This is interesting. I was always under the impression the patent, while close, may not be the exact formula. So for example I assumed the listed formula for XTOL in Anchell/Troop was probably pretty close but not necessarily "it". I don't know much about patent filing, but if the patent is the formula, how is it there are still any proprietary developer formulas out there? What about the mysteries of HC-110? That formula is in Anchell/Troop too, and yet the conventional wisdom is the exact formula has never been disclosed. Another good example is Microdol-X. We know there was some kind of anti-silvering agent in there, but it is a trade secret. Why then, can't we just look up the patent?

I'm confused. Sorry this is off topic, but if we can look up patent filings, why hasn't someone made Ilford Cooltone yet?