Has someone used D-76 this way?

Hello,
Yesterday I mixed a gallon of Microphen and a gallon of D-76... The Microphen box indicates replenishing it with 50ml of Microphen stock for every developed roll... I put a liter of it apart in an amber glass bottle, for stock development that way... I never did it this way before, only 1+1, 1+2 or just reusing stock adding a bit of time to the last of the ten rolls per liter...
That made me remember once I read (maybe Ian Grant?) D-76 can be for some time replenished with D-76 instead of D-76R, but the system will collapse after some time if I remember well... So I put a liter of D-76 apart too, to try that for the first time: I can`t make the D-76R... I don't need the system to last for long...
Optimal -Kodak words- is the use of 240ml for each roll, so I plan to use that liter of D-76 for four rolls, but here's my question: how much stock D-76 should I add after developing each of the four rolls? I feel no adding it wouldn't be right...
And for how long would the system work?
With my tank I need 400ml for a 35mm roll and 600ml for a 120 roll, so this way I would't waste as much D-76 as if I simply discarded the stock solution after each developed roll...
Thanks!

If you want a self-replenishing developer that works like D-76, use Xtol. Stock times are usually the same, it's designed to self-replenish indefinitely, and you'll get better sharpness, same or better grain, and 1/3 stop additional film speed.

There's not going to be any data for using D-76 in self-replenishment, aside from anecdotal reports from people who've done it. That said, @Ian Grant is a member here; perhaps he'll chip in on whether it was him and if so what he knows.

Thanks, Donald... I'm sure -as you say- I'll end up using Xtol: I did it twice already, the last one replenishing it, but as I've generally preferred sharp grain, I never used Xtol as my main developer because it's too solvent even diluted... But now I'm interested in small negatives with solvent developers for a few personal photographs, so after this gallon of D-76 and after seeing what it does replenished with itself for a few weeks, I`ll get Xtol for dissolved grain from then on: I can`t imagine a better option in this specific case.

Ilford's ID-11 is functionally equivalent to D-76, but due to Kodak's ownership of a useful patent ID-11 comes in a two part package, while Kodak D-76 comes in a single package.
That turns out to be an advantage, because the two part package permits you to use ID-11 in a replenishment regime, by modifying how much of one of the packages you mix up. Ilford puts instructions about how to do that on their website, in a document about a replacement for their now discontinued purpose made ID-11 replenisher. Kodak used to make and sell D-76 replenisher too.
As I understand it, the difference between the basic developers and the purpose made replenishers was mainly in how the using the replenishers kept the development byproducts at bay.

Great info, Matt... Thank you!

Maybe Chemists can answer:
What I imagine is when one 35mm roll has "taken" some D-76 from a liter of stock solution for a common development, and the used developer goes back into the liter bottle to make nearly one liter again, some of its power and concentration has come down... And some of its byproducts control capacity too... Would you replace those loses with the optimal 240ml recommended by Kodak? If so, that would be done by adding those fresh 240ml before filling the liter bottle to the top with part of the just used developer... Not to make a long lasting replenishing system, but to develop just a few rolls for a few days...
It seems to me 240ml would be too much, but I'm no Chemist...

Ilford did a lot of work on Replenishment in the 1950s for their Phenidone based developer Autophen a PQ version of ID-11/D76 for commercial photo finishing labs, T hey measured how much of all the components chemicals were used to get more precise replenishment information. With a PQ developer you can replenish for afr longer than an MQ developer and in fact one labe replenished Autophen for several years. Autophen had two replenishers one for topping up relinishment the other for bleed replenishment. The difference is you are literally just topping up the working developer to maintain the same volume, with bleed development you are discarding working solution to allow for the needed volume of development.

You could ask why is this important. The answer is quite simple the developing action of Metol is suppressed as Bromide levels in a working solution increase so the more films processed the higher the Bromide level, while Phenidone can tolerate very significantly higher levels. So with an MQ replenished developer we need to remove more developer volume in order to help reduce the Bromide level as the replenisher contains none.

The actual Replenishers that were available for D76/ID-11 did contain extra Metol t& Hydroquinone to keep the level correct and Borax to stabilise the buffering, so the Ilford and Kodak systems of Replenishing with fresh stock are a compromise and not ideal. I've not really looked at tehm in detail if I used ID-11/D76 again I'd mix from raw chemistry and use a separate replenisher.

Juan, when I was in Chile and Peru a few years ago I saw D-76 and replenisher (and other items) in photo stores, made up and packaged locally as dry chemicals. Is there no-one near you who does anything similar. If you can get it I'd use Xtol, however I do remember trying to get Kodak Tmax films near impossible when I was there, Kodak's marketing in Chile/Peru was largely colour film, paper and chemistry to minilabs.

Ian

Thank you very very much, Ian... Great explanation!
My main present reason for trying this with D-76 is that Xtol is not sold around here, but I'll order a couple of bags with the rest of my next order from Freestyle, which could be in two months: last week I received film and chemicals and large trays, so I'll wait a little for the Xtol while playing with D-76. No doubt I'll use Xtol... Who knows if this is the last D-76 for me... Except for 1+3 with D-76 for sun and sharper grain, it's hard to find a reason for D-76 in front of Xtol...
I'm testing these days 2 or 3 35mm frames only, from several films, in D-76 stock in every development: that's why I wanted a decent way of using my D-76... I use 400ml of stock solution for that small amount of film, so I have to do something different than dumping pure D-76...
It's a shame we have basically no access to materials in these countries: we had at least a few of the best films, chemicals and papers available some years ago, but things got worse lately... Only in Buenos Aires (Argentina) there's a good store doing it decades ago, but apart from that, in all our countries even people who mixed chemicals or repackaged film, have stopped doing it... I buy from the USA and from Europe most of the time, depending on availability, and also depending on friends coming, fewer times...
And yes, as you say, no TMax line here! We've just got a couple of options: Ilford PAN400 in 35mm and (the same) HP5+ in MF; and FP4+ in 35mm and MF... Anyway both films are great... Kodak products are a lot more expensive for a local business, and at Kodak they ask our very few and small sellers to buy a lot more film than Ilford do... So there's no chance for the third world economy... Likewise, I can buy D-76 here, but no other Kodak developer...
After this last bag of D-76, Xtol from Freestyle will be it...
Thanks again!

Juan, I was shocked that Kodak had neglected the South American market and that was around 10 years ago, but very surprised how Foma had filled the gap alongside Ilford who'd always had a good presence. I had similar issue with Kodak products whlie living in Turkey.

Ian