510 Pyro

510 Pyro is one of the new generation of staining and tanning developers, and said to be similar to pyrocat or PMK. It has been formulated by Jay DeFehr in the USA and arrived on the scene with claims of very fine grain, high acutance, good stain, and extreme longevity (as a single stock). Slowly, as the developer became more widely known, a following took shape with many photographers reporting good results with both normal development, stand and semi-stand techniques. Remarkably, the developer is used at dilutions from 1+100 or 1+200 for normal development, and up to 1+500 for stand development (move over Rodinal!).

The basis of 510 is Pyrogallol, normally a rather slow and unstable developing agent providing poor film speed. To counter this,  Ascorbic acid and Phenidone are added. These are additive developing agents with the phenidone probably boosting the film speed to normal/near normal. Interestingly, the ascorbic probably acts as a good antioxidant as the developer works. Certainly 510 doesn't seem to oxidize as quickly as PMK in use; 510 coming out of the developing tank after use about the same straw color that it went in. 

Pyrogallol is of course the second oldest developing agent ever used (after gallic acid) and was first discovered by a Frenchman named V. Regnault in 1851. Subsequently, it became a very popular in the late 19th century until displaced by the ubiquitous Metol in the 20th century as films got somewhat smaller and therefore grain became an issue. However, pyrogallol is almost as active as metol ("La Technique Photographique" P. 241) and has two great benefits over metol. These benefits are:

1. the oxidization stain created by Pyro, that becomes a natural filter to tame highlights and ease printing
2. the tanning/hardening of the gelatin emulsion which protects the negative and reduces developer movement creating more acutance in the image, even when rotary processed.  

These two benefits are enormous if done right; and so the hunt for a way to use Pyro has continued for a century. 510 Pyro claims to have achieved not only these two benefits (after all PMK did in 1991 right?) but also the Holy Grail of photography, ultra fine grain. But there's more, it's a one solution stock (no mixing A, B and sometimes even C solutions) and it keeps for years. 
So let's just take stock of this situation (pun intended), ultra fine grain, high acutance and that beautiful  Pyro stain, only one solution, doesn't go off in the cupboard...is this sounding too good to be true? 

That's a long list of impressive claims so maybe it's time we looked at DeFehr's 510 more closely and gave it a run for it's money against the big boys of modern staining developers PMK and Pyrocat.

Formula for 510-Pyro stock

TEA (Triethanolamine) 75ml warmed in microwave
Ascorbic Acid 5g
Pyrogallol 10g
Phenidone 0.25g
TEA to make 100ml

Use 1+100 through 1+500 with water.

The developer is designed to be extremely long lasting as stock. TEA, the organic solvent, is now well know as a preservative after the great work by Pat Gainer in this field. Unlike water, TEA does not dissolve oxygen and therefore protects the developing agents for, well, donkeys years. 

The developing agents used in 510 are Ascorbic acid, Pyrogallol and Phenidone. An unusual combination. I don't know of any other developer that has three developing agents. Of course, utilizing TEA as a solvent removes the need for an anti-oxidant/preservative, so theirs no sulfite required. The TEA also provides the alkalinity to activate the developing agents so no accelerator required. 

All this makes a developer that is very simple to make and use - just one solution to bottle; mix with water and it's ready. Add to this the extreme longevity and the very high dilution and you could have a winner on your hands. But winning developers need more than just simplicity of use and longevity, they need to produce the goods on the negative and be either on a par with the competition or better.
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510-Pyro with Acros at 80ISO. Developed for 9 mins at 23C. Dilution 1+200. Agitation first 30 seconds, then 5 seconds every 30.

Making up the formula

Making the developer is very simple but precautions must be taken with the Pyrogallol in particular. This, after all, is a poisonous chemical. Therefore you must wear gloves, a mask and eye protection and never make this up in a food preparation area like the kitchen.
Start by measuring 75-80ml TEA into a pyrex heat proof container. I use a chemical mixing jar. Then heat the TEA in the microwave for 30 seconds. It will get VERY hot. Carefully remove it from the microwave and add the ascorbic acid. This will dissolve quite rapidly with stirring. Then add the Pyrogallol which too dissolves quite rapidly. Then add the Phenidone. This proves somewhat harder to get into solution (doesn't it always!). I had to reheat the TEA a couple more times, stiring in between, to get most of my Phenidone to dissolve.
Finally I gave up and allowed the TEA to cool before decanting it into a brown bottle.There were only a few specs floating around and these dissolved over the next hour or so. All in all the whole process was done within 30 minutes and I had 100 ml of 510 Pyro.

1. Grain, what grain?

Frankly, I was shocked! 510-Pyro has extremely fine grain. Shown below, the grain is almost imperceptible when scanned with my Coolscan 9000 at 4000dpi. It's quite amazing the difference between the 510 grain and the PMK and Pyrocat-HD grain at exactly the same enlargement! None of the below crops were sharpened. All are zoomed in to 87% in photoshop. All were scanned from 2 1/4 square Rollei SL66 negatives - Fuji Acros film.
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510 Pyro with Acros - grain enlarged from above photo.

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PMK with Acros - grain enlarged from similar photo.

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Pyrocat-HD with Acros - grain enlarged from similar photo - same enlargement.

The fine grain of 510 was a surprise. I certainly didn't expect there to be such a difference - after all, PMK and Pyrocat are neither slouches in the grain department; but the pictures tell the story. Pyrocat-HD was the closer of the two but still noticeably grainier.

For interest I'm including below a crop of Acros developed in HC-110. This is a generic developer used by many so should give you a good idea of where we are with 510-Pyro - and how advanced this developer is.
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HC110 with Acros 100 grain enlarged from similar photo - same enlargement.

If you compare this crop (also at 87% enlargement) to the crops above you will see that the grain is somewhere between PMK and Pyrocat but the sharpness is noticeably less. This is typical of a softer working general purpose developer like HC-110 and D-76 which both create wonderfully creamy tones but poor sharpness in comparison to acutance developers.