I recall a number of years ago when they found some photographs taken prior to World War I by baloonists trying to fly over the north pole (the film has remained frozen for 50 years), it was reported that the film was developed in a pyrocatechin developer. I can vouch for the fact that the new Pyrocat-HD developer generates virtually no base fog. You might consider it for a test. It uses a small amount of bromide to tame the fog generated by the addition of phenidone. The formula is on my site at UnblinkingEye.Com.(posted 8977 days ago)