Ilford Ilfosol S

“Veil & Whorls” by Tony McLean (Model: Jo Lamb)

Ilford FP4 Plus + Ilfosol S

There are still many excellent films and developers on the market today, and hundreds of permutations of those films and developers… enough, in fact, to keep the most ardent photographers and researchers occupied with their densitometers for a long time.

The choice of monochromatic films today is limited, but not too restricted, compared to a decade ago when this article was originally written, and it is a choice which is still quite interesting. Fast films with grain like full stops. Slow films with silken tones, and a number of specialist films for those occasions when we want something different to show our creative skills.

If we base our selection purely on economic grounds, then there are several films, usually from East European countries that will allow us to pursue our passion whilst keeping an eye on the pennies. However, I, like the majority of traditional photographers out there spend an inordinate amount of time seeking the “Holy Grail” of a film and developer combination.

Ilford FP4 Plus

To me FP4 Plus is a compromise and we English are reputed to enjoy this arrangement. It is a film with a distinctive ISO rating… however, we should be reminded to regard film manufacturers’ speed ratings with a pinch of salt. Nevertheless, I believe Ilford’s recommendation of ISO 125 is pretty close to the ideal – if not a little pessimistic. It is not the best choice of film for those who wish to push-process – its stable-mate HP5 Plus is rather more robust and forgiving in this respect, and those people who believe that a little extra development never did any harm had better watch out and prepare themselves for long printing sessions with much burning-in of highlight areas.

Ilfosol S developer

Ilfosol S is a liquid concentrate one-shot developer. It is probably an optimised derivative of Ilford’s once popular fine-grain developer ID-68. According to Ilford the active ingredients are based on the two developing agents Phenidone (1-phenyl-3-pyrazolidone) and hydroquinone (paradihydroxybenzene). Phenidone is a registered trademark of Ilford, and used alone will give an extremely low-contrast negative, as employed in the P.O.T.A. developer for high-contrast films such as Kodak Technical Pan. However, when partnered with hydroquinone the combined development effect effect is known as “superadditivity” where the whole is greater than the sum of the individual parts.

App “PQ” developers exhibit excellent keeping qualities, and when fresh Ilfosol S is an amber coloured liquid (like a pint of lager without the froth) which darkens slightly on exposure to air. I have found that it has a reasonably long shelf-life as long as certain elementary precautions are taken. I pierce the foil one with a needle and squirt the required amount into a graduate, replacing the cap and storing in a cool place. It is only available in 250ml bottles which is enough for a dozen films at a 1:14 dilution.

The recommended developing time at 20 degrees C at 1:9 is 4 minutes, which I find a little too short Thirty seconds extra development, or a one degree C increase in temperature, equates to a ten percent increase over the recommended development time… and a danger of producing those hard to burn-in highlights. A dilution of 1:14 gives us a six minute development time with the added benefits of increased acutance, and a greater margin to absorb any processing errors.


Agitation is important. Over-agitation leads to  higher contrast and negates the acutance effect which can be achieved by using diluted developers. Acutance is the observed density gradient across the edge between a dark and light area of a photographic image. Increased acutance is achieved where there is insufficient developer potential to allow replenishment of the exhausted solution in the rapidly developing highlights [BJP Annual 1963]. Too little agitation will lead to uneven development and “bromide streamers” – bands of extra density running across the width of the film, usually adjacent to the perforations. It is therefore good advice to follow the manufacturers’ recommendations for agitation , with perhaps a little less towards the end of the development period.

Acid or plain stop?

I prefer not to use an acid-based stop-bath. I am generally a kind person who does not wish to inflict pain on others – even inanimate objects such as films. The shock of suddenly introducing  an acid to abruptly curtail development is equivalent to an ice-cold morning dip! Better to use just plain water at 20 degrees C for two or three minutes with constant agitation for the first 30 seconds.

There are still many excellent films and developers on the market today, and hundreds of permutations of those films and developers… enough, in fact, to keep the most ardent photographers and researchers occupied with their densitometers for a long time. Subconsciously we all know that the vision and the final image are more important than the ultimate in technique. However, I am, and will remain a sucker for the manufacturers’ hyperbole and probably will continue to seek out the “Holy Grail” of film and developer combination… or maybe I will just stick to the good old FP4 Plus and Ilfosol S combination and spend a little more time taking photographs.


Ilfosol 3, officially launched in February 2008, is an enhanced formulation of the one-shot, general-purpose, liquid older black-and-white film developer Ilfosol S.

The new developer is particularly suited for use with medium and slow speed films such as Ilford’s Pan F Plus, FP4 Plus and Delta 100 Pro where it ensures a fine grain and optimal sharpness at full film speed. It is supplied as a concentrate in economical 500ml bottles and is diluted (typically at a ratio of 1:9) for one-shot use. However, for greater economy, Ilfosol 3 can also be used with many films at a higher dilution of 1:14 with only a small trade off in image quality.

Image and text © 1997-2012 Tony McLean

This article was originally published in “Darkroom User” magazine in 1997 by Tony McLean, whose superb British bird and wildlife images can be found on Flickr and East Yorkshire Wildlife Diary.

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