[koraks]

It is my understanding that pre-wetting the film prevents air bells from forming by destroying the surface tension.

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