Help me understand replenishment in BW film developer

I've never really used a developer/replenisher regime until recently, and I'm somewhat unclear on exactly what is happening to the developer as it ages. I keep reading posts from guys who are using film or paper developers that are months or even years old, as brown as Guinness, but that apparently continue to provide good results. I understand the principle that the replenisher will to some degree kick the activity level of the developer back up to the prior level. What isn't clear to me is why this even works if the developer is so oxidized that it has turned brown (to clarify, I'm taking about an MQ developer here, tho I hear glycin has better keeping properties).

So if the developer is generally oxidized as evidenced by the color, by what mechanism is replacing an ounce of old developer with replenisher keeping these old developers active?

Replenisher is usually a version of that developer that is minus the bromides and a few other things that accumilate in used developer, it gets added in certain amounts per roll to keep the activity up. The accumilating reaction products also have a tendency to buffer the brew and give smoother looking tones and/or grain. By my experience HC110 is one of those developers that benefit from this buffering action.

While a replenishment scheme can work when using small tanks (i.e. your ordinary SS tank or Paterson), it's really made for deep tank development. These tanks are filled with some 5 gallons or more to begin with. It's very costly to replace this amount of developer, especially when it's just a matter of keeping count and add the correct amount of replenisher for each roll of film developed.
These tanks were found on every newspaper lab, where anything between say 10 to 500 rolls of film was developed daily. In the mid to late -80'ies C41 machines started to replace these units at some places as color printing equipment became better and cheaper. Then came the digi.revolution... Today there are very few places where such a deep tank developing scheme is viable. Almost noone does deep tank processing anymore.
Back to the question though. Back in the late -80'ies I used TMax developer/replenisher (which is the same soup) with good results, but gave it up because I didn't have the continuous throughput which I felt was neccessary for keeping my single gallon (5 liters that is) of developer alive. I sometimes didn't develop anything in 6 months. But please note that the developer was still fine when I tested it after these long brakes!

//Björn

A B&W replenisher is similar to the developer formula but may have somewhat more sulfite (or the same as the developer) and no or less bromide when compared to the developer formula. Its purpose is to maintain the volume of solution in the tank, maintain the sulfite level and the deveoper agent(s) level and bromide level.

The processing of film liberates bromide and iodide into solution and since the replenisher has no bromide it has the effect of lowering the concentration.

The best use of replenisher is when the tank "turns over" that is replenisher additions effectivly replace the tank volume of the developer within a month's time. Conventional practice holds that the tank should be replaced when replenisher volume equals the original volume(one turn over). Color systems are perpetual as long as turnover rate is sufficient.

In practice B&W has a lot of head room and I have extended the recommendations without problems both in 3.5 gallon hand tanks and roller transport machines.

With any replenishment system but especially one that has low through put some form of process monitoring with either control strips or test rolls is important to prevent unfortunate surprises.

Replenishment works exceedingly well even on a smaller scale, I currently use Xtol the 5 litre packs, this is the only developer that is self replenishing. So I use 2.5 litres as the stock - working solution and the othrer 2.5 litres as the replenisher.

At one time I used deep tanks, there were 3 of us using the same film processing darkroom and this was very economic. On a smaller scale I've used Microphen (ID-68), ID-11, Adox Borax MQ and finally Xtol they all worked very well. As I said in a post yesterday once ripened a replenished developer gives exceptionally good high quality negatives better than the same developer used fresh at FS.

Ian

Thanks, everyone. I'm pleased with the results I'm getting from this developer as it is being replenished (with a similar formula minus the bromide, as you say). I'm nowhere near having used a quantity of replenisher that equates the original volume. But based on what I'm reading, it appears that I can continue to use the developer even as it changes color toward yellow (and perhaps brown someday, who knows?) as long as I continue to use an active replenisher.

I'll write a longer post evaluating how this goes in a few months, when I can share my experiences with this developer. Thanks again.

Color is not a reliable indicator of developer activity. Just ask any Rodinal user. Also, IIRC, the original problem with XTOL did not show up as a color change. Some form of test strip is a good way to test the developer activity, especially before doing important work.

I've heard of people using replenished film developer as dark as coffee with no ill effects. As Gainer sez, color is not necessarilly a good indicator. For more than thirty years, I have used D23 replenished according to Eastman instructions with DK-25R. To be on the safe side, I replenish fewer times than recommended--about one half the number of rolls Eastman says is o.k. And as others say, once the soup has gotten a bit of "barrel age" it seems to produce the kind of smooth tonality I find very rewarding. I know there are folks who say that D23, among others, continues to oxidize once used; and they may be corect. By the same token, I have used the same liter of replenished D23 for months with no apparent ill effects. Plus, I like the idea of not pouring water and developer down the drain after each roll of film; so replenishment appeals to certain aspects of my character and personality. In other words, I am a also a cheapskate!

Ian Grant said:

Replenishment works exceedingly well even on a smaller scale, I currently use Xtol the 5 litre packs, this is the only developer that is self replenishing. So I use 2.5 litres as the stock - working solution and the othrer 2.5 litres as the replenisher.

Ian

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Perhaps for the developers sold as dry powders, but AFAIK so are the Kodak T-Max RS and Ilford DD developers.

I'll admit that Rodinal apart (which I first used probably 30 years ago when I took a bottle to Zaire as a Peace Corps volunteer), which admittedly can turn quite dark while remaining active, I had usually associated dark color = oxidation = the developer is expiring. I'll now set that notion aside, and motor on with my developer and replenisher even as they go yellow and so forth. Think I'll also try to pick up a can of aerosol gases that will "seal" the surface of the developer from oxygen in the atmosphere.

Trask said:

I'll admit that Rodinal apart (which I first used probably 30 years ago when I took a bottle to Zaire as a Peace Corps volunteer), which admittedly can turn quite dark while remaining active, I had usually associated dark color = oxidation = the developer is expiring. I'll now set that notion aside, and motor on with my developer and replenisher even as they go yellow and so forth. Think I'll also try to pick up a can of aerosol gases that will "seal" the surface of the developer from oxygen in the atmosphere.

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*****
The old lab rats who first taught me darkroom back in the early 1960s would breathe into the bottle before closing it up; contending it left a layer of C02 over the surface, that slowed oxidation. Mebbe so. If their "system" worked, I am willing to bet it was chewed cigar butt effluent that did the trick. I still do it, though, without the tobacco input.

Anscojohn said:

*****
The old lab rats who first taught me darkroom back in the early 1960s would breathe into the bottle before closing it up; contending it left a layer of C02 over the surface, that slowed oxidation. Mebbe so. If their "system" worked, I am willing to bet it was chewed cigar butt effluent that did the trick. I still do it, though, without the tobacco input.

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Total BS.

CO2 from the breath would simply dissolve into the water, and the amount in a few breathes would be insignificant anyway...

Kirk Keyes said:

Total BS.

CO2 from the breath would simply dissolve into the water, and the amount in a few breathes would be insignificant anyway...

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*******
Must have been the cigars, then! <vbg>

Ian Grant said:

Replenishment works exceedingly well even on a smaller scale, I currently use Xtol the 5 litre packs, this is the only developer that is self replenishing. So I use 2.5 litres as the stock - working solution and the othrer 2.5 litres as the replenisher.

At one time I used deep tanks, there were 3 of us using the same film processing darkroom and this was very economic. On a smaller scale I've used Microphen (ID-68), ID-11, Adox Borax MQ and finally Xtol they all worked very well. As I said in a post yesterday once ripened a replenished developer gives exceptionally good high quality negatives better than the same developer used fresh at FS.

Ian

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Just curious, what attributes do you see with replenished XTOL......grain, sharpness, smoothness, shadow/ highlights?