Scientifically formulated developers

[lamda]

Ryuji Suzuki wrote on his silvergrain.org web site "[D-76] was probably the first developer to be formulated based on scientific data. Specifically, combination of 2g/L of metol and 5g/L of hydroquinone was found to maximize synergistic "superadditivity" effect near the pH of 8.5, with the films of the time.

Does anyone have any information on which developers were or were not based on scientific data. Or, since D-76 was created in 1926, is there a timeline for the creation of the various Kodak developers?

 

[rbarker]

Sounds like a remark made to generate "discussion". But, I suppose it depends on how one defines "scientific data". All the folks before that wer trying to make BBQ sauce?

 

[lamda]

Sounds like a remark made to generate "discussion". But, I suppose it depends on how one defines "scientific data". All the folks before that wer trying to make BBQ sauce?

I don't know what prior developer creations lacked in scientific data before D-76; I'd speculate that they had some knowledge of chemistry, but just tinkered with the formulas until the results satisfied their artistic senibilities. Indeed, I don't know what kind of data gathering a reputable developer manufacturer today would go through before releasing a new developer.

 

[avandesande]

I am not sure if 'scientifically developed' means much of anything.
Keeping properties and economics also play a part in industrial chemistry, so they may have cut corners in one way or another.

The only thing that really matters are the results you actually get from a developer.

 

[gainer]

I hate to disillusion anyone, but the true scientific method is trial and error. It is, however, a bit beyond tinkering. It starts with some theoretical construct which leads to tests of the theory. If the theory works, it is kept until it doesn't work. The theoretical construct may be simple or complex. The main purpose is to find things that do NOT work so everyone knows not to try them again. In other words, we should not try to prove theories, but to disprove them.

All theoretical systems at least as rich as arithmetic are either incomplete or eventually lead to self contradiction. This is not my idea, but Kurt Godel's Incompleteness Theorem, which has been proven.

 

[Gerald Koch]

I can mention one developer that was not developed using the scientific method and that is Harvey's 777. Everything in the formula is measured in multiples of 7. Suspicious, you bet.

 

[Gerald Koch]

It's true that there is some trial and error involved in formulating a good developer. But that does mean that there aren't certain parameters which limit the choice of chemicals and their amounts. For example, in a low pH Phenidone/hydroquinone film developer the ratio of Phenidone to hydroquinone should be somewhere around 1 to 25.

 

[Photo Engineer]

Factorial experiments and statistics are used to design developers. This is only undertaken after the organic chemists and physical chemists have made their input regarding suitble developing agents and combinations thereof. The redox potentials at different pH values are made to suggest starting pH values for developers.

When the experiments are run, the photographic engineers run tests with pictures, H&D curves and also measure the sharpness and grain of the pictures. The developer is kept as a pre-mix and mixed solution for testing at intervals for seasoning, capacity and lifetime.

It may take years to come up with a suitable formula.

Then it is tested again with a variety of other manufacturers films to determine if there are any comptibility issues.

PE

 

[gainer]

It's true that there is some trial and error involved in formulating a good developer. But that does mean that there aren't certain parameters which limit the choice of chemicals and their amounts. For example, in a low pH Phenidone/hydroquinone film developer the ratio of Phenidone to hydroquinone should be somewhere around 1 to 25.

But that is some limit on optimality for activity. A different optimum or range of optimality might prevail if capacity or longevity is the object. I found that a ratio much greater than 25 has a longer storage life and capacity. When the amount of phenidone is kept constant and the amount of hydroquinone is varied, a plateau is reached where activity remains practically constant, but capacity increases. The only alkali in this case was 10% sodium sulfite solution.

This result was reached from what may be considered scientific data in the form of a graph of activity vs concentration, but might not be found if one is looking only for maximum synergism.

 

[tim atherton]

I can mention one developer that was not developed using the scientific method and that is Harvey's 777. Everything in the formula is measured in multiples of 7. Suspicious, you bet.

presumably for the use of Masons or Scientologists or somesuch...?

 

[df cardwell]

I can mention one developer that was not developed using the scientific method and that is Harvey's 777. Everything in the formula is measured in multiples of 7. Suspicious, you bet.

That would be Germain's formula. I don't think 777 has ever been published, and Mr. Harvey was a little more sophisticated than you suggest.

I'm with Gainer. Science is the method, not the labcoat. Technology is the interesting part.

 

[Alan Johnson]

It's quite rare for data from old journals to be quoted on the net but at the end of the following is an example of the scientific method:
www.groups.google.com/group/rec.photo.darkroom/msg/ad128c7dd785032b
I dont think any commercial developer resulted from this;AH17 and 18 are similar to the pre existing Beutler and FX-1.

 

[Gerald Koch]

That would be Germain's formula. I don't think 777 has ever been published, and Mr. Harvey was a little more sophisticated than you suggest.

Why the name 777 then? People who have compared the Germain formula and 777 say they behave identically.

 

[Photo Engineer]

It's quite rare for data from old journals to be quoted on the net but at the end of the following is an example of the scientific method:
www.groups.google.com/group/rec.photo.darkroom/msg/ad128c7dd785032b
I dont think any commercial developer resulted from this;AH17 and 18 are similar to the pre existing Beutler and FX-1.

In this reference there is talk of edge effects of different developing agents, but the poster apparently does not know that edge effects are generated by the release of halide ion during development, and can be controlled by outside influences such as silver halide solvents and added bromide or iodide in the developer.

Clearly, the scientific approach has merit. But, you have to know what you are doing.

PE

 

[gainer]

Speaking of edge effects and the search for them, I have lately seen some very sharp edges with the bright edge, but the bright line disappears under strong magnification. I was reminded by this experience that the human eye has its own edge effect.

A little astray, but humorous: in the days of the first orbital flights a special camera was built for the Mercury astronauts to use. It would show what the earth looked like by UV. The lens was very costly, as was everything on board. Later they realized that the window of the capsule had about the same transmission characteristics as the Earth's atmosphere.

 

[Photo Engineer]

Patrick, we have had this discussion over this story before.

The actual windows in the Mercury capsules transmitted enough light that they had problems with the pictures and had to add a UV filter on later filights. I know about this because our department at the cape supplied the UV filter set. It was the same set as used at high altitudes with reconaissance films, and NASA was very upset because they were getting 'advice' and 'equipment' from the USAF.

I handed the filters to Gordon Cooper and Wally Schirra personally outside the vacuum test chamber at CCMTA while one (I forget which) was wearing his space suit and carrying his helmet. I also explained to them how to use them.

Red Williams, the man who made the camera was with us to explain how to attach it and what filter factors to use.

Our dept., MTOEP, was Missile Test Optics, Engineering and Photography.

Enough off topic stuff. Sorry.

PE

 

[gainer]

Now that is strange. Tests of transmission that I saw results of showed the window transmitted about the same as the earth's atmosphere. 4th magnitude stars were about as dim as they could see, and that is what we see from ground without visual aid. I computed and mapped star charts for the Mercury astronauts to use for emergency alignment at reentry and had to take into account the window's transmission characteristics. Of course, our atmosphere transmits enough UV to give sunburn and to be dangerous to the eyes, but does it not attenuate most of the UV?

Perhaps I misstated the purpose of the camera. It was probably supposed to allow UV pictures of the star field that we could not get from Earth's surface. In any event, it was a mistake to assume that more UV would be visible through the capsule window than through the Earth's atmosphere.