Photo Engineer said:Ryuji, the details of mixing during making of emulsions is a subject off-limits to me for this discussion.
As for the mention of injecting silver though, I do use relatively high pressure with short times and high mixing rates. This is known in the literature and there have been patents and discussions about it.
You may be interested in the novel methodology suggested by Wey and Whiteley in their US patent. I'm sorry but I don't have the reference at hand. I'll post it later if I can find the number.
Your published approach is also from the same era and looks much like Kodak publication AJ-12 as I said in another post. You surely have more modern versions but I have not seen them, and I wouldn't think of commenting on them without trying them out.
I make my emulsions in 120 or 220 gram batches and divide them into 30 g portions for easy breakdown for finish and doctoring experiments. So, for 10 makes of even 120 grams, this is 30 experiments and for 220 gram makes that is 60 experiments.
PE
Photo Engineer said:Ryuji, I'm sure it is a fine emulsion, but very complex. There are simpler and better ways to do what you are doing that are much more modern. There are also much more complicated and better ways to do this as well. It depends on your final aim.
If you look at the figure posted on Bruce Kahn's web site, you may get an idea of how complex the plumbing and electronics can get for a modern making station. That figure of his of course, is for a dual jet emulsion. In reality there are many more addition stations than even you mention above and more than he depicts in the 'real world'. Several can be in action at one time.
I'm also surprised at some of the steps you leave out and the methodology of adding ripener. It will work, I'm sure, but again I would do it differently.
The pBr is really pI since Iodide is present, so wouldn't it be better to report pAg? And how do you control pAg or whatever you measure? If the pAg varies, it may be due to iodide or bromide depending on addition method and unintentional solution flow rate fluctuations. What is your reference electrode plated with? Or is it plated at all?
Be careful of placement of inlet orifices. Positioning errors can give different pAg values depending on inlet spacing and mixer rate as well as electrode type. This emulsion will probably be difficult to scale up or down due to mixing problems. Just as an offhand suggestion you may want to make a 2x batch or a 4x batch to see if it still works.
The use of Phthalated gelatin will reduce the maximum grain size attainable at any given temperature, IIRC, but then it has been quite a while since anyone used that at Kodak or Fuji. I think phthalated gelatin was abandoned before T-grain technology.
I'm surprised you are not doing UF washing by now.
I see no provision for acid or base adjustment during the make. Of course, using phthalated gelatin this is impossible to implement, and that is too bad, as it would improve the emulsion in all probability. This is one of the major advantages of UF washing and one of the major disadvantages of using PA gelatin. There is a way around it, but you didn't mention it, so I guess you don't want to use acid and base adjusts.
I am avoiding T-grains, as they look and act too modern. I'm working with K-Grain technology.
PE
Photo Engineer said:Ryuji, oxidized gelatin yes, PA gelatin not much at all. It prevents some operations that requre acid - base shifts during the make. If used, it is at low conversion levels to prevent acid - base shift related problems.
The measure of pX or pAg is not accurate enough for this type of work. Iodide is usually run in slaved to silver and bromide is run in control with proper control equipment and proper measuring devices with appropriate electrodes. Somtimes other methods are used to control halide addition.
If your emulsion is a T-grain, I hope it avoids all current patents for both making technology and aspect ratio. Both are patented.
Yes, I am aware of the work of Maskasky, Daubendiek, Marchetti, Perry, Wey and Whiteley to name a few. I simply cannot discuss it in detail.
And, if my work does not bother you then why the continuation of this thread? Why start it at all? Why pick at my work? I feel that you are doing good work - albeit complex, and have no issues with what you are doing. I simply have different goals than you do, and know a lot that I cannot disclose and so walk a knife edge in my discourse here and in the work I do in my own darkroom.
I could write several paragraphs on measurment of pAg and variants, and several on mixing, but these are really off-limits. I could do the same for addition methodology, again it is off limits. I could discourse for hours on mathematical modeling of pAg with different halides, another off limit subject. How about emulsion scaling models. I know a lot about that as well. All of this is off limits as far as I'm concerned.
As for techniques, yes there are better emulsions but I choose to pick simple ones. Yes, there are a lot of ways to sensitize, and I have done most of them here or at Kodak. My raw and sensitized emulsions do very well. Out of the can the AgBrI has a raw speed of ISO 25. After sulfur sensitization and spectral sensitization I will probably get a lot more, but lose some to antifogging / stabilization, and addition of acutance dyes for sharpness. I hope for ISO 25 but may get as high as 100. That is my hope. I hope to do it with simple emulsions with no fancy equipment and no long making or sensitization steps.
I commend you for your diligent and good work. I hope that people are interested in it and I hope you can avoid patent infringement. I'm sure that there will be people interested in your work. I hope that perhaps some people will be interested in my work as well.
My comments above regarding your T-grain make were intended to show merely that there are many possible ways to do the same thing. T-grains are made at all major manufacturers plants and each manufacturer uses different methodology. I did not intend those comments to be taken as negative in any way. After all, if it works, it works.
PE
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