Streaking skies, 8x10 Jobo C-41 developing

<p>I've been developing 8x10 Kodak Portra 160 color negs with a 3005 expert drum, in a Jobo cpp2 processor with Lift. The processor is leveled (so that the <em>drum</em> is leveled with precision), the easyrollers are rolling super smoothly on the correct position (extension arms outward), the motor is rotating fine (I have replaced gears and done the recommended lubrication), the temperature control is working perfectly, as well as the pump, etc, etc, etc. I usually develop five 8x10 negs at a time, and for that I use 900 ml of chemistry, in each step of the c41process: Developer, Bleach, Wash, Fix, Wash, Stabilizer.<br>

For some time I've been having inconsistent development, that is not apparent to the eye when you look at the beautiful 8x10 negs (they look absolutely fantastic!) But when I scan them, streaking appears, visible especially in the areas of sky. The streaking is not an unwelcome addition of the scanner: I do "work scans" at home, but also have had pro scans done for me, and the streaks for a single neg scanned both ways have been exactly the same, so they exist in the negative, regardless where the eye perceives them or not. <br>

I can only think of two causes for my problem at this point: 1) The anti-vellum which is somehow disturbing the first step of the process, 2) The unavoidable time required between step 1 and step 2 of the process, <em>AT LEAST</em> 30 seconds during which the tank is emptied of the developer, and refilled with bleach.<br>

1) Can I possibly improve this by pre-washing my film, as I've seen suggested in some posts? if that's the case am I losing/risking anything by doing it?<br>

2) Intuitively I find 30 seconds quite a longish time, relatively speaking, considering that developing time for the c41 process is only 3:15. My worry is what's going on in the emulsions during those extra 30 seconds before the bleach kicks in. But if this is a problem, how can I do otherwise? It's the time it takes to drain the tank and fill it up again, sometimes 30 secs isn't even enough, and I don't want to extra-contaminate my bleach bath by ending the draining beforehand...<br>

Suggestions? Thoughts?</p>

<p>Can you see the streaks on the negs w/ a loupe or in a contact print? I am unable to understand why they are appearing in a scan, and are not visible w/ a loupe when looking at the negs on a light table, especially with an 8x10 neg?</p>

<p>Jobo recommends, correction, requires a pre wash for their 2500 series tanks and the 3000 series most likely require it also. Check the usage instruction sheet that came with the tank.</p>

<p>If the problem is being caused by slow drain/fill times the density difference would be greater and not cause a streak unless the tank was stationary during the drain/fill and the streak would be consistent with the position of the tank and the negatives at the time of the drain fill.</p>

<p>There can be unevenness in the sky due to smog and haze also. The film, processing, and scanning will pickup small differences that are not apparent to the eye.</p>

<p>Steve: I was unable to understand it myself. The streaks on the negs are really subtle, almost invisible with or without loupe. The thing is, the scan does pick them up (and you can't see them at first, but you can when you darken and contrast the image via photoshop). The prints, however, eventually show them even when I am doing a normal print, not an exaggerated & saturated one. I only use extreme photoshop effects for detective purposes. But I print as close as the original, or my memory of the original, in natural tones. And the streaks re-surface. If I were taking pics with a 35mm camera, or with a handheld medium format rangefinder perhaps I wouldn't bother about this subtlety. But these being prints made from 8x10 negs, the imperfection really detracts from (if it does not plainly ruin) them.<br /> Charles: Jobo requires pre-wash only for black & white process. For c41 it requires only to "pre-warm" the tank or drum during 5 minutes, that is, to attach it to the processor and let it bathe and roll (empty) at the required temperature (38ºC). <a href="http://www.jobo.com/jobo_service_analog/us_analog/instructions/instructions_process_c-41.htm">see link</a>. But in some posts I have read at photo.net forums and elsewhere, some people recommend pre-washing for c41. Others are against. Can anyone comment on this?<br /> "If the problem is being caused by slow drain/fill times the density difference would be greater and not cause a streak unless the tank was stationary during the drain/fill and the streak would be consistent with the position of the tank and the negatives at the time of the drain fill."<br /> Sounds reasonable. A minor observation: the drum actually IS stationary while it is draining, whereas it rotates during the fill (when it reconnects to the rotating gear). The streaks have an inclination, and the tank during drain has an inclination.</p>

<p>Hmm... In silence there is eloquence... Did I scare someone with my lengthy posts? Was I too specific? Are there any experienced large format photographers developing with Jobo left??? Help!</p>

<p>Hi Jose<br>

Your not alone! I have the same problem with 4x5 drum processed with a JOBO. Still not cured the problem but have a hunch it may be connected with the Stabilizer. My process is the same as yours other than I always prewash.<br>

Next time I process I will dry and scan before stabilizing. Apparently stabilization can be carried out several days later. The streaks in the sky are always from top to bottom - which is how I hang my film to dry. I had been using a Photoflo bath after stabilization and thought that may be having a detrimental affect.<br>

<img src="http://i1173.photobucket.com/albums/r599/sabreglobe/C41JOBOprocessStreaks_zpscf911155.jpg" alt="C41 JOBO process streaks photo C41JOBOprocessStreaks_zpscf911155.jpg" border="0" /></p>

<p>Almost definitely a lack of pre-wash is causing the issue. If you have any water at all in your system before the developer goes in then you are inhibiting the initial reaction of the dev. Once I started using a pre-wash it fixed all my streaky problems with C41 (I use 2500, 3010 and 3005). <br /> From what I gather you need to pre-wash for quite a while too - I do 5 minutes to be on the safe side (but I'm using an automated ATL2500)</p>

<p>p.s. if you think it's drying then change the way you dry and see if the streaks change... What direction are your's in?</p>

<p>Thanks a lot, guys!<br /> <br />Brian, that's exactly the kind of effect I suffer, but in my case way more subtle since I started going obsessive in each possible step where things could go wrong. I am not sure about the stabilizer as a cause. In my case, I hang from one corner, and I have just verified that the streaks direction is not related to the way the film is positioned when drying, sometimes it's exactly the opposite... Looking at the skies, my streaks are mostly top to bottom of the image, same as yours, which is the direction of the rotation of the tank. Do you use a 3010 drum for your 4x5's? In that case, the film in the tank is positioned vertically, the same as my 8x10's in the 3005 drum. I tend to think the cause lies in development, as Tim suggests.</p>

<p>Tim, do you think, then, that the initial reaction of the developer is inhibited by having films wet upfront? Does the resultant "delay" make development more uniform? Could be. I wonder why Jobo does not suggest doing this, as they do for black and white (if you look at the link in my reply to Charles you can see that Jobo only suggests <strong><em>pre-warming</em></strong>) Do you have any intuitive explanation for what goes on, that is what makes developing more uniform? I'll try pre-washing in any case and see if there are differences.<br /> <br />Brian, I think Tim's p.s. is spot on. Try drying the film vertically to see if the streaks change. And thanks a lot for sharing your pic, I cannot explain how relieved I was to see those painful streaks: I've been going literally nuts for weeks! Still don't know if the solution is imminent, but at least I know someone has been having the same problems...</p>

<p> </p>

<p>I am using a Jobo CPE 2 processor with 2500 drum - not the expert type.<br />I use a fish tank pump to circulate the water to ensure even temperature throughout the tank and the Iphone 'iCelsius thermometer to accurately check the water temp. Poring in and out of the bottles is manual but quick so I think we can eliminate that one as a cause. <br>

I do pre-wash but sometimes this may only be for a couple of minutes. <br>

Certainly what Tim is saying makes sense. I will be a more scientific about the prewash stage and ensure a minimum of 5 minutes. Let you know the results if I get a chance to process this weekend.</p>

<p>. </p>

<p>Brian, please tell me about those results next time you develop. I myself will be developing a new batch of 5 8x10 negatives this week. I will pre-wash for 5 minutes this time, and will post about the results.</p>

<p>Hi Jose : Yes, development is inhibited by wettting and hence this ensures that the initial 'dump' of developer has time to wash across the whole film before penetrating. More importantly, if you have any moisture in the film already from any source, it negates any unevenness. <br>

I'm sure if your film is absolutely dry and the developer hits quickly there shouldn't be any issues. In reality you carry a big risk hoping for this which is ameliorated by pre-wetting. </p>

<p>Tim: Thanks for the reply, and for your clarity. I've been developing for some weeks now, always pre-wetting, and apparently things are going well. I still have to confirm this via a few scans that I'll do later in the day. Tomorrow I'll post my findings.</p>

<p>Problem is apparently solved! Thanks to all. To definitely confirm this I will have to have some pro-scans made, but the home-scans don't show any streaks as before. To anyone else out there developing C-41 in a Jobo Expert Drum and a Jobo processor here is my advice: Pre-wash!</p>

<p>Hi All,</p>

<p>Humm, Jobo's instructions are "Pre warm" for 5 minutes "DRY" not wet. <br>

Regards </p>

<p>Rob</p>

 

<p>Rob: Yes, I wrote about that on May 06. But Jobo seems to be wrong. Tim provides a sensible explanation. Better to wet everything beforehand evenly and to moderate the initial action of the developer. Also: "More importantly, if you have any moisture in the film already from any source, it negates any unevenness." I found that the expert drum's lid, for example, takes some time to dry in its inside. Also, if you've used the processor that day or the day before, the tube through which the tank receives the chemicals holds some water from the washing of the last batch.</p>

<p>Hi Jos,<br /><br />Yes Jobo drums are a pain to dry. I put mine out in the sun on a towel to dry ( I have extra drums so I can rotate drums ).<br /><br />Re “Pre warming”. C41 is a multi layered film which uses a controlled temperature specific diffusion process to develop the different coluors in the correct order. Pre wetting the film is likely to upset the diffusion rates. Do a search on this; there is good information from industry qualified people available at APUG I think. <br /><br />Regards<br /><br />Rob<br /><br /></p>

<p>Thanks for that Rob. I searched and found this thread in apug: <a href="http://www.apug.org/forums/forum40/103961-forgot-prewash-c41-problem.html">link</a><br>

It isn't a debate that is completely settled. What I do know is that my negs are looking better now, and will require less photoshop. Perhaps the ambiguity of the argument for or against can be summarized in these two messages posted by the same guy some months apart in the apug conversation mentioned above.</p>

<p>First message, April 2012: "Prewash may lead to problems in mismatched curves (crossover) due to uneven temperature, and streaking due to uneven development. It is only going to reveal itself when you scan or print the negatives." PE</p>

<p>Second message, November 2012: "Someone pointed this out to me. I have been unclear here.<br /> An improper prewet may lead to streaks and crossover, but a properly done prewet that evenly swells and tempers the film will not hurt, but rather it will help film. It leads to more even development and it reduces the chance of airbells (airbubbles or pinholes). However, it does dilute the developer more than a process done without a prewet." PE</p>

<p>Back to Tim Parkin on May 21 within this thread: "I'm sure if your film is absolutely dry and the developer hits quickly there shouldn't be any issues. In reality you carry a big risk hoping for this which is ameliorated by pre-wetting."</p>

<p>For me, it now looks like the Jobo process is FAR from perfect. And that it has been/will be a question of weighing a big risk (the one mentioned by Tim) against a smaller risk (the one mentioned by Rob). The negs I have scanned do look much better now. So whatever was being done at first following Jobo instructions strictly, it has been improved now by pre-washing, against Jobo instructions. The "mismatched curves" mentioned in the apug post or the "upset of the diffusion rates" mentioned by Rob don't seem to be as relevant (if they exist) as the impossible streaks I had when I did not pre-wash. Of course, I am saying all this comparing my negs then to my negs now. This is what has worked for me.</p>

<p> </p>

<p>Hi Jos.<br>

First, I am glad that your negs. looking better.<br>

Yes "link" that's the sort of information from P.E.</p>

<p>I am not aware of any film roller transport systems that pre wet before dev. I shudder to think of the millions of miles of film that has been developed in roller transport machines world wide.<br>

You can stick with what is working knowing that "dry pre dev warming" is there in the background, if you have problems. You could use a "Macbeth ColorChart Checker" to check that you getting the full range of contrast and colour ( we should all probably do this more often ).</p>

<p>Regards</p>

<p>Rob</p>

<p> </p>

<p>I can confirm the pre-wash also. I use 2 minutes. Also, check the dilution strength of the stabiliser.</p>

<p>I'm afraid still getting the streaky skys with 40 mins per wash :-( <br />Will try the lower temperature and longer development recommended by Tetenal.</p>

<p>I also had this problem on 4x5" Portra and solved it, not by pre-washing (which I also tried) but by using the 'alternative process' described in the Tetenal Rapid C41 instructions of developing longer at lower temperatures. This makes perfect sense.<br>

If you develop at the alternative of 8:00 minutes at 30 degrees C instead of the standard 3:15 at 38 degrees C, it is not necessary to quickly immerse the film completely and evenly. On 8 minutes, it doesn't matter much if filling and draining takes 10 seconds or 30 seconds, but with 3:15 at 38 that's critical. I pre-warm dry, 5 minutes.<br>

Developing for 8 mins at 30 gently immerses the film and gently starts the developing process. No streaks.</p>

<p>Thanks for the advice Gerard. Good results at last over the weekend - I was about to give up. It seams that for me the alternative process - 8 minutes at 30 degrees is the way to go. Pre washing made little to no difference. <br>

For the record my setup is the same as Tims shown on Youtube:-<br /><a href="

Now I am producing clean negatives I can shift attention to obtaining a better scan. I highly recommend "The Illustrated Guide to Film Scanning" for anyone using a V700/V750 or other DIY scanning setup. <a id="yui_3_7_3_3_1369393645206_1412" href="http://amzn.com/1484137434" rel="nofollow" target="_blank">amzn.com/1484137434</a></p>

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