mixing half kodak D-76

[Kirk Keyes]

Yes, I agree. But I know from experience that you can do it, and it works, and I don't buy any of the arguments about the powders separating funny. This is photography, not rocket science.

I see your BetterSense is working fine.

[Photo Engineer]

Gunpowder used to be made as "mealed" which was simply a mixture of the 3 ingredients. After shipping in open carts or in burlap bags, they found that it burned unevenly due to the separation of the ingredients during the rough handling of the wagon trains that shipped it to the front.

Later, "corned" powder was invented in which the ingredients were mixed into an even paste and dried and then ground (with great danger) into "corns". This powder was much more dependable as it did not separate out during shipping.

Now, this might seem to be an argument in FAVOR of partial use of a developer package, but consider this.....

Some of the ingredients cannot be mixed together, but are rather "corned" in individual groups which are then mixed into one air-tight package. Therefore the different varieties of "corns" can become separated upon shipment into layers which are not easily redispersed evenly. In addition, they are now exposed to air and moisture.

So, the results at best are uneven and unpredictable.

Don't do it.

PE

[BetterSense]

One gets such wholesale returns of conjecture out of such a trifling investment of fact.

The irony is that the "never mix up half a batch or you will suffer total protonic reversal" theory is the conjecture, whereas my "in practice it works fine" theory is based on actual experience.

[Paul Verizzo]

As mentioned, this topic comes up every few months. And thus, APUG'ers fall into two camps. One, "Oh my gawd you can't do that because gravity will cease," (the theorists) and the pragmatic, empirical, results oriented. You can easily guess which side I'm on.

I wouldn't divide a powder packet, though, without serious mixing by food blender, paint mixer or something. And ya know what? That's exactly how Kodak made the stuff to start with. Mix a lot and portion out. That one liter packet of dry chems came from maybe hundreds of pounds. If you further divide it, you are only replicating how is was divvied up in the first place.

Another system that gets the theorists in a dither is freezing developers. It works (empirical). Just remove from the freezer a day before using so that the sulfite works its way back into the solution.

"Perfection is the enemy of good enough."

[Photo Engineer]

My experience is both from theory and practice Paul. The formulas are compounded more like cement in a large dry powder mixer which gives a constant gentle tumble to the blend so as not to break up the "capsules" which protect the various chemicals from coming into contact. It is also done under an inert atmosphere. Therefore there are two significant differences to your description. A food blender destroys the encapsulation and aerates the mix.

I see we have my advice and Kirk Keyes agreeing. We are both practicing chemists with nearly a half century of experience between us. The best I can say to you is do what works, but remember that this may work even 9 out of 10 times but may only work 1 out of 10. Chances are, you are going to have a "dud" developer in the near future. Have fun with it and I hope you don't ruin some valuable pictures. Please agree to take the responsibilty for your advice as well when people come knocking at your door.

The advice we give is foolproof advice.

PE

[Lee L]

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

... 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

[Thomas Bertilsson]

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

[Paul Verizzo]

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

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.

[Photo Engineer]

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

[Paul Verizzo]

I DO wash off or scrape off the big pieces!