- Joined
- Sep 14, 2003
- Messages
- 28
MWGraves said:I just souped 22 sheets of 5x7 HP5 in pyrocat with no problems at all. You aren't using an acid stop are you? That's a no-no.
erikg said:I was one of the folks who reported an issue in the previous threads. Sandy King has kindly offered to take a look into it, he has some test film that I processed and sent to him. In brief, I have seen the problem with 35mm and 120 HP-5+, but not with 4x5 and 8x10 sheets. It has occurred with and without presoaking, with and without acid stop baths, with and without distilled water, in small tanks and in a Jobo ATL processor. The previous threads cover a lot of the details and there is a scan as well. It seems to me to be an issue with some, maybe one batch? of recent HP-5+ and Pyrocat. Why? I hope we can find out.
I have looked carefully at the sample Erik sent me and the problem doesn ot appear to be pinholes. I am personally convinced that there is an emulsion defect of some kind in the film, because what you see is a very small light spot on the fim with a dark spot in the center, usually slightly oblong, in the center. Kind of like an inverse donut with an oblong rather than round hole. It is quite different from the shape you would expect from a pinhole caused by an eruption of the emulsion and not a phenomenon that could be explained by the developer. IMHO.
Sandy
I started that thread, and it seems the question remains open. Using same-batch HP5+, the result for me was exactly as Sandy describes it, and it appears independent of stop (acid or plain water) and presoak (none or 5 minutes). It's also independent of base (I tried the sodium carbonate variant, as well). It is not, however, independent of developer type. My tests with same-batch HP5+ in D76 produced no evidence of the problem. If it is due to an emulsion defect, it's a defect that is sensitive to PHD but not D76. I was very, very pleased with the results I was getting with this combination (HP5+ and PHD), and was sad to abandon it due these show stopping artifacts.
I have no idea why the pinholes. I looked at the samples that were sent me and they looked very much like separation of emulsion from the base, resulting in a kind of horseshoe look, varying slightly in size. I have actually seen this kind of look in my carbon printing when, during development the emulsion lifts from the support and breaks, falling back on itself. I suspect, but can not be sure, is that the cause in this case is the same.
When I repeated the tests with the film that Eric and Brad sent me I did not get any pinholes.
My suspicion is that the emulsion itself is releasing some gases, that in combination with the specific conditions of development, cause bubbles which then break. I looked on the Ilford forum and saw several other related reports of this problem with other Ilford films and another developer.
Since this problem is clearly very rare, and is not limited to the specific combination of HP5+ and one of the Pyrocats, I don't look for an early solution. I think Brad concluded, based on the fact that he had the problem with HP5+ and Pyrocat, and not with D76, that the problem was developer related. That could be the case, but based on the fact that there is a large base of HP5+ and Pyrocat users who are not experiencing the problem, it seems to me more of a specific condition issue than an issue of film/developer.
Sandy
I wouldn't say very rare, since several folks on this forum have experienced it. Also, the problem I have with a "rare" problem is it invariably seems to bite precisely when you care the most, spoiling impossible-to-repeat negatives. And this defect is impossible to correct in a 35mm negative printed traditionally. The blemish is way too small to spot on the negative, and I know of no really satisfactory way to remove the resulting black spot from a traditional print. (I've had good luck removing clear dust-related spots on 4x5 negatives with black latex paint, but tried and gave up on using a similar approach with 35.)
Was this a batch related problem with HP5? Did anyone keep track of lot or batch numbers and dates to see if there is an emulsion issue involved, which can be related to a specific run of film? tim
Actually you can use acid stop just fine with pyro developers. I've been doing it for years with no problems.
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