Phenidone vs. Metol--grain : LUSENET : B&W Photo - Film & Processing : One Thread

I saw a recent post which mentioned that phenidone produces more grain than metol. I had heard that some PQ formulas don't yield as sharp results as MQ, but I have never heard anything about a grain difference. Any comments based on subjective practical results or analytical test results would be appreciated.

-- Ted Kaufman (, July 17, 2001


One speculation.

Superadditive effect of PQ is very strong and I feel PQ developers must be very carefully designed to tame this wild combination. One problem I had with PQ formulae that I thought were not well optimized was gradation that wasn't clean and beautiful. One way to tame this could be to buffer the developer, and this could lead to lack of subjective sense of sharpness. Phenidone-ascorbic acid superadditivity seems to be much easier to control and they also seem to result in noticeably finer grain than PQ. In this sense I think hydroquinone and ascorbic acid are very different.

Some people are crazy about phenidone-glycin type developers and I hope those people can describe why they love those compared to MQ, PQ and P-V.C. types.

-- Ryuji Suzuki (, July 18, 2001.

I forgot that Microphen is a PQ that produces somewhat coarser grain than ID-11. I think Microphen 1+1 or 1+2 are very good for TMX, especially for nightscape applications. With HP5+ Microphen makes bigger grain than ID-11, probably because, in part, bigger grain than what's already quite visible is really noticeable.

-- Ryuji Suzuki (, July 18, 2001.

I think Ryuji has hit the nail on the head. Sharpness in development refers to adjacency effects. Adjacency effects rely upon a controlled decomposition of the developing agent. PQ combinations are more superadditive than MQ combinations. Since Phenidone is so effectively regenrated by Hydroquinone, the exhaustion rate is vastly lower, which probably accounts for the proposed lower sharpness i.e., no local exhaustion takes place. The trouble is phenidone on its own as the sole developing agent is problematic. It doesn't keep very well and produces very low contrast - POTA, a developer to provide pictorial gradation from document film, is a phenidone only developer that takes advantage of this property but otherwise for normal film, phenidone only developers are typically unusable. An advantage phenidone does provide is that it is said to provide a genuine speed increase of about half a stop (this parallels my experience). I've used a fair bit of Mytol, a phenidone - ascorbic acid developer. There is an increase in speed and apparent sharpness over other solvent developers like D23 but I haven't seen the adjacency effects provided by an adjacency developer like Rodinal or FX2 (but keep in mind that this is my subjective opinion). Single developing agent formulae are the ones that give us a good idea about individual developing agents. Once you start combining developing agents, the interactions between them can provide very different effects from the individual agents themselves. Cheers, DJ.

-- N Dhananjay (, July 18, 2001.

Thanks for your comments, RS and DJ.

I was rushed when I made the post and I really didn't state my question properly. I meant to question whether there was an appreciable difference, with respect to grain, between properly formulated developers using metol or phenidone. I didn't mean, necessarily, MQ or PQ. In fact, specifically, I'm thinking in terms of developers that do not have hydroquinone at all.

For example, let's take the Pyrocat-HD formula. As I understand it, the original formula called for 1g sod. bisulfite, 5g catechol, 0.2g pot. bromide and 0.2g phenidone / 100ml water to form the "A" solution. I have seen metol suggested as substitution for phenidone. I believe I read 1g of metol instead of 0.2g phenidone. (From my own experience, however, I think it would take 2-3g of metol to achieve the same activity, but let's assume for the sake of discussion that 1g of metol = 0.2g of phenidone.)

So my question is: Has anyone used Pyrocat-HD, or any other developer where phenidone or metol has been replaced by the other (assuming a substitution that amount yields an equally balanced formula). Then, comparing those two formulas, what differences--if any--were observed in terms of grain and/or sharpness. Also, did phenidone provide enhanced shadow detail over metol, as is commonly believed?

-- Ted Kaufman (, July 26, 2001.

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