Type 55 is the one that gives a negative and a print at the same time. Am I to understand that after developing, I should submerse the negative in water + PhotoFlo?
Certainly not an expert here, but....when using 55p/n, I've usually put the negatives into a water bath to keep them wet until I can get them to a sulphite solution. I've never used photo-flo (although I see no reason not to) and I do wash them very well followed by a "hang-to-dry". The reason for the little tub of water is because I've usually been away from home when I've used the film and I can carry a bit of water in one of those snap-top Rubbermaid plastic containers that's about the same size as the negative.
After clearing in the sodium sulfite solution, rinse for a couple minutes and place in a hardening bath for several minutes, followed by a thorough wash as normal. The type 55 emulsion scratches easily. The hardening bath helps toughen up the emulsion.
just an FYI, that negative will not fit a regular 4x5 print file selvee. Print File makes a version for that negative, and some negative carriers are difficult to use because of the size difference.
Type 55/665 Archival Treatment
1. Rinse negatives
2.Fix negs 3-4 minutes-hardener is good here
3. Rinse
4. Optional step if desired:HCA w/1:20 selenium 2-3 minutes gives you N+1
5.Rinse
6.Wash thoroughly
7.Photo-flo with distilled water
8.Hang up to dry