Is this replenishment scheme going to cause excess development strength?

[hwy17]

No. It can't. Self-replenishnment from working solution can't ever (even theoretically) cause excess developer strength.

It can't even bring the strength of your replenished working solution to the strength of the original working solution. Unless you are doing 100% replenishment (before somebody asks, yes, 99.95% would be fine as well), of course.

But, you are probably more concerned whether you are replenishing more than you should. The answer again is no. So, what you really are asking is whether you are "replenishing" more than what manufacturer thinks is an acceptable drift from proper developer strength for a home user where they can blame the user and not their false advertising for less than optimal results. To which, obviously, there is not a definitive answer.

The excess development strength concern came from two beliefs I held:

1. That replenishment was always done to with working strength solution.

2. That the developer included in the kit was the same flexicolor develeoper replenisher that requires being aged with a starter or it can be too strong at regular fresh working strength.

I am still not totally clear about what the correct answer to number 1 is. With commercial volume combination developer replenisher solutions, how does the replenisher mix ratio actually compare to the starting working strength ratio?

 

[koraks]

With commercial volume combination developer replenisher solutions, how does the replenisher mix ratio actually compare to the starting working strength ratio?

For e.g. Fuji, you could find numbers like these:

Look at the bottom row of the table where it says "TANK from REP". This means "mixing a working strength developer as used in a tank or machine from an already mixed replenisher". As you can see, they take 850ml of replenisher, add 135ml of water and 15ml of starter. The starter is a solution of mostly sodium bromide in water. So you can take from this that a regular working strength developer is the replenisher watered down by around 20% and has some bromide added to it. You can easily conclude from this that the working strength developer is significantly less active (it's more dilute and the bromide further restrains it) than the replenisher.

Hope this finally clears it up.

 

[hwy17]

For e.g. Fuji, you could find numbers like these:

View attachment 401306
Look at the bottom row of the table where it says "TANK from REP". This means "mixing a working strength developer as used in a tank or machine from an already mixed replenisher". As you can see, they take 850ml of replenisher, add 135ml of water and 15ml of starter. The starter is a solution of mostly sodium bromide in water. So you can take from this that a regular working strength developer is the replenisher watered down by around 20% and has some bromide added to it. You can easily conclude from this that the working strength developer is significantly less active (it's more dilute and the bromide further restrains it) than the replenisher.

Hope this finally clears it up.

Yes that's perfect thank you.

 

[MattKing]

If the product when purchased is already at the intended working activity level, rather than at the higher activity level of the more traditional replenishers, then using it to develop a roll of film will decrease its activity by a small amount. When you discard some of that used developer and then top the volume up to its original volume with developer at the initial activity level, the activity level of the resulting mixture will be slightly less than the original.
As you use the working strength mixture, its activity level will slowly decrease over time.
The progression (regression?) of the activity level change depends on how much film is developed, and how much developer is discarded and replaced ("replenished") for each roll of film.
Increase the replenishment rate, and you will slow the progression.
You may be content with the progression - i.e. your requirements may be well satisfied with any film that you develop over the entire life of a kit, despite the variability you encounter. Others might require less variability.
If I was paying someone to develop my film, I would require them to objectively confirm that the variability that results from proceeding this way was within acceptable small tolerances - using sensitometry (control strips and densitometer plots).
If I was doing this for myself, I'd probably be willing to gauge the results more informally, based on results, but I'm cognizant of the risks.
Without the objective data from more formal sensitometry, I'm not sure I would recommend continuing replenishment of an existing used working strength volume after a kit is finished and with the contents of a new kit. To be safer, it may make more sense to discard and start anew. It may be though that the progression would permit using one or more additional kits before the results become less acceptable to the user - perhaps with an ever increasing replenishment rate.