Pyrocat-HD vs MC Vs. Rollo Pyro / ABC+ for use in Jobo [Archive]

Tim V

12-Mar-2019, 01:12

Hi all,

I asked this in another thread, but thought it best to start a new one to address the topic and keep the other one on track.

Anyway, I have a new CPP-3 landing soon and plan to use it, among other things, for processing 8x10" sheet film in a 3005 expert drum. Up until now I have been using PMK and processing one sheet at a time in trays. I have been very pleased with the result, but have read many times that PMK doesn't play so well with Jobo / rotary processing. From my reading here and elsewhere, it seems Pyrocat-HD is the most used pyro staining developer in this case, but I also see there is the option of the MC variant and Rollo Pyro / Photographer's Formulary's ABC+ Pyro (which I've read multiple times is based on PMK.)

My questions re. the above options are really as follows:

1: Which is the most reliable when using with a Jobo? (The differences between HD and MC seem greater film speed with the later, and perhaps shorter development times? ABC+ seems a bit more complicated with the prebath etc?)

2: Which will give me a stain that is similar to PMK, with close printing characteristics when using VC fibre papers?

3: Recommended developer solution per sheet with these developers seems to be a minimum of 250ml, and in a fully loaded 3005 drum this equates to 1250ml. I understand that this is pushing the limits of the motor and especially the load capacity of the lift. Would people recommend doing a one bath development with this much developer solution, or instead splitting the development time into two parts, each of equal time using 1000ml? (e.g. 5min with 1000ml, dumping, then another 5min with 1000ml.) I also wonder if 1000ml is simply not enough solution to immerse the sheets in the drum quickly, and might result in streaking etc?

4: My reading is that with all of these developers, it's best to use minimum rotation speed and to give at least a 5min presoak–filling and dumping the water several times. Sound good?

5: Lastly, I'm shooting mainly HP5+, so any specific times / tips for Jobo processing with these developer / film combinations appreciated!

Thanks for your time,

Tim

Pere Casals

12-Mar-2019, 04:54

Tim, you may find ample information here: https://unblinkingeye.com/Articles/PCat/pcat.html by Sandy. This is 1st quality information.

1) Any one containing an antioxydant, Ascorbic/Vit C , Pyrocat MC is better for rotary but HD can also work with slow rotation speed, or by sourcing Nitrogen (or other) in the drum, or replacing developer in the mid of the development.

2) In page 3, https://unblinkingeye.com/Articles/PCat/PCat3/pcat3.html it explains that depending on developer the stain may vary in color, so if using variable contrast paper then this has an effect in the contrast.
Brown vs Greener stain is what has a effect with VC, so take a developer with same stain color.

3) No streaking, I guess, development time into two parts IMHO is to source new fresh developer in the second bath to avoid developer oxydation effects in the "general stain", so stain of the fog+base.

4) Minimal rotation is always good, high speed rotation creates additional stain fog (general stain) with stain developers lacking an antioxidant.

Alan9940

12-Mar-2019, 08:21

Hi Tim,

1) I've used Pyrocat-HD in Expert Drums on my CPP-2 for 20+ years without issue. Use slowest rotation speed. I wouldn't recommend PMK, ABC, etc, for rotary processing.

2) if you want a stain similar to PMK, then you'll need to use one of the pyrogallol based formulas. Again, not recommended for rotary.

3) Can't remember the last time I ran a full drum of 8x10's, but I'm pretty sure I used 1L of developer and it was fine. Test to be sure.

4) I use a 5 min water pre-soak and don't dump/refill.

5) Don't use HP-5, but the Massive Dev Chart and other online resources will certainly provide a good starting point.

Jim Galli

12-Mar-2019, 08:27

Can only speak for myself. I started out with PMK pyro (bought the book and followed the religion) and never could solve the edge effects no matter how developed. It's like you had to trim a 3X4 neg out of your 4X5 to get rid of the edge density. I tried everything. Then I switched to Sandy King's PcatHD which is cheaper to make and never looked back. Cheaper, better, easier, almost fool proof (ask me how I know this). I mix it up with complete abandon from stuff I buy in bulk from sellers on Ebay, it sits in the darkroom mixed for months at a time and it's "good to the last drop". I use it in JOBO for sheet film and in a piece of sewer pipe for Cirkut films. YMMV

Andrew O'Neill

12-Mar-2019, 08:58

I used Rollo Pyro in BTZS tubes in the 90's, and it worked well. Stain is same as PMK... but... I didn't like it with HP5. I didn't like the look. I switched to Pyrocat-HD.

Tim V

12-Mar-2019, 12:00

Thanks for your help, everyone.

I've read over the info at The Unblinking Eye. Very informative, although I'm still not sure how I feel about the different stain colour of Pyrocat VS PMK. This is why I started looking at Rollo Pyro, which is a variant of PMK developed for Jobo processing but not suitable for tray processing. It sounds like all three options are viable and it might come down to personal bias or taste, but Pyrocat-HD is the most tried and tested of the three, with more online discussion history to draw from and help problem solve. I should probably follow that path in order to keep things easy on myself... But...

With regards to development time differences between HD and MC, are they effectively the same, or does the MC necessitate shorter time? If MC is formulated to be more suitable for rotary; i.e. it oxidises slower and I don't have to worry about dividing the development bath in two, then I'd just as sooner go that way to try and eliminate processing associated with oxidisation and developer exhaustion from the outset.

I'm still a bit confused though about how much solution to use in a fully loaded 3005 expert drum and at what point I'm stressing the Jobo motor and lift beyond what is reasonable. The maximum capacity of the 3005 drum is 1500ml (Sandy recommends at least 250ml per sheet = 1250ml minimum total,) and I'd be keen to fill to this point to help assure even development. I just wouldn't want to do this if it might result in burning out the motor or stripping gears, etc. I understand I could raise the drum and the lift with my hands, effectively reducing strain on the lift when draining the drum. It's mainly the motor I'd worry about.

If I'm reading correctly though, with 3005 tanks fully loaded with 8x10" film most people seem to develop in two baths of 1000ml, both for equal times? Is this simply as to avoid the effects of oxidisation and developer exhaustion? Do people still do this with Pyrocat-MC, or does it make more sense with MC–due to its differing formulation that reduces oxidisation as well as for economy of use–to simply put 1250ml minimum in the tank and develop in one bath?

Sorry, one million questions...

Vaughn

12-Mar-2019, 12:28

If Jobo says 1500ml is the limit for the 3005, then that's what the processor can handle -- remembering that Jobo says to hand-lift the tank.

I suppose you could use PyroCatHD at 2:2:100 for a shorter time -- you should be able to get away with one fill of 750 to 1000ml.

Pere Casals

12-Mar-2019, 12:31

not sure how I feel about the different stain colour of Pyrocat VS PMK. This is why I started looking at Rollo Pyro, which is a variant of PMK

You will find that Rollo creates a thiner stain than PMK.

You should realize what is the effect of the stain's color.

In VC paper the green stain prints with some lower contrast than the yellow stain, but this effect is modulated by the density amount, as a higer density in the negative it also contains an stronger filter.

You can compensate by adjusting the filtration in the enlarger, with (say) Pyrocat you may want to use a higher contrast grade than with PMK to obtain the same in the mid greys. But, as said, this effect depends on density in each spot, so after you compensate the printing grade you still will have a difference in the scene highlights: with Pyrocat (compared to PMK) hilights will print like if filter grade was a bit lower.

So at the end (IMHO) when burning highlights, with PyroCat, you will end using higher filter grade than with PMK. IMHO this is the difference.

If you find the Rollo stain is too thin... then if you move to a brown stain you would be adjusting two things in the printing: the filter grade to the general exposure, and the grade you use for burning highlights, you would be increasing the grade for both, but you would increase more the grade for burning hights that you did for the mids.

...so for equal results (brown vs greener stain) you need a different grade compensation for highlights than for mids,

Jim Galli

12-Mar-2019, 12:42

Tim, with 5 sheets of 8X10 film I always only use 850ml. The JOBO is a marginal pile of rubbish. But there's really nothing else so I keep on keeping on with them. My current machine has dying motor syndrome. I have to run a while and wait for things to warm up before I put a tank on. It's a complainy whiny lazy terd of a machine. But I love the results and there's nothing else like it. Wish they would build a robust version and re-make the $400 (could make them in China for about $33) tanks. :rolleyes: Love the concept. Hate the actual machines. I've replaced the troublesome mechanical reversing switch on both of mine with an electronic version. Most people don't experience the same as me because I use the hell out of mine.

Alan9940

12-Mar-2019, 13:28

Tim,

Development times between Pyrocat-HD and the -MC variant aren't significantly different. I found my times with -MC to be just slightly shorter, but not so much that one would even worry about it. I wouldn't worry too much about straining the motor; over the years, Jobo "beefed" up the motor and I'm sure the latest CPP-3 has the most capable motor. Don't use only the handle on the lift to raise/lower a full tank...especially the 3005! Reach under the carriage the drums spins on and provide more lift with that hand vs the one on the handle. Again, I have only ever run a single bath for either -HD or -MC and never had increased general stain working this way. YMMV, of course. I know others do the "two bath" thing and I'm sure it's for a very good reason. Personal testing will tell the tale as to what works for you.

Peter De Smidt

12-Mar-2019, 13:36

I've used the Pyrocat MC with 4x5 film in an expert drum with no issues. I don't like the super green/yellow stain of PMK, as it led to problems getting good highlight separation on multigrade papers, at least it did for me. Other people love it, and so your mileage may vary. For years, Jobo USA recommended no more than 1000ml in any of their tanks. Maybe the CPP-3 is stronger than any 2, although I don't know that. I have a CPP-2 with the strongest version motor. I would not use over 1000ml. Jim and I have similar opinions about Jobos.

angusparker

12-Mar-2019, 20:23

Another vote for HD. I find it works well in the Expert drums at minimum speed and 15% off MassiveDev times. Problems arise with any of the standard tanks meant for paper that can take film. Trying ULF sizes like 11x14 and 14x17 always leaves uneven development with HD because of the ridges inside. So I’ve just stuck with 8x10 in Expert drums where there is no issue and always use a non-staining developer with ULF in a Jobo. Tray development is probably best in ULF in any case.

Tim V

13-Mar-2019, 02:26

From what I've read the CPP-3 has a stronger motor and circuitry, the one from the ATL machines. I've emailed Catlabs who I'm buying the machine from to see what they say on the matter; what they recommend for max load, so will report back.

Interesting that not many people at all seem to use Rollo Pyro / ABC+. From all of your advise I'm leaning heavily towards Pyrocat-HD, especially because there is a lot more information on recommended developing times etc.

Angus, do feel that the times of Massive Dev chart are too long for rotary development? I'm guessing cutting the times by 15% suggests you're compensating for increased contrast due to continuous agitation? I'll have to check the times on there compared to those recommended by Sandy King and / or Photographers Formulary, for example.

In terms of the colour and affect of PMK stain, I've always liked it but it can't hurt trying something new. I'm interested to see how differently they print–as described earlier in the thread-and how much harder / easier they are to get where I want.

Pere Casals

13-Mar-2019, 05:22

Tray development is probably best in ULF in any case.

And also it's probably best in LF (IMHO) in many situations.

New SP-8×10+ is in the good direction to take a certain commercial opportunity.

188723

It allows the agitation control factor, and sheets can be added or removed at different times, in a single batch to process sheets with different N, or even different films requiring different times.

Of course rotary is also nice, specially when a fully automated processing is featured.

My view is that many people hated trays because processing was usually done in darkness, without realizing that the tray can be placed in a light-tight box, and that after we move the sheet to another stop tray we can do all lights open.

The great thing of future SP-8×10+ (or DIY equivalent) is that processing is pipelined, just after we move the tray content to the stop bath we may start another development. In fact this can also be done with a rotary, anyway.

Of course all depends on the job to be done and personal preference, but if I was happy with PMK and making 4x5 then my solution would be SP-8×10+: 4 sheets per batch, different times for different sheets, no oxydation, agitation control, no motor-knobs-cords-etc, daylight, fixing (clearing) time tracking, pipelined processing... cheap gear (DIY just we need a light-tight box).

Sometimes minimal is powerful.

Peter De Smidt

13-Mar-2019, 06:58

From what I've read the CPP-3 has a stronger motor and circuitry, the one from the ATL machines.

I was told the same thing about the last version of the CPP-2. I'll be interested to hear what you find out.

angusparker

13-Mar-2019, 17:25

And also it's probably best in LF (IMHO) in many situations.

New SP-8×10+ is in the good direction to take a certain commercial opportunity.

188723

It allows the agitation control factor, and sheets can be added or removed at different times, in a single batch to process sheets with different N, or even different films requiring different times.

Of course rotary is also nice, specially when a fully automated processing is featured.

My view is that many people hated trays because processing was usually done in darkness, without realizing that the tray can be placed in a light-tight box, and that after we move the sheet to another stop tray we can do all lights open.

The great thing of future SP-8×10+ (or DIY equivalent) is that processing is pipelined, just after we move the tray content to the stop bath we may start another development. In fact this can also be done with a rotary, anyway.

Of course all depends on the job to be done and personal preference, but if I was happy with PMK and making 4x5 then my solution would be SP-8×10+: 4 sheets per batch, different times for different sheets, no oxydation, agitation control, no motor-knobs-cords-etc, daylight, fixing (clearing) time tracking, pipelined processing... cheap gear (DIY just we need a light-tight box).

Sometimes minimal is powerful.

And if you are willing to spring for night vision goggles it doesn't even have to be in the dark with trays....

Steve Sherman

13-Mar-2019, 17:53

You will find that Rollo creates a thiner stain than PMK.

You should realize what is the effect of the stain's color.

In VC paper the green stain prints with some lower contrast than the yellow stain, but this effect is modulated by the density amount, as a higer density in the negative it also contains an stronger filter.

You can compensate by adjusting the filtration in the enlarger, with (say) Pyrocat you may want to use a higher contrast grade than with PMK to obtain the same in the mid greys. But, as said, this effect depends on density in each spot, so after you compensate the printing grade you still will have a difference in the scene highlights: with Pyrocat (compared to PMK) hilights will print like if filter grade was a bit lower.

So at the end (IMHO) when burning highlights, with PyroCat, you will end using higher filter grade than with PMK. IMHO this is the difference.

If you find the Rollo stain is too thin... then if you move to a brown stain you would be adjusting two things in the printing: the filter grade to the general exposure, and the grade you use for burning highlights, you would be increasing the grade for both, but you would increase more the grade for burning hights that you did for the mids.

...so for equal results (brown vs greener stain) you need a different grade compensation for highlights than for mids,

Hello Pere, possibly there is a mix up in the manner described in the printing end of PMK vs. PyroCat. PyroCat provides greater separation in almost all parts of the negative's tonal scale, especially in the mid-tones when compared with PMK processed negatives. As you say, PMK stain is Green while the stain of a PyroCat neg is Amber. The Green stain produces a slightly lower contrast print because of the Green stain and it's similar color to the low contrast filtration used in modern Multi-Contrast papers. This is especially true in the highlight region where the Green filtration will impact first and to the greatest degree pushing tonalities together rather than apart. PyroCat negatives are noticeably sharper which again produces an impression of greater micro contrast. This all stems back to the reducing agents of the two Pyros, PMK using PyroGallol acid, as does Rollo Pyro while PyroCat uses PyroCatechol as it's main reducing agent. Naturally, with a properly designed large format negative for each chemistry world class prints are possible. However, in my experience, significantly more flexibility is achieved with a PyroCat negative speaking specifically about the Silver Gelatin process.

Tim V

14-Mar-2019, 02:03

Thanks again all for chiming in and presenting opinions.

With regard to tray processing, that technique has been serving me very well except that I’m not confident processing more than one sheet at a time, as each time I’ve shuffled I’ve scratched film. When I shoot, I shoot a lot and it takes me weeks to get through my processing. At least with the Jobo I can confidently do at least five sheets or one run a day and print the previous days work while the next run is drying.

One reason I’ve been liking the PMK is actually the highlight compression.it has been giving my images a bit of a vintage look, especially on Bergger Warmtone CB semi-gloss, with its ivory base tint. I will give HD a go with the Jobo though, as I feel I now know what PMK does and it’s a good time to experiment with a different combination.

Tim V

14-Mar-2019, 02:24

PS: Catlabs said they recommend a max of 1000ml in the 3005 drum, and that even that is on the edge considering the weight of the actual drum even without chemistry.

My question then is, for Pyrocat-HD do people consider this too little chemistry to process 5x sheets of 8x10" film? If so, I take it this is why people dump mid-development then refill and continue for the rest of time with a fresh 1000ml?

Pere Casals

14-Mar-2019, 02:30

except that I’m not confident processing more than one sheet at a time, as each time I’ve shuffled I’ve scratched film.

You can use dividers in the tray
188762

You may use a light-tight box (or a paper safe) to operate daylight
188760

or an IR toy
188761

And, as said, after the sheets are in the stop tray you may continue lights open, while the developer trays (daylight type) may process more sheets in parallel.

For 8x10 we may operate more than one "daylight" tray at the same time.

Pere Casals

14-Mar-2019, 03:01

in my experience, significantly more flexibility is achieved with a PyroCat negative speaking specifically about the Silver Gelatin process.

Steve, I've witnessed your preference for Pyrocat, an this was the main factor in my choice.

IMHO it is with VC paper that we'll see the stain footprint, because stain color has an effect in the contrast and, as the stain is stronger as the densities are higher, then the stain works as a contrast mask that modifies paper grade depending on density in each spot.

I guess that at the end this is equivalent to modified (corrected) toe in the paper curve.

(Paper toe shows the highlights, that are in the film shoulder)

Fred L

14-Mar-2019, 04:55

if you're concerned about the weight of chemistry in the drum, you can just load 4 sheets instead of the 5, or use a different roller base. ( I use Simma bases) and not worry about the weight. Just keep in mind the drum has a tendency to walk off the roller base ;)

Steve Sherman

14-Mar-2019, 05:13

Thanks for responding Pere. I’m aware of the masking technique that Ross suggests as well as other more intricate masking systems. I believe my method of negative design and EMA processing eliminates the need for masking of any type. In my experience any introduction of Green stain or Green exposure with Multi-Contrast papers simply cannot be recovered in lost mid-tone contrast. I regularly pre flash MC papers so that I can reduce the Green exposure which is “projected” through the negative yielding an appreciable gain in mid tone contrast. Pre flashing paper with Green light is significantly different than projection of Green light through the various negative densities. So, starting with a negative producing a stain other than Green seems to negate the need for any sort of masking or other labor intensive and registration dependent techniques. Clearly, the Green stain is counter productive to the Silver printer but does not impact Alt processes using a UV light source. My understanding is that PyroCat may not be as readily available in Europe when compared with PMK and that can be a factor I don’t have to overcome.

Pere Casals

14-Mar-2019, 07:23

My understanding is that PyroCat may not be as readily available in Europe when compared with PMK and that can be a factor I don’t have to overcome.

Steve, there is no problem to mix pyrocat from raw chemicals, also there are at least some 4 ebay sellers (EU based) that make cheap 20L kits, some sell it mixed in bottles.

masking or other labor intensive and registration dependent techniques.

This is not USM, those color masks don't require a precise registration, in the same way that in burning/dodging (split grade) does not require precise boundaries, a mylar diffuser is placed in the middle, and the mask itself may be pretty diffuse.

I made preliminary tests by printing a transparency (mask) having yellow level proportional to the scanned density, it looks it may be really worth sometimes. But (to me) better if no digital mask is there....

Clearly, the Green stain is counter productive to the Silver printer

I try to realize that from the sensitometric effect. The stronger green in the high densities lowers more the contrast in the highlights than in the mids. This tends to compress highlights (with VC papers), this is not necessarily bad if at the end we would burn highlights with the 0 filter in the split grade.

But with EMA you do well that job in the development, of course one of the benefits of EMA is that the highlights are compressed from the local developer exhaustion, so in that case green is not of interest, but anyway it may help perhaps if the negative has high densities in the highlights from a regular development.

With higher stained green in the high densities then the VC paper sports a longer toe, of course paper toe is what shows the highlights (shoulder in the film ). IMHO it all depends on the paper toe extension we want.

What is clear is that the stain revival has a nice interaction with VC papers...

Steve Sherman

14-Mar-2019, 12:06

I believe we’ve gone off the OP original topic so I’ll check out for now

Pere Casals

14-Mar-2019, 12:30

I believe we’ve gone off the OP original topic so I’ll check out for now

Yes, a bit...

Anyway discusing stain color vs VC paper has been really interesting, what's about me I've realized that several factors are involved.

Tim V

20-Mar-2019, 02:20

Thanks again, guys for all of your advise. The discussion around effects of stain colour when printing with VC papers is facinating. Again, I think it's a good time for me to try different developer combinations, having been using PMK only with HP5 / FP4 for quite some time in various formats, although mainly 8x10". THrowing the new process variable of the Jobo CPP-3 in the mix is a bit dangerous, but PMK for rotary it seems. At least, I'm not keen on testing the reliability boundaries for myself, prefering to use something that people describe as 'bullet proof' and still leaves me with the qualities I'm used to, or near enough to it.

So going by all of the experience conveyed above, 1000ml of HD/MC mixed at 1:1:100 is enough to run 5 sheets in a 3005 drum... I guess maybe I'm paranoid because Sandy's instructions say at least 250ml per sheet, but maybe he's erring on the extra safe side? If group concensus is that 1000ml is enough to develop all five sheets in one fill of the drum, so be it. I'll give it a go!

If anyone out there is in fact splitting the development time into two baths, I'd like to hear from you and know how / why.

Thanks again, it's all of great help. I've never used a Jobo before and I already know it's going to be a revelation in more ways than one.

Tim V

1-Apr-2019, 12:16

A new CPP-3 and drums should be on the way to me in the next few days... Just in time, as I have 40+ 8x10" sheets of HP5+ I need to process.

Still a bit nervous about using only 1L of Pyrocat-HD (1:1:100) for 5 sheets... Maybe it's simply safer to process on 4 sheets at a time, that way I'm within Sandy's recommendation of 250ml of chemistry per sheet?

The other option is of course split the development bath into two 1L batches. For those that do this, is it simply a matter of emptying the first bath at the halfway point, refilling with the second bath and completing the development with it? Do you need to add any extra time to compensate for the time it takes to empty / refill, or are there any other tricks I need to be aware of? Potential pitfalls?

Thanks!

Peter De Smidt

1-Apr-2019, 12:38

Just use 4 sheets, until you have time to test. Honestly, if they're really valuable negatives, I would do all testing first.

agregov

1-Apr-2019, 13:28

Just use 4 sheets, until you have time to test. Honestly, if they're really valuable negatives, I would do all testing first.

I agree with Peter. I'm still new to 810 processing in a 3005 drum (CPP3 in my case). Omar at CatLabs also recommended 1000ml max. Talking one day to Rod Klukas (Arca) he suggested 4 sheets with the Expert drums. In my processing so far with PyroCat and C41, I feel my negs were slightly thinner than usual processing 5 sheets at a time. What is interesting is I process 10 4x5 negs in my 3010 with 500ml (2:2:100 or C41) with no issues (= 2.5 810 negs). So, in theory 5 810 negs with 1000ml should perform equally. So, far that hasn’t been my experience. Maybe you don’t get the same amount of agitation in a 3005 versus 3010? Also worth noting, I can see the motor straining some on my processor, even with the latest CPP3 motor. For longevity, it would probably be better to go with less chemistry. I am likely going to move to 4 sheets and see how that goes.

One related story, I took a workshop with Michael Smith several years ago and he scoffed at using a Jobo for 810 negs. He would process up to 14 810 negs at once in a 11x14 tray. He said he came back from trips with hundreds of negatives and processing in a Jobo would take forever. So there is still something to tray processing.

Jim Galli

1-Apr-2019, 13:43

I have done thousands of sheets of 8X10, 5 at a time using 850ml. The one thing you should research though is with FP4, HP5, PlusX, Tri-X, and even Efke 100 I always use 2:2:100. I use 1:1:100 on very slow contrasty film like Aerial Panatomic X where I'm actually trying to restrain development.

I agree, go shoot some stuff in the back yard that doesn't matter for your first trials.

Drew Wiley

1-Apr-2019, 14:21

Some of that stuff in the back yard is liable to eat me if I'm not careful! I just got done taking my big commercial weed whacker to it. If I don't keep things buzzed down this time of year, even the carnivorous St.Augustine grass is likely to strangle the porch cat in his sleep. But hidden from such terrors in my darkroom, back when I did experiment with film processing in drums, I preferred to fine tune dev activity via significant RPM options, and not just via time, dilution, and temp. My own gear-motors on the roller devices are set up to run at a considerable lower speed, if necessary, than say, something like a Jobo, which even at the lowest speed, seems awfully revved up. But I get more consistent results tray method.

JimL

1-Apr-2019, 15:19

One thing you can do to reduce the load on the Jobo's motor is to rotate in one direction only. Flip the little white reversing arm by the drive gear out of the way. I use mine this way with Expert drums and the lack of reversing doesn't seem to affect developing evenness as far as I can tell.

Tim V

2-Apr-2019, 01:02

Thanks all,

I’ll certainly do some tests first and probably start with 4 sheets rather than 5.

Jim Galli, when mixing HD at 2:2:100, how do you calculate times compared to 1:1:100 dilution? I was thinking this could be a good way to go too in order to combat exhaustion of chemistry, but don’t know where to start with regards to time. I’m currently using HP5+. Does Sandy give a formula for this?

EDIT: In an effort to find this out for myself, I revisited Sandy's article on The Unblinking Eye: https://unblinkingeye.com/Articles/PCat/PCat4/pcat4.html

Looking at Figure 20. HP5+, Pyrocat-HD mixed 2:2:100, processed for approximately 7.5mins @ 72 degrees F. should get me a CI of 0.52, which is desirable for VC silver printing. While I trust this is a good starting point, does this sound right to you? Seems a great place to start for processing 5 sheets at a time with 1L of total working solution–so more than needed as a safeguard, rather than bare minimum–so not to overload the motor and guard against exhaustion. Sandy states that with this dilution you can get away with 20% less working solution per sheet.

Jim Galli

2-Apr-2019, 09:52