510-pyro vs Obsidian Aqua

What is the difference between the two. You still have a lot of folks that use and like 510-Pyro, but you hardly hear a peep about Obsidian Aqua. I sure remember the word wars between Sandy King and Jay DeFehr and don't want this to go anywhere near those wars. I just want to know if anybody here has any experience, good or bad, with these two developers?
I never got into either of these developers and went instead to the Pyrocat versions H, MC and finally HDC. I do most of my film developing and photo work at my cottage where my wife and I will eventually move to permanently. I still have a functional darkroom at our home in the south and on occasional a stay like to develop a roll or two. I get tired of lugging things back and fourth so decided to mix a developer with long shelf life for down south. Long shelf life was important since I don't get down there very often. I thought why not try 510-Pyro since it will fit my requirements. Yes, I could split my Pyrocat-HDC, but I wanted to try 510-Pyro anyway since I never really did. Well, to make a long story short I mixed some and ran a roll of Tmax 100 in 120 through 510-Pyro and was very pleased with the results. I hear folks say they don't get full speed and was a little worried, but I needed not to worry. The negatives were very nice and very sharp. The only thing I noticed was I had to print on grade 3-3 1/2 setting on my Ilfospeed 400 VC head. Not a problem I can't fix, but it surprised me a little. I'm just curious as to what the real differences are between the two developers is all.

Hi John, 510-Pyro is an excellent developer, that I have been using for a few years, on and off. Mixed in TEA, it has an indefinite shelf-life...just like Pyrocat-HD/C in Glycol.
I have also used Obsidian Aqua, and found it to give razor sharp negatives. I made a video a couple years ago...
Happy Holidays!

Andrew O'Neill said:

Hi John, 510-Pyro is an excellent developer, that I have been using for a few years, on and off. Mixed in TEA, it has an indefinite shelf-life...just like Pyrocat-HD/C in Glycol.
I have also used Obsidian Aqua, and found it to give razor sharp negatives. I made a video a couple years ago...
Happy Holidays!

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Thanks Andy! I see you were up very early this Christmas morning. Wrapping the last gift for the little lady??
I never really tried either one of these and decided to try 510-Pyro on a whim and if it worked find I'd leave it downstate. I must say it worked really fine and worth the effort of mixing it. It's a little on the thick side, but a little warming it makes it easier to measure out. I'll dig up your videos and watch them while I have my donuts and coffee. Thanks again and have a Merry Christmas!

I'm always up at 04:30/05:00. A habit started years ago. The downside is nodding off while watching Netflix at 8 LOL!
Here's the link to the Obsidian Aqua video...
Merry Christmas to you and your wife!

I've used Zone Imaging 510Pyro, and a developer sold as Colin (by Nik&Trick jn the uk), which is basically OA. If memory serves, OA is non-staining, which put me off in the end (I like staining devs for half frame). OA is two part, which i dont mind, but some don't like. It is very sharp.
The yellow hint to the 510 stain is supposed to help printing of dense negs on VC papers, but I've not seen much actual demonstrated evidence.
Another interesting developer in this area is Bellini's Nucleol, two part, very fine grained. Also non staining.
One possible consideration is that 510 Pyro and Nucleol both have extensive datasheets with tested times. That's not so much the case with OA

I have used both, and wound up using 510-Pyro more than OA -- but that doesn't mean I didn't like the results with OA, I just found it more unpredictable, e.g., one time OA actually lifted the emulsion off some Acros 120. I usually shot OA at half the state film speed, Neopan 400 at 200, for example, whereas I could get more speed out of 510P. I will say that OA is sharp, and I liked the tonality -- I may take a shot at using it again -- I'm attaching a photo developed in OA from about a decade ago. I do like 510P, which I usually use unstained -- you can unstain 510P using sodium sulfite; here are Jay's instructions:

The procedure is very simple and requires only sodium sulfite. To unstain 510-Pyro, dilute with a sodium sulfite solution instead of plain water. A 2% solution (20g/liter) of sulfite will unstain your 510-Pyro and retain most of the sharpness you're used to seeing, while a 10% solution (100g/liter) is enough to produce the solvent effect of a fine grain developer. A drop or two of 1% benzotriazole in a liter of working solution will clear some of the fog without significantly affecting contrast or film speed.

To make 1 liter of unstained 510-Pyro, 1:100, fine grain working solution:
Water 750ml
sodium sulfite 100g
510-Pyro concentrate 10ml
water to 1 liter
Use normal development times for 510-Pyro 1:100.
It should be possible to develop several rolls of film/ liter of working solution, and even to replenish the solution with concentrate, but I haven't tested these options.

Trask said:

I have used both, and wound up using 510-Pyro more than OA -- but that doesn't mean I didn't like the results with OA, I just found it more unpredictable, e.g., one time OA actually lifted the emulsion off some Acros 120. I usually shot OA at half the state film speed, Neopan 400 at 200, for example, whereas I could get more speed out of 510P. I will say that OA is sharp, and I liked the tonality -- I may take a shot at using it again -- I'm attaching a photo developed in OA from about a decade ago. I do like 510P, which I usually use unstained -- you can unstain 510P using sodium sulfite; here are Jay's instructions:

The procedure is very simple and requires only sodium sulfite. To unstain 510-Pyro, dilute with a sodium sulfite solution instead of plain water. A 2% solution (20g/liter) of sulfite will unstain your 510-Pyro and retain most of the sharpness you're used to seeing, while a 10% solution (100g/liter) is enough to produce the solvent effect of a fine grain developer. A drop or two of 1% benzotriazole in a liter of working solution will clear some of the fog without significantly affecting contrast or film speed.

To make 1 liter of unstained 510-Pyro, 1:100, fine grain working solution:
Water 750ml
sodium sulfite 100g
510-Pyro concentrate 10ml
water to 1 liter
Use normal development times for 510-Pyro 1:100.
It should be possible to develop several rolls of film/ liter of working solution, and even to replenish the solution with concentrate, but I haven't tested these options.

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That's a very good representation of what OA can do. I've never tried it and as you say, there is not much information out there on OA. I'm curious as to why you "unstained" 510-Pyro? Most everyone I read using it does so because it's a staining developer. As for getting box speed from films with 510-pyro and not getting it is a matter of individual metering and developing technique in my opinion. The only roll I've done in 510-Pyro was Tmax 100 120, which I rated at EI64. I metered for my shadows with a Pentax digital spot meter, developed for 9 min @ 70F with vigorous 30sec agitation and then 5sec gentle every 30sec. Oh, and no prewash! Like I said earlier, the negatives were sharp, very well exposed, but seemingly a little lower in contrast. Yes, so far I like 510-Pyro very much and the long shelf life is a plus.

I can only speak about Obsidian Aqua.

It reduces film speed by about a stop, and suppresses grain remarkably well. It definitely stains negatives. I found that the stock solution only lasted a few months, which is why I stopped using it.

I've used 510-Pyro for years and played around briefly with OA many years ago. Like others have already mentioned, I found OA to produce very sharp negs. But, since I mix all of the formulas that I use I found the mixing instructions for OA to be very confusing and stopped using it. Probably just me addled brain, but I never could wrap my head around it.

I watched Andy's videos on Obsidian Aqua and 510-Pyro and they were very informative. One thing I learned was Obsidian Aqua might not be something I want. I have plenty of propylene glycol and would instead make Hypercat, which is much the same only made with glycol instead of water. Another thing I noticed from Andy's 510-Pyro video is that he used .375 grams of Phenidone where I used the formula out of the 3rd edition of the Darkroom Cookbook that calls for .25 grams. I didn't know there was a change in the formula? I wouldn't think the difference in the amount of Phenidone would have anything to do with my lower contrast negatives, but maybe it does. Why was the amount of Phenidone increased?

OA is a nice developer if one doesn't mind speed loss. Easy to make, requires less components than Pyrocat-HD, produces subtle stain and gives super sharp results.

510-Pyro is relatively more complicated to make, more prone to failures, suffers from similar speed loss, more complicated to use due to its viscousity, arguably more toxic, produces noticeable stain and gives very decent results.

510-Pyro formula was revised by Jay to increase the amount of Phenidone. Not sure if he gave any reason for the increase, he might have somewhere.

Raghu Kuvempunagar said:

OA is a nice developer if one doesn't mind speed loss. Easy to make, requires less components than Pyrocat-HD, produces subtle stain and gives super sharp results.

510-Pyro is relatively more complicated to make, more prone to failures, suffers from similar speed loss, more complicated to use due to its viscousity, arguably more toxic, produces noticeable stain and gives very decent results.

510-Pyro formula was revised by Jay to increase the amount of Phenidone. Not sure if he gave any reason for the increase, he might have somewhere.

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I have been doing some searching to find the reason for the increase in Phenidone, but the only reason I have found mentioned was "consistency". I don't know what that means exactly, but would guess it has to do with consistency of weight measurement. Just guessing like I said.

John Wiegerink said:

I have been doing some searching to find the reason for the increase in Phenidone, but the only reason I have found mentioned was "consistency".

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Jay is active on Flickr where he posts new pics and responds to comments. You can ask him and find out the real reason for the increase, perhaps.

John Wiegerink said:

I have been doing some searching to find the reason for the increase in Phenidone, but the only reason I have found mentioned was "consistency". I don't know what that means exactly, but would guess it has to do with consistency of weight measurement. Just guessing like I said.

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Intuitively you wouldn't imagine that 0.375 with measurement to three decimal places would give any greater consistency than 0.25 to two decimal places or I wouldn't anyway so might consistency encompass other things?

I don't know either, it's just a thought

pentaxuser

pentaxuser said:

Intuitively you wouldn't imagine that 0.375 with measurement to three decimal places would give any greater consistency than 0.25 to two decimal places or I wouldn't anyway so might consistency encompass other things?

I don't know either, it's just a thought

pentaxuser

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That was my thinking too, but you never know. I'll do some more searching later in the day and see what I come up with.

revdoc said:

I can only speak about Obsidian Aqua.

It reduces film speed by about a stop, and suppresses grain remarkably well.

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What is the advantage over Perceptol?

Craig said:

What is the advantage over Perceptol?

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OA has a published formula, with relatively safe and easy to get ingredients.

Craig said:

What is the advantage over Perceptol?

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I have no first hand experience with OA, but from the pictures I've seen posted it might be a tad bit sharper. I have used Hypercat, which is supposed to. be like OA and that is razor sharp.

Raghu Kuvempunagar said:

.....

510-Pyro formula was revised by Jay to increase the amount of Phenidone. Not sure if he gave any reason for the increase, he might have somewhere.

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I tried it before the increase in phenidone was announced, and I found the shadow detail to be extremely deficient. I estimated the speed of the 400 speed film to be well under 200 (I don't remember if it was Neopan400 or HP5+ because it was around the time I was looking for an alternative to the Neopan).

So maybe the extra phenidone was to boost the speed?

john_s said:

I tried it before the increase in phenidone was announced, and I found the shadow detail to be extremely deficient. I estimated the speed of the 400 speed film to be well under 200 (I don't remember if it was Neopan400 or HP5+ because it was around the time I was looking for an alternative to the Neopan).

So maybe the extra phenidone was to boost the speed?

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I used the .25 Phenidone version with Tmax 100 rated at EI64 for 9 min @ 70F and I had no problem with thin shadows, but did have to use G3 to 3 1/2 VC setting with Fomabrom Variant 111 developed in ID-62 1+3.

john_s said:

So maybe the extra phenidone was to boost the speed?

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Possibly. The revision to the formula happened several years after the original formula was published which makes me think that user feedback played some role.

Initially 510-Pyro was meant to be used at dilution 1:100 and with sufficient agitation. But stand, semi-stand, extreme minimal agitation enthusiasts started using the developer at dilution 1:500. At such a very high dilution, the low amount of Phenidone in the original formulation could have caused some problems that were not so obvious at dilution 1:100.