Update: I think I am going to scrap the benzotriazole in my ECN-2 experimental formula. It really doesn't seem to do anything positive, and in some cases, even at very low concentrates, it seems to cause speed loss. Most of my Kodak stocks didn't seem to suffer much, but my Fuji Reala 500D seemed to be only about 64ASA with just 1.25mg/L BZT in the mix. I don't know if that was causing the film's speed problem (I have another thread here on that). But when I eliminated BZT and the pre-soak and their following rinses, and developed for a tad longer (3.5min), the Reala now seems to have a speed around 250ASA (that's an anecdotal, unscientific assessment). Acceptable if it is about 10 years old.
I wonder if high speed films like that have something in them that a pre-wash could wash out, that affects speed? The post-prebath rinses looked very yellow.
Otherwise, it would seem the BZT may have had an undue effect on this emulsion, and as it doesn't really do anything quantifiably good, I left it out and will do so in future. I guess it's time to see if I can get my hands on some AF-2000.
Meaning that one would want to be sure the pH of the prebath is 10. Makes sense as the prebath would soak into the emulsion and thereby change the pH of the developer - at least initially, right? And I am also thinking, therefore, that time in the prebath would matter due to the amount of prebath soaking into the gelatin.
Also, please note that the pH may be critical as the alkaline prewet can change the response of the film in the developer due to a pH effect.
The developer calls for a pH of 10.25 @ 25 C, so if the pH of the prebath is much different from that is probably going to affect development.
From some of the suggestions above and in the control charts, pH is going to affect color balance and I suppose possibly giving the green cast that is showing up. 2:00 in the pre-bath may well be more than enough to loosen the remjet. I don't think 10 sec as called for in the specs will be enough for sink processing but maybe between 0:30 and 1:00? Guess I'll sacrifice a couple of feet and see what works. Using my soak and wash process at 2:00 I have NO remjet anywhere on the film so that will be the benchmark I will start with.
If the pH of the prebath needed to be adjusted, what would you guys suggest? My pH meter shipped yesterday. Maybe it'll show up today.
Last edited by kb3lms; 04-20-2012 at 01:50 PM. Click to view previous post history.
I haven't bought a pH meter yet but will do this week. I had assumed that whatever the pH of the prebath, a good enough rinse afterwards would remove it so that its pH might not be critical. But it looked like a lot of yellow dye or something was being removed with the rinses.
I don't use prebath with C-41, I just warm the dry tank, and this seems to give better results. I have done plain water pre-soak with ECN-2 and I thought this to be an effective way to raise the tank temperature and mitigate temperature drop when the dev. goes in - especially as the official methodology calls for a short prebath. But yesterday was the first time I used a carbonate pre-bath. Honestly, removing the remjet at the end is not a big deal.
I don't know, and I doubt, that the prebath caused the speed loss, unless it washed away chemicals in the film that enhance speed. But developing without the prebath (and without BZT and with extra 30secs dev) did seem to produce a much better negative with the Reala 500D. I'll do some scans tonight.
The pH meter will be interesting - my pH strips place the developer closer to pH 11 than 10. I may cut back on carbonate and do another test, when I have an accurate meter. For what it's worth, I was getting the green cast without using a carbonate prebath.