mixing half kodak D-76

BetterSense said:

whereas my "in practice it works fine" theory is based on actual experience.

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... of relatively short term and small value relative to PE's decades of professional knowledge and much greater actual experience, combined with his understanding of both theory and manufacturing processes. You have missed the point that your extrapolation is unwarranted based on the limits of your experience and knowledge relative to that of PE and others. This isn't personal, it's just a simple fact.

Lee

Here's what I'm wondering about. A pack of Dektol is $6.50-$7.00 or so. If you don't use it up in six months - so what? That's a dollar a month, nothing compared to your film and paper cost, or even your time.
If you store the mixed chemistry in solution correctly, in a dark cool place.

- Thomas

Thomas Bertilsson said:

Here's what I'm wondering about. A pack of Dektol is $6.50-$7.00 or so. If you don't use it up in six months - so what? That's a dollar a month, nothing compared to your film and paper cost, or even your time.
If you store the mixed chemistry in solution correctly, in a dark cool place.

- Thomas

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That's very true. I think that their is something in photographer's genes that makes most of us tightwads - other than expensive equipment, of course.

I think of my sister and the dishwasher. She's a bit - no, more than that - unable to think for herself. She has told me that I can't put the dishes in dirty and get them clean. Of course, I put them in dirty and they come out clean. It's obvious who is right.

Just as a test on the "dishwasher" theory of yours Paul, I have seen dirty dishes placed in a dishwasher and have then seen it clog up due to the dirt particles clogging the screen. So you see that there is a basis to her thinking. It just depends on "how dirty is dirty", and here we are talking about "how well mixed is well mixed".

BTW, the clog happened in our home, with our dishwasher and with one of our daughters who put some plates with chunks of odds and ends into the dishwasher when mom and dad were out. We pre-rinse our dishes before placing them in the dishwasher to get food bits off. Larger pieces go into the trash. I believe that the offending dish was lasagna where some small pieces of the pasta was left sticking to the plates of the 3 kids that she was washing up after. And, she just didn't want to scrape the stuff off, just as you don't want to mix a developer all at once.

PE

I DO wash off or scrape off the big pieces!

Might not the special case of well mixed up D-76 powder in a sealed glass jar be granted an indulgence by Kodak?It's hard to see why the life should be significantly different from that of an unopened pack.There is very little oxygen,I did not do the calculation.

This question comes up all the time and the answer is always the same:

No, but why bother in the first place? What is D-76, maybe $4-5? Not worth ruining a roll of film or a few sheets to find out. Plus you need to store the mixed stock solution and the powder and keep track of both so I don't think there is any real economy to be reaped by dividing the powder.

If you use small amounts or use developer infrequently then:

• Settle on a long lasting liquid like HC110 or Rodinal. Or,
• Use an inexpensive powder developer and simply change out the stock every even numbered month, or every quarter year, etc. Plan on $12-16 per year for film developer and don't worry.

jeroldharter said:

If you use small amounts or use developer infrequently then:

• Settle on a long lasting liquid like HC110 or Rodinal. Or,
• Use an inexpensive powder developer and simply change out the stock every even numbered month, or every quarter year, etc. Plan on $12-16 per year for film developer and don't worry.

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Option 3: Mix it yourself from raw chemicals, most of which last for ages before starting to go bad. (I'm guessing that pre-mixed but unsealed D-76 goes bad because the ingredients react with each other.) The formula for D-76 has five ingredients, including water, so it's not difficult to mix. Some are even simpler; D-23 is three ingredients, including water; and PC-TEA's stock is also three ingredients, but the stock is made without water, so it becomes four ingredients in its working strength version.

Well, the argument of going bad once opened is this:

1. Surface area of these particles is very great and can trap a lot of oxygen and moisture.

2. Part of the barrier in the particles is Sodium Sulfite which protects the developing agents and is an essential ingredient in D-76.

3. The particles are alkali and sulfite/HQ/Metol and if the two particles lose their protective coatings, then the developer is considered mixed from a chemical standpoint.

4. The coating is a barrier layer similar to timed release medications except the time is zero so that it releases on contact with water.

5. Everyone out there is a chemist, has seen this stuff made and knows better than guys who have watched it made or had talks on the subject and so I can't convince you that it may work or may not, and so I offer the only foolproof alternative. And my friends from EK tell me I'm an idiot for trying to help you all and tell me to stop bashing my head against the wall for nothing.

6. IDK if Kodak still makes it but there was a 1 quart pack of D-76.

7. Remember the example of XTOL where the packaging was not quite up to snuff and the stuff was going bad before you could use it. In fact, it was even in 2 bags and still went bad!

PE

Photo Engineer said:

5. Everyone out there is a chemist, has seen this stuff made and knows better than guys who have watched it made or had talks on the subject and so I can't convince you that it may work or may not, and so I offer the only foolproof alternative. And my friends from EK tell me I'm an idiot for trying to help you all and tell me to stop bashing my head against the wall for nothing.

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There are likely many more people than you'll ever hear from who are smart enough to follow your advice, but just don't post their thanks or acknowledgement.

Part of my reason for posting in this thread is the hope that you'll stick around and not be driven off by people who contradict you with speculation as proof. APUG has lost too many people that I've learned the most from over the years because they gave up in the face of uninformed contrariness.

If amateur speculation becomes "accepted internet wisdom" we all lose.

APUG could use a good FAQ on mixing partial bags of powdered chemical mixes (along with a number of other topics) instead of these recurring threads that repeat the same old, drawn out debates.

Lee

Lee;

Thanks! The other day, someone here said I sounded like a broken record, and someone on another forum called me "cranky". Is it any wonder?

PE

I seem to be in a minority of one on this topic but I actually did this.

Well, not quite. I have, over the years, weighed out single-use portions of Microdol-X, D-76, Dektol, Acufine and others (along with their respective replenishers). Three things are necessary for this to be practical: dryness, a decent scale, and hermetically sealed bottles. I still have a couple of bottles that were packed over thirty years ago; I should try one of them and see if it still works. I have to admit having only 0.45 century of experience, but then I am an experimental physicist by trade, and one of our mantras is "If it happens, it must be possible".

With so many good liquid-form developers out there, I wouldn't advise anyone to break down manufacturer's packages of dry formulations, but the some of the same chemistry that allows glycol-based mixes to keep so well (lack of ionization of the ingredients due to the absence of water) does seem to apply to sufficiently dry powders.

Grey;

Actually, glycol based concentrates do degrade due to ionisation just like others. The best ones use TEA however, and gaseous ingredients such as HBr and SO2 gas introduced into the anhydrous TEA. This cannot be done with glycol based concentrates, nor can it be done in the home lab.

Another observation from one who has BTDT.

A word from the physicist side of me.... Cold Fusion!

PE

My favorite physics gag:

physicist #1: "So, what's new?"
physicist #2: "c/lambda"

BetterSense said:

My favorite physics gag:

physicist #1: "So, what's new?"
physicist #2: "c/lambda"

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I heard it as "Plancks constant" from #2.

PE

A bit of clarification.
I did not mean to dispute that the official recommendation of Kodak is the best way to go for regular users of D-76. P.E.,others,added interesting new information on this.
My point related only to the (small minority?) of users who keep a variety of long lasting developers mixed.For use of D-76 only every 2 years the sealed glass jar method worked for me so far.It is not fully tested and known reliable.
It saves keep buying new packs and throwing out most of it.

I do my Negs in batches - so I mix up Developer likewise

The stuff I don't use I Frisbee it there and then

For me then cost of a 5L pack of Developer is about the same as the Film in a single Dev Tank.

Having invested a considerable amount of time, effort and money in equipment to expose the film why risk messing it up saving a very few Dollars/Pounds/Euros ?

Life is too short to worry about such miniscule amounts of money

If you are concerned about the cost of your Photograph – go for Quality not Quantity when shooting

Martin

Martin Aislabie said:

.......... Having invested a considerable amount of time, effort and money in equipment to expose the film why risk messing it up saving a very few Dollars/Pounds/Euros ?

Life is too short to worry about such miniscule amounts of money

If you are concerned about the cost of your Photograph – go for Quality not Quantity when shooting

Martin

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My sentiments exactly.