fresh d76 vs 7mo old d76 vs d76 mixed up as needed just finished my tests

heespharm · Jun 25, 2010

So i ran a little experiment and i'll post the results later this week ... I had three groups...

1. d76 freshly mixed earlier in the week

2. d76 mixed on 12/01/2009 (7 months old stored in amber glass pharmaceutical bottles filled to the brim and sprayed with dust off and covered with saran wrapped and then capped and taped up)

3. d76 mixed by measuring out enough powder just to make 1 batch and mixed as needed (measured in electric scale and the portion of powder was calculated mathematically by taking the weight of the powder in the 3.8 liter bag and dividing it by 3.8 so I got grams of powder per liter...)

The negs are drying right now but i'll post examples probably tomorrow.... but i must say they look identical!!! I even forgot which roll was which until i remembered the subject matter each roll was shot..

Some other variables accounted for... same camera and same lens= bessa r3m with 40 1.4 nokton; same film = trix; same agitation = agitate for the first 30 seconds then 3 agitations every minute for 9.75 minutes at 20'C

so mixing a batch as needed can be done but i must say it was a lot of work... considering that I could mix up a big batch and store it in glass jars and still have it fresh after 7 months!!!...

i have 1 more bottle from the batch that was mixed on 12/1/2009 and plan to open it on 12/1/2010!!

Anon Ymous · Jun 25, 2010

heespharm said:
...so mixing a batch as needed can be done but i must say it was a lot of work...

Assuming that the negatives are indeed identical, there's still one problem with your scenario: Your statistical sample is too small. You tried it once and it worked; will it work nicely the second, third, ..., nth time you try it?

Neal · Jun 25, 2010

Dear heespharm,

I look forward to your results. A small question, but did you mix D76 from the Kodak package or from bulk chemicals?

TIA,

Neal Wydra

heespharm · Jun 25, 2010

Kodak chemicals...

Oh and I mix it as needed regularly... With similar results (a grade 2 printable neg)

Anscojohn · Jun 25, 2010

One think to keep in mind is that many of ye oldene lab ratz always insisted "Hit takesawhaal a usin' afor the 76 getz goooood."

Many of them, if not using deep tank replenished D76 would always add a dollop or two of used D76 to the small tank/reel before filling the tank with fresh d76.

The photochemists on board can say more about that, I am sure.

brucemuir · Jun 26, 2010

I'm interested as I use ALOT of D76.
I love the stuff even thought I use PMK and Rodinal and went through a Bottle of syrup HC110 when I was learning.
I use it 1+1 in a small inversion tank so can't speak to replenished use.

I once had some D76 that was over a year old and worked well but I don't have a densitometer.

Photo Engineer · Jun 26, 2010

D76 does indeed keep well, but not forever. It can give good results fresh too, but the results will change slightly over a 1 - 3 day span due to a tiny pH change. The big problem is that the powder in the bag is not uniform. It consists of at least 2 if not 3 individual encapsulated chemical packets that were prepared in an inert atmosphere using an encapsulating agent to prevent premature spoiling. If you take a small quantity, you may not always get a uniform mix of ingredients. It always fails with the "must have" photos. So, good luck to you.

PE

Tom Kershaw · Jun 26, 2010

PE,

I made up a 1000 ml batch of D-76 from scratch on June 8th and then after a few days processed a roll in the Jobo using 125 ml of stock solution; in the process creating more air space in the 500 ml brown glass storage bottle. Should I be able to expect similar performance from the stock solution within the next few days, that is, how long does D-76 stay stable for (assuming de-ionized or distilled water)?

John Sexton's article: http://www.largeformatphotography.info/articles/sexton-tmax.html from 1987 suggests that D-76 should always be used 'FRESH' - his emphasis, due to the formation of hydroquinone monosulphonate (increasing developer activity). As various D-76 derivatives have been proposed and used, including the hydroquinone free D-76H, how seriously concerned should one be, and are there disadvantages to using D-76H over the standard D-76 formula? I'd make a guess at lower capacity and longevity but I may well be wrong.

Tom

Photo Engineer · Jun 26, 2010

Tom;

The formation of HQMS decreases activity, but also causes a pH change. The net reaction is therefore rather neutral in overall result, but in the day or so after mixing, the change is up then down in activity. This is in both Haist and Mees and James, but I just searched Haist for my reference and could not find it. If I do, I'll post it, but for now I can't locate it.

Sorry.

PE

Photo Engineer · Jun 26, 2010

Tom, I found the best reference in Mees and James, p 289.

HQ + O2 + Na2SO3 -> HQMS(Na salt) + Na2SO4 + NaOH.

This causes lower activity due to the HQMS but higher activity due to NaOH. There is a slight imbalance as the dissolved oxygen is used up, and this continues every time the developer gets a shot of fresh oxygen. This takes place in every developer that contains HQ and Sulfite, unless the system is very very well buffered.

Hope this explains things to everyone.

PE

Tom Kershaw · Jun 26, 2010

Photo Engineer said:
Tom, I found the best reference in Mees and James, p 289.

HQ + O2 + Na2SO3 -> HQMS(Na salt) + Na2SO4 + NaOH.

This causes lower activity due to the HQMS but higher activity due to NaOH. There is a slight imbalance as the dissolved oxygen is used up, and this continues every time the developer gets a shot of fresh oxygen. This takes place in every developer that contains HQ and Sulfite, unless the system is very very well buffered.

Hope this explains things to everyone.

PE

- so is D-76H actually redundant from a functional perspective?

Tom

Photo Engineer · Jun 26, 2010

Tom Kershaw said:
- so is D-76H actually redundant from a functional perspective?

Tom

I could not say. You would have to test that for yourself, as I have never run that test.

Sorry.

PE

lajolla · Jun 30, 2010

as always, photo engineer is the maestro in regards to kodak chemicals and kodak chemistry.
one additional caveat for attempting to use freshly mixed d76 - the initial H2O solvent temp for mixing the powder is between 122 & 131 F - I have always let the fresh, hot developer cool down to ambient room temp before using, either full-strength, or diluted, with whatever initial fresh mixed solution volume. In various climates around the world, this cool down period is usually at least 24 hours.
I have found that forced cooling of freshly mixed d76 in order to use the developer solution within a short time of mixing is a recipe for disaster.

Nicholas Lindan · Jun 30, 2010

As I understand it the increase in D-76 activity from NaOH formation and pH elevation was well known to Kodak in the 20's. Several attempts were made to buffer the developer against pH changes and the recent Kodak product has almost no pH change over time. Richard Knoppow on the Pure Silver list has more information on the subject.

Some DIY D-76 formulations do exhibit pH increases over time. I think the most prone formulations are made with Kodalk/Metaborate.

The real knowledge of black and white development was/is in the motion picture side of the industry. The need to produce very consistent developing results - allowing shots made months apart to be spliced together without shifts in contrast or density - drove the effort to formulate very stable developers and very consistent film stocks.

Tom Kershaw · Jun 30, 2010

Nicholas Lindan said:
Some DIY D-76 formulations do exhibit pH increases over time. I think the most prone formulations are made with Kodalk/Metaborate.
.

I used Borax rather than Metaborate.

Tom

heespharm · Dec 14, 2010

So I just finished my year long experiment with d76... the batch I did today was mixed on 12/01/2009.. I got good useable negatives... if anything i saw negs that were too dense but keep in mind the roll was from a holga around noon with trix 400 so the negatives should have overexposed ... but still not so much that i couldn't get an image from it..

my technique was to mix the d76 and fill glass pharmaceutical grade bottles (I get them from work because I'm a pharmacist) fill them to almost the brim, spray compressed air around the mouth of the bottle and put plastic wrap over it.. then cap it, tape the cap around the joint of the cap with the bottle with duct tape

just to show it can be done to preserve d76 but far from optimal... the best thing to do is just mix fresh...

msa · Dec 14, 2010

Not sure why you'd keep it for a year, anyway...if you're a low volume/occasional D76 user, just use the liter packages.

I buy those in bulk, even though I go through a couple a week. Prefer to mix a couple of days before use, and not to store anything mixed very long.

heespharm · Dec 14, 2010

Oh it was some discussion that d76 cannot be kept bottled for longer than 3 months... I had 3 bottles that I said I would try it out on just to see for sure

msa · Dec 14, 2010

heespharm said:
Oh it was some discussion that d76 cannot be kept bottled for longer than 3 months... I had 3 bottles that I said I would try it out on just to see for sure

Oh, sure sure, I understand why you did the experiment and posted up about it.

I just don't understand why people try to use 3 year old (mixed) chemicals to save a couple of dollars, that's all.

Gerald C Koch · Dec 17, 2010

Tom Kershaw said:
- so is D-76H actually redundant from a functional perspective?

Tom[/QUOTE

At the low pH of D-76 the hydroquinone acts primarily to regenerate the Metol as the developer is used. It provides very little developer actiivity. Grant Haist therefore suggested eliminating the hydroquinone from the formula of D-76 when it is used as a one shot. To achieve the same activity the Metol was increased to 2.5 g/l.

ZoneIII · Jun 28, 2011

"my technique was to mix the d76 and fill glass pharmaceutical grade bottles (I get them from work because I'm a pharmacist) fill them to almost the brim, spray compressed air around the mouth of the bottle and put plastic wrap over it.."/QUOTE]

Just curious but why would you top the bottle off with compressed air. You would just be replacing air with air. The idea is to replace the air with an inert gas. Then again, I see you said you spray compressed air "around the mouth of the bottle." What does spraying air around the mouth of the bottle do?

heespharm · Jun 28, 2011

From the co2 spray cans... Co2 replaces oxygen... We do this in brewing beer too

Usagi · Jun 30, 2011

Gerald C Koch said:
Tom Kershaw said:

- so is D-76H actually redundant from a functional perspective?

Tom[/QUOTE

At the low pH of D-76 the hydroquinone acts primarily to regenerate the Metol as the developer is used. It provides very little developer actiivity. Grant Haist therefore suggested eliminating the hydroquinone from the formula of D-76 when it is used as a one shot. To achieve the same activity the Metol was increased to 2.5 g/l.

Click to expand...

Very interesting indeed.

As the most (I guess) will use D-76 as one shot developer, the D-76 without the hydroquinone would be best.

Just for curiosity, why hydroquinone was included to D-76 in the first place?

heespharm · Jun 30, 2011

So it can be replenished instead of d76 being one shot

fresh d76 vs 7mo old d76 vs d76 mixed up as needed just finished my tests

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