Prescysol EF

Pictorial Planet

Peter Hogan's Prescysol EFTM

Available from my shop here. Please order in the shop or email me if your country is not in the database for postage.

Prescysol EF (Extra Fine) is a unique extra-fine grain pyro-glycin developer incorporating special photographic glycin for extended tonality and pyrocatechin for tanning, staining, and high acutance. Formulated for smaller film sizes such as 35mm film, but equally at home with medium and large format films, the beautiful tonality of a glycin film developer together with the benefits of a pyro developer is now available for your use.

This unique formula by Peter Hogan, Prescysol EF™, offers the same tanning, staining, sharpness, and highlight control of Prescysol™. But, with the experience of Barry Thornton's formulas, Hogan carefully added the special, and very expensive, developing agent, photographic glycin, to Prescysol EF™ creating finer grained negatives with longer tonality. If you want finer grain in your photographs, and still want to enjoy the benefits of pyro staining, tanning and acutance, you need look no further than Prescysol EF™.

Prescysol EF™ is also an extremely tolerant developer. You can develop films of different makes and speeds together for the same time.

Sold in 2 x 100ml bottle for use at 1+1+100.

This quantity is sufficient for up to 33 rolls of 35mm film, or 40 rolls of 120 film (if the 120 film is loaded two to a spiral). 

Let's see what Peter Hogan says about this developer:

Prescysol EF™ is a specially formulated developer unsurpassed in its ability to provide superb negatives with extremely fine grain, the highest available sharpness, smoothly gradated tones and delicate and translucent highlights. Prescysol EF yields full film speed; you can expose at the makers recommended ISO.

Prescysol EF™ is an advanced tanning and staining developer. As the developer is absorbed, the emulsion is tanned, or hardened, and this hardening is variable, being greater in areas of greater exposure. As the emulsion tans, it inhibits the absorption of further amounts of the developing agent, and so development in these highlight areas is restrained. The lower tanning action in the shadow areas allows development to continue and these areas continue to build, producing negatives with rich, deep shadows, beautifully gradated mid-tones, and delicate highlights. Negatives developed in Prescysol EF™, particularly using the partial stand method, will yield full speed, exhibit high acutance, and will need considerably less burning-in to areas such as skies.

As development proceeds, oxidation and natural by-products of the process stain the emulsion brown, the staining being proportional to the exposure level of the various parts of the negative. The result is a continuously-variable mask of printing density across the tonal range of the negative. Further, as the emulsion is stained mostly
between the silver grains the effect is to soften the grain and so produce a smoother tonality in large areas such as sky and mist, where grain can normally be such a problem. Prescysol EF is an extremely tolerant developer; films of different make and speed can be developed together at the same time.

For example, HP5 400 (120 roll film) and Delta 100 (35mm) despite being of totally different grain structure and speed, can be developed together in the same tank for the same time. In fact, the modern tabular grain films (which require closer control of times and temperatures in normal developers and are more susceptible to burned highlights and blocked shadows) will benefit enormously from being developed in Prescysol EF™, yielding the fine grain, tone and acutance of which these films are capable.


Prescysol EF™ is supplied as two concentrates which are diluted and mixed for use; a 100ml bottle of part A and a 100ml bottle of part B. This quantity is sufficient for up to 33 rolls of 35mm film, or 40 rolls of 120 film (if the 120 film is loaded two to a spiral). When fresh, part A will have a very light straw colour, and will go very dark brown as it deteriorates. Do not use it if it has gone dark brown. It will keep, in the bottle supplied and if an anti-oxidation spray has been used, for at least six months. If you wish to keep it longer, it is best to decant it into a brown glass bottle and use an anti-oxidation spray. Always store part A away from light. Part B is a clear(ish) liquid, and will keep indefinitely in the bottle supplied.



All development is carried out at 24 degrees C in small tanks. We recommend that you pre-soak the film for five minutes in water at the same temperature. With 120 roll film this soak will also remove the anti-halation dyes from the film.

Prescysol EF is mixed in the proportions 1+1+100, so for 35mm film mix 3ml of Part A with 300ml water. Then add 3ml part B and stir. For 120 film, regardless of whether you have one or two films loaded on the same reel, you mix 5ml part A with 500ml water and then add 5ml part B and stir.

Note: in all cases we strongly recommend the use of distilled water. Tap water has too many additives, ph varies, and consistent, streak free negatives can not be guaranteed with tap water.

To mix: Pour the measured amount of water, at 24 degrees C, into a clean container, and add the requisite amount of part A. Measure out and add part B and stir. Pour out the pre-soak, and pour the developer into the tank. As part B is added, the developer may start to darken and this is quite normal. Agitate continuously for the first 60 seconds, and then for 10 seconds every 30 seconds thereafter. (Agitation should not be too vigorous; a gentle inversion followed by a slight 'swirl', turned upright and 'swirled' again is sufficient. Two such manoeuvres every 30 seconds is ideal. The 'swirl' is a slight rotary movement of the drum sufficient to induce a
small sideways movement in the liquid. (This is to break up laminar flow and so prevent bromide drag - the streaking that results in all development if progressively exhausted developer is allowed to follow one path repeatedly) Development times are remarkably consistent for all films; 8 minutes is a good starting point and will produce extremely easily-printable negatives. 10 seconds before the elapsed time start to pour out the developer. The after-soak in used developer needed by other staining developers is not required with Prescysol EF™, and as this is one-shot, you can discard it. The used developer will normally be a much darker colour at this point.


Staining developers work best in an alkaline environment, and an acid stop bath will reduce the stain.

Four or five, 10 second rinses in fresh water at the same temperature as the developer is ok, or you can use our unique

We recommend using freshly-mixed fixer, and our own
Alkali-FIX™ is specially formulated to enhance the staining characteristics of Prescysol EF™.

Staining developers can require longer fixing. Fix for 5 minutes in
Alkali-FIX™ and inspect the film. If there is any cloudiness, fix until it is removed and then continue to fix for the same length of time again. If there’s no cloudiness then fixing is complete.

A running water wash is always better, but beware of suspended particles in the water; always use a filter. There is absolutely no requirement to use a Hypo-clearing agent when using alkali fixes, and they should not be used. If you have used
Alkali-FIX™ a four minute wash is ample, otherwise wash as recommended by the maker of the fixer used.
If you are using tabular grain films eg, T-Max, Delta, with
acid fixers, DO NOT extend the fixing time in an effort to dissolve the extra dye used in these films. Simply let the film sit in 3 x 5 minute water baths after fixing and before washing. Any residual dye not cleared by these baths will be cleared by a short extension to the washing time. Use of a wetting agent is by choice, and hang to dry.


This is the recommended method of development. Negatives developed using the partial stand method will show smoother grain, higher acutance (apparent sharpness) and hold more highlight detail, meaning easier printing, than the 'normal' method. The dilutions, mixing and temperatures are the same as for the normal agitation method.

Pour in the developer and agitate for the first 60 seconds, then for 10 seconds
every 3 minutes. Allow the tank to stand undisturbed between agitations. Starting time is 10.5 minutes. There will be a longer stand time at the end; that is ok.

The rest of the procedure
is as for normal agitation. As always, we recommend that for ultimate control and results that you perform standard tests to discern your personal film speed and development times. However, Prescysol EF™ is so forgiving and tolerant that using the makers ISO and following our instructions will yield superb negatives for the vast majority of applications, and far better than any normal developer.


Treat all chemicals with caution and keep out of the reach of children. Do not store chemicals in bottles designed for other use, e.g. lemonade bottles.

Use gloves during use, and wash from the skin with plenty of fresh water. In case of contact with the eyes, wash with plenty of fresh water and seek medical advice. Wipe up spills immediately and wash or swab with clean water.


No liability is accepted by the producer or supplier of this product except for the value of the product itself if faulty.
Expressly, no liability can be accepted for any consequential loss or injury howsoever caused. The producer/supplier will be pleased to refund the full purchase price provided the faulty product is returned within 30 days from date of purchase. Use of the product implies acceptance of these conditions.

© Peter Hogan. No part of this document may be reproduced in any form without written permission.