How much replenisher vs total volume of developer?

[Alan9940]

I'm just starting to play around with replenished D-76 (new to me) developing 8x10 film with tanks & hangers. In Kodak pub J78, it says to replenish with 30ml (or 1 oz) for each 80 sq in of film, if any film other than TMax. I use both a 2-liter and a 5-liter tank, depending on how much film I've got to develop. The smaller tank will do 2 sheets of 8x10 while the larger will handle 6 sheets. Is the amount of replenisher used (30ml per 8x10 sheet) the same regardless of total volume of developer?

Thank you for your help.

 

[Paul Howell]

I believe it is. So 1 oz for every 4 sheets of film.

 

[MattKing]

Always remember that half of the replenisher equation consists of how much old developer is being discarded or removed through carryover.
The amount of byproduct laden old developer removed is important to how well the replenishment works. Because the byproducts are at least half the reason that you need to replenish in the first place.
The starting point recommendation means replacement of 30ml of old developer with 30 ml of replenisher for each 8"x10" of film.
That is why, past a certain minimum, the total volume of seasoned working solution is irrelevant to the question of how much replenisher is needed.

 

[mshchem]

When I was replenishing HC-110, I used an amber 1 gallon glass bottle, I scratched a "full" mark onto the neck. After developing 4x5 sheet film in open 1/2 gallon tanks I would add the required volume of replenisher to the glass bottle then fill back to the mark with the used developer from the 1/2 gallon tank, any extra used developer was dumped. Like most folks I didn't have any control strips or densitometer etc. Seems like every couple years I would mix up a new batch, mostly out of caution.

I should try replenishing again it's fun. I would need to get out and shoot film. Windchill today at noon was -29°C. Perfect!

 

[Alan9940]

Thank you all for the help.

In thinking about this question, it finally occurred to me that logically it makes sense that when the amount of replenisher used begins to approach the total volume of seasoned developer, then it's probably best to mix fresh and start over. After all, the formula for D-76R is certainly maintains characteristics of its D-76 brethren but it's not the same formula.

Anyway, I'm going to keep playing around with this replenisher idea and see how I get on with it. It may not become my "go to" development regimen but I will have learned something along the way.

 

[koraks]

it finally occurred to me that logically it makes sense that when the amount of replenisher used begins to approach the total volume of seasoned developer, then it's probably best to mix fresh and start over.

No, that's not necessarily the case and it certainly isn't how commercially run replenished systems work. In fact, those are generally only started over in case of major maintenance or severe technical problems. So it's common for such systems to have been 'turned over' many, many times.

Starting over can be necessary if the replenished system is for some reason not stable. I've read comments about some B&W developers apparently requiring a "hard reset" after a certain number of cycles, but this is not because there's something inherent to a replenishment system that makes it so. It's a signal of the replenisher formulation and/or rate just not being consistent with the actual depletion due to processed film and aging of the developer.

In such an uncontrolled system that requires a "hard reset" prematurely there's also no particular moment that's an obvious turning point at which the replenished solution needs to be discarded. So whether things get out of hand at about the single turnover point, or halfway there, or much further into the future, is basically an unknown.

 

[Paul Howell]

In thinking about this question, it finally occurred to me that logically it makes sense that when the amount of replenisher used begins to approach the total volume of seasoned developer, then it's probably best to mix fresh and start over. After all, the formula for D-76R is certainly maintains characteristics of its D-76 brethren but it's not the same formula

This is true, it is the reason that in the 60s and 70 replenished D76 had become sort of cult with landscape photographers. Russel Spearman was a commercial photographer in Sacramento in the 70s, but his passion was landscape, for B&W commercial/industrial work he shot 4X5 and 5X7 and used Polydol, for landscapes replenished D76, he had kept a tank going for years. I think I could tell the difference between D76 stock and replenished D76, not enough to make it worth my while to follow suite. I currently use replenished Acufine, on my second quart of replenisher, when that's gone I will dump the Acufine and switch to DK50.

 

[koraks]

After all, the formula for D-76R is certainly maintains characteristics of its D-76 brethren but it's not the same formula

The formula of a replenisher is supposed to be formulated such that the replenished developer will behave consistently. In the context of D76 and D76R, one would expect (ideally) that the replenished working volume will perform similarly or identically to a fresh D76 solution. That of course also means that the formulation of the replenisher D76R will most definitely have to be different from the original D76 formula. In general, you can expect replenisher formulas to be different from the starting solution in three ways:
1: More concentrated
2: Higher pH
3: Lower halide load
All of the above compensate for the actual usage of the developer, which tends to deplete the developing agent, reduce pH and increase halide load. Of course, the magic is in how to correctly formulate the replenisher such that it exactly balances out against the effects of developer use. Especially with B&W materials this is challenging due to the wide range of films that may be run through a replenished developer. It's also more challenging to keep the thing stable under conditions of infrequent and/or intermittent use.

 

[Paul Howell]

At least with replenished Acufine and DK50 I have not noticed any difference between rolls developed in fresh stock vs later replenished developer. With a densitometer I might find a difference in the characteristic curve. D76, maybe what I thought I saw was placebo effect. At the time I thought odd that he would use polydol for his bread and butter work.

 

[Alan9940]

Thanks for all the additional info...so much I need to learn about replenishing!

The D-76R formula I'm using definitely is a more concentrated solution vs standard D-76, but I'm a little confused by the substantial increase in Borax--20g in the D-76R vs 2g in D-76 (talking 1L stock volumes here.) I was never great at chemistry, but am I incorrect in thinking that this higher amount of Borax does not increase alkalinity? Isn't the addition of Borax to help stabilize the solution, especially with "so-so" water?

 

[Ian Grant]

The substantial increase in Borax just helps to keep the pH stable, it's a buffer with break down products from spent Metol etc.

Ian

 

[Paul Howell]

What is the capacity of replenished D76, I use old stock off the shelf Acufine Replenisher, the directions on the label on the can states that a quart of replenished Acufine is good for 64 rolls of 35mm X 36 exp. or 120 film, and by extrapolation 128 sheets of 4X5. Will a quart of D76 replenished develop 32 roll of 35mm?

 

[MattKing]

When it comes to replenishment, the differences between the more modern X-Tol and the historically prevalent D-76/ID-11 include the fact that X-Tol was designed to potentially never require that the working strength solution be discarded, while for D-76, the following applies:

 

[Paul Howell]

The folks I knew who were members of the D76R cult kept there tanks going for years at time, some replaced half of the working tank with fresh D76 every 6 months, while claim to never discard working D76R. Life of tank should be how long?