Anyone tried kodak e6 patent(US5948604)?

[Rudeofus]

Ok, I guess you're talking about Spur developers, Adotech, Silvermax etc. I don't know if anyone synthesising HQMS for personal use have been able to create effective substitutes for these developers. Other than these, is there anything from the distant or not so distant past in the public domain?

As you probably know, E-6 FD is one of the best B&W developers out there, that's why Kodak formulated it this way. Ron told me, that unlike HQ the oxidation product of HQMS doesn't have developer properties, and this causes HQMS to give better sharpness than HQ.

The only issue with E-6 FD is, that it is a very very powerful developer, which would develop your B&W film to normal contrast within less than a minute. The way to handle this is dilution: E-6 FD working solution diluted 1+9 makes a very decent B&W developer. I typically use it at 26°C for 10-12 minutes, and this gives me at least normally developed negatives. I like the development at 26°C, since at summer time not even my cold water always comes out colder than that.

Since I have - I believe - already mentioned this at least once, you can consider this a formula in the public domain :-D

 

[Raghu Kuvempunagar]

The Wheatcroft patent has been discussed here several times, and IIRC was initially brought up by PE.
Although it can be shown theoretically that the conversion does not take place, it can also be verified experimentally: prepare a batch of developer per the patent and a second batch, where the H2O2 is added to the sulfite in absence of HQ and the rest of the developer mixed. Run parallel sensitometric tests. Alternatively, the free HQ can be extracted with ethyl acetate and quantified.
Oxygen can be used and the reaction proceeds as expected, but again, it is pH dependent and produces hydroxide, so either a strong buffer system has to be used or pH correction has to be applied continuously. This still means the liberated Na+ has to be bound up as some salt, the acetate or borate being the least troublesome. I thought I can be clever and use SO2 gas to neutralize the NaOH back to sulfite but it cannot work in a batch process, and it becomes a frustrating juggling act to do it continuously.

It seemed too simple to be true. Thanks for sharing your experience and perspectives.

Since I have - I believe - already mentioned this at least once, you can consider this a formula in the public domain :-D