Crawley’s FX 4

July 6, 2026 Pictorial Planet 1 Comment

FX 4 was always a problem developer for me. Well, maybe “problem” is too strong a word. I guess, as I look back on it, I was really the problem.

FX 4 1+1 with FP4 Plus EI125 7 minutes Ilford agitation

FX 4 Introduction

I’m a curious darkroom worker, curious about how thing work, how are they made, and why things are the way they are. I guess it was this curiosity that got me interested in Geoffrey Crawley and his FX series. To me he thought things through differently to other photographic chemists and the more I read his work the more I agreed with his way of thinking.

Crawley was shaking things up a bit with the idea that 35mm shouldn’t have to be a second class citizen; that it was sharpness which created more image impact and not fine grain – that quality so many photographers (and developer formulators) were attracted to.

So, it was with this mindset that every so often I’d get curious and check out one of his developers. Crawley developers have bags of character and every one of them is different. Frankly, there’s not a bad one (although I have my preferences) and actually there’s some excellent ones that out-perform developers by even the likes of the behemoth in the photographic field, Kodak! It’s a shame that much of the world never really got to use Crawley’s formulations due mostly to poor distribution by Paterson and of course Kodak’s massive marketing machine.

On this occasion I mixed some FX 4 and tested it on some film – and to my shock I didn’t like it at all!

I should have known something was wrong but tossed the developer and moved on. I was young and impetuous (at least that’s my excuse now) and was probably had unconscious bias, comparing it to something else like Acutol. But I should have known something was wrong.

This is what I thought:

It was slow! I was only getting box speed.
It was a bit grainy! This was supposed to be fine grain but I didn’t experience that.
It was too contrasty. It was supposed to give better tonality but I wasn’t impressed.

FX 4 1+1 with FP4 Plus EI125 7 minutes Ilford agitation

Well, if you haven’t guessed yet, all this was because I was using it all wrong. A lesson I learned much later on was that all developers need to be learned and not just used – it takes time, testing, and a few rolls of film. But, being young and far more impatient than I am now, I wrote the developer off and never went back to FX 4, at least until this series.

Now I find FX 4 isn’t that bad at all. Ok, it’s not his best solvent developer, that, I think, came sometime later, but for the 1960s, FX 4 was very good and very innovative.

So, with that background, let’s look a little deeper at this important developer.

Crawley’s first solvent developers

Whereas Crawley’s FX 3 (elsewhere on this blog) was an improved Adox MQ Borax formula FX 4 was all new. This was Crawley’s first real attempt at improving on the speed-grain-acutance interlock with a solvent developer. To do this he used a technique that I believe became his signature, what I call the Crawley triple developer combination. His unique triple combination of the developing agents metol, phenidone, supported by the super-additive hydroquinone. This triple developer idea was to become one of Crawley’s most important developer styles. As I think about it I remember he was mocked on-line by other more traditional formulators and photographic technicians for these innovative ideas but Crawley was onto something they simply didn’t understand and this three developing agent chemistry became a very effective method of formulation in some of the best of the FX range.

After FX 1, FX 2, and FX 3, number 4 was arguably Crawley’s most complex and carefully balanced developer in the range yet. It came with a much more controlled development action and was certainly an attempt at formulating a developer that:

Improved pictorial impact through increased sharpness.
Had fine grain, at least as good as D-76.
Maintained good film speed.

Sharpness and fine grain problems

Sharpness and fine grain don’t normally go together, as we see of course with D-76. I demonstrated in the FX 1 and FX 2 acutance developer chapters that ultimate sharpness means larger grain although, it has to be re-stated, this was largely mitigated by the higher definition of the final print thus tending to hide the grain from the viewers notice. FX 3 enhanced sharpness too but again, the grain was more noticeable than D-76 because of the reduced sulphite level. So, it seemed back in the 1950s that increasing sharpness will always increase grain. That, at least, was the view of many, if not all, photo-chemists. But Crawley looked at the problem through a different lens and figured out a way to achieve this paradox using a new and novel method. He believed that he could keep the solvent level higher, thus keeping the grain at a similar size to D-76, but use three developing agents. I think he used one to enhance sharpness, one to enhance film speed, and one to re-energize them and keep them going.

It’s well known that phenidone can enhance film speed but is not believed to be as sharp as metol. The reason is that phenidone is better at reducing halide crystals that have had less exposure to light (the toe) but doesn’t react as much as metol to development by-products. With sharp acutance developers such as FX 1 it’s the by-products, such as bromide and iodide, that cause the metol to enhance the feeling of sharpness around high contrast boundaries, explained in detail in the FX 1 article on this blog site. Phenidone just isn’t affected as much by these bromide by-products. So Crawley added both phenidone and metol together. He was onto something here but to maximise the advantage of using these two developing agents together he needed to hit the sweet spot of amounts of each, the overall alkalinity, the amount of solvent, and the delicate amount of restrainer (such as potassium bromide). With FX 4 he didn’t quite hit that sweet spot but a few years later he certainly would with FX 15!

FX 4 1+1 with FP4 Plus EI125 7 minutes Ilford agitation

The hydroquinone could be doing more than regeneration

I might add the hydroquinone is the third developing agent but here it just regenerates both phenidone and metol; so they don’t oxidise and fail. The borax alkalinity is too low for the hydroquinone to do any of the actual halide reduction (development). However, the hydroquinone might be doing something else, assisting in sharpness! You’ll note that the amount of hydroquinone is less than FX 3 and is being shared between both developing agents in FX 4. Could this be helping with sharpness? Could the metol be creating acutance at contrast boundaries because it’s being a little starved of regeneration? I don’t know but it’s worth thinking about, especially as Crawley’s later fine grained acutance developers had even less hydroquinone. I believe this might well have been another of Crawley’s strategies with his solvent developers, finely balancing the hydroquinone to fine tune regeneration and enhance acutance.


Some Crawley Solvent developers	Hydroquinone levels per litre working*	Other developing agents
FX 3	6g	Phenidone
FX 4	5g	Metol, Phenidone
FX 15 Acutol-S	2.25g	Metol, Phenidone
FX 24 Aculux**	1g	Metol, Phenidone

*Full strength working solution

** Uses Potassium thiocyanate as solvent

It should be stated that the alkalinity of FX 15 and FX 24 is higher than FX 3 and 4 and so hydroquinone’s development ability might be activated a little more. However, being at such a reduced amount the hydroquinone will probably also starve the metol and phenidone of regeneration and this will enhance acutance. FX 15, in particular, has improved acutance compared to FX 4.

Note:
D-23 doesn’t use hydroquinone to regenerate the metol but there’s a lot of metol available for reduction of halides. It’s also softer on the highlights because of the metol reacting to bromide by-products from the film.
—-

Compensating highlights and fine grain

FX 4 also has a slight compensating effect that Crawley talked about, useful of course for controlling bright areas such as skies. Can we have a developer that gives fine grain and compensation?

Many developers provide highlight compensation. This is usually achieved through dilution. By increasing dilution one lowers the amount of developing agent available to reduce the silver halides. Therefore, where a lot of developing action is going on, such as in those highlights, the developer slows, developing less, until replaced by agitation. This is how semi-stand or stand development works to reduce contrast and compensate highlights.

Another method, used for compensation, is two bath development. This too uses developer exhaustion in bath B to slow down development in the highlights while keeping it going in the, less exhausted, shadows.

But there’s an unfortunate side effect, specifically with solvent developers. Increasing dilution obviates the fine grain because the solvent concentration (usually sulphite) is now lowered well under an adequate level for silver grain etching and re-plating (the basis of the fine grain effect). This same problem happens both with dilute developers and with two baths.

Let’s look at an example, the solvent developer D-76. At full strength there’s 100g per litre sodium sulphite, a good level for etching and re-plating and the subsequent fine grain. At 1+1 dilution there’s 50g per litre, just above the 45g per litre minimum solvent level that begins the fine grain effect (according to Crawley). Unfortunately, at the 1+1 dilution, there’s little compensation so to get more we are forced to dilute further, to 1+2 or 1+3. By now, at 1+3, our solvent level is a meagre 25g per litre, much too low to maintain the fine grain status of the developer. At this sulphite level, and with such dilute developing agents, D-76 has actually started to become a sort of acutance developer Not, I might add, a well balanced or particularly good one!

So, through dilution we’ve managed to obtain compensation with D-76 but at the cost of fine grain.

Crawley’s FX 4 probably compensates highlights a completely different way and I suspect it’s because of the metol. Without the metol being fully regenerated, and because of the build up of by-products in the high development areas like the sky, I think the metol is running out of steam. This then leaves only the phenidone left and basically retards development and provides compensation. By the time the metol and phenidone has developed the shadows and mid-tones the metol has been slow in the highlights so by personal development time completion there’s some pleasant compensation.

Of course, I don’t know what Crawley was thinking or doing but these theories around his formulations seem quite logical. His pursuing of the three developer combination, metol, phenidone, and hydroquinone, certainly gave his developers some qualities that others just didn’t have. They surpassed the best that the giants like Kodak could produce at the time. Yes, there was some complexity in it but to Crawley it was worth it and for me knowing that his developers were some of the most researched, modern, and most successful in photographic application I’m glad he followed this research in formulation.

FX 4 Formula


Chemical	Amount
Water 50C	800ml
Metol	1.5g
Sodium sulphite Anhyd.	100g
Hydroquinone	5g
Phenidone	0.25g
Borax	2.5g
Potassium bromide	0.5g
Water to make	1 Ltr

The amount of phenidone is the same as FX 3 yet Crawley added 1.5g of metol and reduced hydroquinone a little.
I recommend 1+1 as the best balance for sharpness and grain for cubic grain films (such as FP4).
1+3 recommended for tabular films but test, test, test.

I am providing the most common formula here and the one I tested. At least one time the formula was written with an increase of hydroquinone by a gram, to 6 grams. However, it seems that this formula is the most used and published and the other might have been just a misprint.

FX 3 Left – FX 4 Right
Tonality and Detail

FX 3 Left – FX 4 Right
Sharpness FP4 120 film

Like FX 3 I found the development time was rather brisk, just 7 minutes at a 1+1 dilution using 30 seconds of constant agitation followed by 2 inversions every minute. Unlike FX 3s ISO boost I found the film speed to be box at best. In the past I have used this developer more like D-76 and halved the film speed and it works well like that. The tests I did here were with FP4 at EI125 but shadow detail is wanting even though my film speed test showed that was the speed given. This is a quirk of this developer.

Tonality

The developer tonality is good. Above is a comparison of FX 3 and FX 4.

The tonality comparison, a 100% scan enlargement, demonstrates the similarities of FX 3 and FX 4 in tonality. It also demonstrates some of the compensation with FX 4. Looking between the chimneys one can see that the FX 4 has slightly more micro-contrast and sharpness. To the right of the chimneys the FX 4 has compensated a little. Tonality wise, the FX 4 has better tonality to me, the chimneys looking rounder because of the more subtle gradation. However, these differences are small in 120 film and in a 12 inch square print, held at 10 inches, it’s not really apparent.

Tip
Minimum advised viewing distance for a 12 inch square print is around 30 inches (76cm). At this distance I see no discernible difference between FX 3 and FX 4.

Sharpness

FX 4 is a reasonable sharp solvent developer but not an acutance developer. I saw only very slight signs of acutance Mackie lines. It is a little sharper than FX 3 in FP4 120 film but again, at normal viewing distances any difference would not be visible.

Note: Due to the slower film speed given the FX 4 enlargement above needed a little more gain in the scanner. This accounts for the speckles and lighter shadow areas.

Grain and sharpness comparison with FX 2

FX 2 Left – FX 4 Right
Sharpness compared with FX 2

The above comparison shows the fine grain of FX 4 compared to FX 2, the glycin acutance developer. It also demonstrates the difference in sharpness! FX 2 has a lot more micro-detail and a clear Mackie line along the top of the gate. This only barely shows on the FX 4 negatives.

Although the FX 4 is sharp it’s nowhere near as sharp as FX 2. But at this stage of Crawley’s developer formulations he was still experimenting with obtaining acutance with solvent developers. It would not be until FX 15 that he really obtained it.

Film speed and pushing

I measured the film speed for FP4 as 125 EI, 1/3 stop better than D-76 which only gives me an EI100 with FP4. But having used this developer before I think it likes a little more exposure than that, at least to get the best results for landscapes. If you try it I suggest over-exposing by halving box speed on the meter and reducing development to 6 minutes at 1+1 dilution.

Because of this I don’t think this would be a good candidate for pushing film. I have never tried it, so I could be wrong, but I feel more active developers are better for under exposure and over development, such as FX 3, FX 11, and FX 55.

Capacity

FX 4 with FP4 Plus 35mm 7 minutes Ilford

The developer has very good capacity when used as stock processing no less than 10-12 films per litre. Just add 5% to development time for every film after the first.

35mm comparison

35mm FX 3 Left – 35mm FX 4 Right
Grain and Sharpness 35mm FX 3 and FX 4

I think this is one of the most telling example photographs developed with FX 4. The FX 3, on the left, can be seen with that lovely high-tone contrast (chimney pot) and more general contrast in the stonework but less refined gradation. The FX 4 on the other hand has considerably more tonality and a little bit more sharpness. Grain is similar and quite controlled with both developers.

I looked at these scans for a long time and came to the conclusion that the sharpness and tonality of FX 4 with Ilford FP4 Plus 35mm is quite nice. Yes, I could develop with FX 4 longer to increase contrast to be similar to FX 3 but I think the tonality would still be superior. It’s just a more realistic look to everything. This is a sign, I think, of the synergy of phenidone and metol, together. Crawley knew he was onto something.

Conclusion

I’m very aware that I didn’t like FX 4 when I first tried it many years ago. This is unfortunate because it’s not a bad developer but it just feels like it’s not Crawley’s best. Having tested it thoroughly, just after FX 3, and using some of the same shots from the lighthouse that I took that day, it didn’t really bring any more to my prints than FX 3. In some ways I actually preferred FX 3 for its brighter glowing highlights, its punchier contrast. It’s this punchier contrast that FX 4 actually compensates out a little, perhaps! It’ll be interesting to compare FX 4 to FX 15 and 18 but that’s further down the line.

photography

FX 1 – Crawley’s First Acutance Developer

July 6, 2026 Pictorial Planet 2 Comments

Introduction

In the early 1900s the tool of the professional photographer was large format cameras such as 4×5 inch, 7×5 inch and 10×8 inch. The negatives were often contact printed directly onto paper. This maintained good contrast, tonality, and negated any sign of grain. But these cameras were big, heavy and bulky. Ansel Adams was famous for carrying his large format camera equipment on the back of a donkey (apparently named Mistletoe) up the hills of Yosemite. Everything was heavy, not just the cameras but the big tripods, the lenses and even, back in the darkroom, the enlargers. Photography was not something the average person could partake in easily. Photographers in those days tended to be professionals.

Then came the much handier 120 sized film, introduced in 1901. It was approximately 61 mm wide. It made slow inroads into the photographic world and became particularly popular with press photographers and the new photographic amateurs who saw it as a way into this interesting hobby. 120 was a wonderful size because of its light-weight, portability with smaller cameras, and its “multiple frames on one film” ability. On a single roll of film you could make several photographs. This was a huge jump in usability.

The booming film industry was of course using black and white film too. Cinematographers and directors were happy using 70 mm wide film strips in the late 1800’s but then, by the 1900s, they too started looking for a more portable and cost saving format. In 1909 they chose a new film size of 35 mm. The size was easy to come by. 70mm movie film could be sliced down the middle and stuck it together therefore doubling the film length and halving the cost per minute for movie makers. Perforations were made on both edges of the film to allow easy projection.

For 35mm stills photography, photographers had been using various cameras since 1905! But Leitz started making their famous Leica cameras in 1925 and released the first ever system camera, the Leica 2 (interchangeable lens system) in 1932. This was another breakthrough in usefulness. Small, portable cameras with easily changed lenses.
But by far most photographers used large format with a few medium format. The popularity of 35mm must have started to grow though because Kodak decided, in 1934, to release their first 35mm film to the public; what they called the miniature “135” size film. D-76 was recommended as the developer of choice probably because this was the Kodak developer used by the 35mm film industry. D-76 was a good developer which minimised grain whilst maintaining decent film speed. Many companies made variants of D-76 for their film development and it became the de facto standard.

The problem

But film manufacturing companies such as Ilford, Kodak, and Adox had realised there was a problem. They saw that when they coated the small 35mm film with the same photographic emulsions used on their large or medium format films, print enlargements were grainy and sharpness was poor. This lack of sharpness and contrast was due to the bigger enlargement requirements of such a small format. The lack of sharpness and contrast was compounded by photographers using the recommended fine grain solvent developers such as D-76, D-23, and D-25. All these developers were good at reducing the natural grain of the film but lacked sharpness and, especially lacked fine detail. When the 35mm negative was enlarged fine detail was rendered poorly.

The only way it seemed, to get sharp, impactful, detailed prints, was to use large format negatives and therefore low enlargement, or no enlargement at all by contact printing.

Emulsions improve in sharpness

However, emulsions were slowly improving. With the growing popularity of 35mm photography, especially after WW2, new updated film emulsions had to be designed with the smaller negative and bigger enlargement factors in mind. The emulsion designers did good work and not only managed to reduce grain in new films but also reduced emulsion thickness and added more silver creating what Crawley called “compact emulsions”, meaning thin and high in silver halide content. This helped to improve the sharpness of the negatives and of enlargements, the thinner emulsion creating less diffusion of light passing through it and the rich silver content creating bolder contrast lines when enlarged and improved tonality. Ilford was one of the first companies to manufacture thinner, sharper emulsions with their PanF and Adox too was doing the same in the 1950’s. But as far as film developers were concerned there were few designed for the small (called miniature) format. The 1930’s Beutler developer stood out. It is said it was designed for 35mm film and many serious 35mm photographers started using it. It was a sharper compensating developer than the solvent types.

Crawley’s research

By the early 1960’s Geoffrey Crawley started publishing his research on developer formulation and intrinsic sharpness and how the impact of 35mm negative enlargements could be improved.

Crawley used four terms in his writing:

Acutance. A scientifically measurable quantity, directly correlating to the measurement of density gradients.
Resolving-power. How well a lens, film, or developer (or all three!) reveals detail. It’s something you can actually scientifically measure with a resolution chart.
Sharpness. Crawley said sharpness is a perception and is typically assessed from a normal viewing distance relative to image size. At the micro-level it can be measured by acutance. Crawley said “When acutance is high, sharpness is good.”
Definition. Unlike sharpness which is judged at normal viewing distance, definition is judged up close to the photograph – it is a measure of how clearly fine details can be seen. Crawley said “When the acutance with which fine detail is rendered is high, then definition will be pronounced good.”

We might notice something about the way these four attributes can combine. That is, the sharpness of the photograph might be good at a normal viewing distance, even if the resolution is poor i.e. there’s little or no fine detail. This is because acutance can improve sharpness on a macro level even if there is no detail on a micro level due to a poorer lens, for instance.

Crawley thought that developer formulators, up to that point, had mostly been concentrating on, what he called, the grain-speed interlock – minimising grain whilst maintaining good film speed. He decided that a third attribute of the negative should be taken into account, acutance. He formulated and judged his own developers with the grain-speed-acutance interlock in mind.

It was clear to Crawley that by increasing acutance there was an increase in grain, as compared to D-76, but he also noticed a psychological effect.
Grain

This psychological effect is important to photographers. What Crawley found was that if definition is good (i.e. there is good fine detail rendered by the lens) and acutance is high because of the developer then the increase in grain is masked by that detail.

Cave and Pebbles. FX 1 with FP4 Plus 120 square format

Take a look at any photograph that shows a lot of detail. You won’t see much perceivable grain in that image. Now take a look at either a large out of focus area or an expanse of plain sky. You will now see grain because the brain is not giving its attention to detail anymore. As Crawley stated, “The grain in a sharp image is much less obtrusive than in a soft image. In every photographically produced picture, there are really two images, the intended image of the subject, and a secondary grain image; if attention is riveted to the primary image of the subject, the less the grain image obtrudes.”

Crawley knew then that increased grain was not such an issue as previously thought.

Grain of photograph above at 100% enlargement. Note the acutance Mackie line between the edge of the pebbles and the sea.

My first use of Crawley developers

In those days, in the early 70’s, I had never heard of Geoffrey Crawley, or read his writing from the early 60’s, some ten years before. But, even as such a young photographer I could clearly see this effect in my own work. I had started developing in my father’s D23 Replenished and for many years was perfectly happy with the results. When I had a good lens I felt my photographs were sharp although I did realise that detail seemed to be lacking. This lack of detail was unsatisfactory to me. Then someone told me to try Crawley’s Acutol. It was sold by a company called Paterson. “What difference would a developer make?”, I thought. But it did.

Acutol actually made a huge difference. I was amazed at the detail and sharpness of the results. What I thought had been sharp photographs were not. Acutol took sharpness to a new level. What was it that made such a difference? What was so special about this developer? The answer was simple enough. The new developer was an acutance developer and acutance now became my new best friend.

This was how many people became aware of Crawley’s work with developers, Acutol, and the Paterson ACU range of chemistry.
And so Crawley became famous for his acutance developers. He also released formulas for solvent developers, which I’ll cover later, and even a monobath. But his initial fame came from FX 1 and his other FX developers. And FX 1 was his “high acutance” and “sharpness first” formula. Let’s take a look at it.

FX 1 Formula

I start by showing the working solution (concentrate shown below).

FX 1 Working solution:

Chemical	Amount	Use
Metol	0.5g	Developing agent
Sodium sulphite	5g	Preservative
Sodium carbonate Anhyd.	2.5g	Accelerator
Potassium iodide 0.001% soln.	5ml	Homeopathic amount of restrainer
Water to make	1 Ltr

Best used with slow to medium speed films.
For starting development times try 12 minutes and adjust from there.
Use best technique for making the sharpest possible photographs. Any poor technique might be amplified by this sharp developer.

Notes on formulation:

Crawley followed Willi Beutler’s idea that in order to get good acutance one needed a strong alkali.

Up to this point many common film developers, such as the ubiquitous D-76, used Borax (PH 9.2) as the accelerator. This is relatively mildly alkaline and delivers a slow, steady, controlled development of the film, allowing more control over the developing highlights. Sodium carbonate (PH 11.5), used in this formula, is much more alkaline. It’s normally used in paper developers where development speed is quick and where we develop towards completion it is a contrasty accelerator that can easily blow out highlights with metol. Used with a ‘normal’ amount of metol the strong alkalinity of sodium carbonate would provide too much energy to metol and the negative highlights would quickly burn out, even before the shadow development was complete! This is seen in the Beutler formula where contrast could be an issue.

Crawley says that photographers of the time knew Beutler was too contrasty and chose to half the amount of sodium carbonate. He chose to do the same in FX 1.
Developing agent reduction.

But Crawley wanted to increase the acutance even more than Beutler, after all, this was a sharpness-first developer. He understood that the Eberhard effect, the effect that caused Mackie (or acutance) lines, was caused by the reduced activity of developing agent on one side of a contrast boundary as compared to the activity on the other side and the subsequent transmission of developing agent and bromide restrainer across the contrast boundary within the emulsion. If he could just enhance this effect he would have more acutance and a sharper developer. So he reduced the amount of developing agent by a half.

This was a small amount of developing agent now. As an example, D-76 uses 2g of metol as developing agent in the working solution and FX 1 uses only a 1/4 of that amount¹.
Compensation

By Crawley reducing the amount of metol to 0.5g/Ltr he ensured that, between agitations, the developing agent would slow down quickly where it was working hard in the highlights, yet let the shadows continue to develop. Therefore there was some compensation to reduce excessive contrast.

Acutance

But local acutance was also increased. Bromide is a byproduct of development and the developing agent, metol is effected strongly by it. When the bromide permeates across the contrast boundary of a sharp line or fine detail it quickly stops the small concentration of metol next to that boundary causing a light line to form. You might see these light lines in your photographs, especially on horizons when using acutance developers like diluted Rodinal.
Potassium iodide restrainer.

The trace amount of potassium iodide is very interesting. Potassium iodide is a restrainer like potassium bromide. Crawley believed that with certain, slow films the iodide helped improve acutance at the micro-contrast level i.e. the fine surface detail. He thought it should only be added if the photographer was using the highest quality lens and best possible skill to reduce any chance of camera shake (high shutter speed, tripod, etc). Because of the addition of iodide in modern films it’s probably not going to make a difference with all films these days so I recommend testing with and without this addition and assess it’s use².
The two reasons for the low levels of sulphite

The sulphite level was carefully formulated for two reasons. The first reason was for film speed. It was known already that sulphite affected the speed of the film³. The sulphite etched away at halide crystals revealing deep latent development sites. These sites would not normally have been developed but the etching revealed them to the developing agent. Unfortunately, at high levels, sulphite’s physical development was a problem. At higher levels sulphite encouraged halide crystals that had not been exposed to light to develop! Fog! Thus restrainers had to be used to counter this effect and reduce physical development fog. So the sulphite had to be kept low. Film speed is improved up to 100%. I tested FP4 Plus and saw an EI of 200 ( 66%). With PANF Plus I saw an EI of 100 ( 100%).

The second reason for the low amount of sulphite was acutance. Crawley believed sulphite regenerated metol. He said, “To prevent regeneration of the developing agency [sic] sufficiently to improve definition, the concentration of sodium sulphite anhydrous must be kept below 6g/Ltr.” But he stated that below 4g per litre the keeping properties of the developer were seriously affected. By preventing the regeneration of metol he again increased the acutance in those areas where the Eberhard effect manifested.

FX 1 was derived from the Beutler developer. Here is the Beutler formula:

Beutler formula:

Chemical	Amount
Metol	1g
Sodium sulphite	5g
Sodium carbonate	5g
Water to	1 Ltr

Crawley found this to be too contrasty with modern films. Users of this developer developed with it at half strength where it becomes similar to FX 1 without the iodide. But, and this is a big but, at half strength the sulphite level was too low, according to Crawley, to maximise film speed.

FX 1 Formula Concentrated solution:

In order to keep well this concentrate is made up in three parts, A, B and C.

FX 1 Concentrate Part A

Chemical	Amount
Water 50c	800ml
Metol	5g
Sodium sulphite	50g
Water to make	1 Ltr

FX 1 Concentrate Part B

Chemical	Amount
Water	800ml
Sodium carbonate Anhyd.	25g
Water to make	1 Ltr

FX 1 Concentrate Part C – Iodide solution

Chemical
Potassium iodide 0.001% soln.

Use at dilution: 1A+1B+8 Water

Add part C to working developer as follows:
30ml A 30ml B made to 300ml with water then add 1.5ml iodide soln.
50ml A 50ml B made to 500ml with water add 2.5ml Iodide soln.

This concentrate should keep well (at least 6 months in sealed bottle).

Developing with FX 1

I use FX 1 to develop films as follows:

An initial 30 seconds gentle agitation with a slight twisting action.
Then 5 seconds agitation (two inversions) every minute.
Start with a time of 12 minutes and adjust.
Reduced agitation increases sharpness even more:
- Agitate for the first 30 seconds.
- Agitate every two or three minutes.
- Increase development time by 50%.

FX 1 Developer Uses
Landscape 35mm	Yes
Landscape 120	Yes
Portrait 35mm or 120	No

Tip – Making Potassium iodide 0.001%
the Crawley way!

Take 1g iodide and dissolve in 1 Ltr warm water. Stir for 2 mins and let stand for 3 mins. Makes 0.1% solution.
Take 100ml of this solution and make up to 1 Ltr with water. Stir 2 for mins and stand for 3 mins. Makes 0.01% solution.
Take 100ml of this solution and make up to 1 Ltr with water. Stir 2 mins and stand for 3 mins.

That’s your 0.001% solution!

FX 1 with FP4 Plus in 35mm. Pentax MX with 50mm F1.4 lens. Full frame shown.

FX 1 with FP4 Plus in 35mm. Pentax MX with 50mm F1.4 lens. 100% enlargement of scan showing grain.

FX18 with FP4 Plus in 35mm. Pentax MX with 50mm F1.4 lens. 100% enlargement of scan showing grain comparison.

This is the amount of metol in D-76 at 1 3 dilution, a dilution that is used to increase sharpness! Unfortunately for the D-76 users the sulphite levels are still too high for good acutance and alkalinity also too low. There is a much sharper D-76 type developer that will be shown later. ↩︎
Crawley thought PANF would give the best adjacency effects if used with an orange or red filter. ↩︎
Below 2.5g/Ltr any film speed gain is lost and film speed returns to normal ↩︎

photography

Crawley’s FX 3 – Solvent developer and great all-rounder.

May 19, 2026 Pictorial Planet 3 Comments

Introduction

What we would call “modern” solvent developers actually began life in the late 1920s, early 1930s as medium format and 35mm film sizes became popular with photographers. For example, D-76, the accepted standard for solvent developers, was formulated in 1927. Many others were subsequently designed, some with better speed, some with finer grain, all with varying degrees success but D-76 (also known as ID-11) has remained the developer that all others are judged against.

It’s interesting to understand the reason these developers are called solvent developers. Through their use of chemicals they dissolve, or eat away some of the silver in the image and subsequently reduce apparent grain.

Typically, these type developers use silver solvents such as:

Thiocyanates
Thiosulphates
Sulphites

(This list ranks solvents from most powerful to least powerful.)

Kodak’s DK-20, for instance, is a very fine grain solvent developer and uses two solvent chemicals thiocyanate and sulphite to reduce film grain. This is a powerful grain reducing duo but with modern thin emulsion films this powerful solvent developer can cause dichroic fog (see tip below).

Covesea Lighthouse, Lossiemouth, Moray, Scotland –
FX 3 1+1 FP4 Plus EI160 6 minutes Ilford agitation 20C. Rollei SL66

Tip – Removing Dichroic Fog

Dichroic fog is a very fine film fog made from tiny silver particles precipitated on the surface of the emulsion. This fog reflects with colours of the spectrum when inspected giving it the name dichroic. It can be formed by solvent developers, especially if they have been re-used and are carrying a lot of dissolved silver. A short soak in a 2% acetic (vinegar) acid solution, such as fresh stop bath, can sometimes remove it.

Nowadays, sulphite alone is most often used as the solvent for fine grain developers. Sulphite is milder in action and at normal solvent concentrations of up to 100g to 125g per litre rarely creates dichroic fog issues with most films.

When formulating his early FX developers, Crawley did extensive research on sulphite levels. This research showed that the solvent action of sulphite begins around the 45g per litre concentration. Below that level there is little dissolving and re-plating action but above 45g/ltr the solvent (and therefore grain reducing action) slowly increased.

Tip – Solvent developers might reduce grain through two avenues:

High sulphite levels, above 45g/ltr introduces “physical development” on top of chemical development. Physical development is where the sulphite dissolves the edges of the developing silver grains and then re-plates (or places) that dissolved silver elsewhere on the negative, on other silver halide crystals that either should not be developed at all or who’s latent potential to be reduced to silver is so deep they would not have normally been developed. This addition of a microscopic re-plated silver grain then encourages their development.
Sulphite also seems to reduce grain clumping, the primary cause for the appearance larger grain in negatives. Clumping is the buildup of developed silver around a seeded halide crystal. This is a form of infectious development where the action of developing one seeded site spreads to nearby halide crystals. Crawley said that with simultaneous chemical (regular) development and physical (sulphite) development a balance seems to form that reduces this clumping. A low alkalinity accelerator also helps to avoid clumping, he said, by providing conditions for slower, even development. This would explain why a developer like Rodinal has larger observable grain – the high alkalinity causing clumping.

It’s well known that Kodak’s D-76 became the standard for solvent developers; all others are compared to it. Companies either copied it or made small modifications in an attempt to improve on the formula (for instance Adox MQ Borax). To Crawley, the D-76 formula was the most successful of developers in balancing, what he called, the speed-grain interlock. In Crawley’s opinion D-76 achieved the best balance between EI (film speed) and granularity for a film.

However, Crawley did not believe D-76 produced the most impactful and sharp prints from smaller formats. Consequently, he incorporated sharpness and micro-detail into his assessment of development qualities and termed it the speed-grain-acutance interlock. By changing his developer formulation objective, that is to finding chemistry that improved the three-way interlock of speed-grain-acutance, Crawley knew he could improve upon D-76 and give photographers the tools they needed to make more impactful prints. These ideas of Crawley’s, in the 50s and 60s, were industry leading and later encouraged companies to examine better ways to manufacture films and formulate developers, with an eye on the impact of the final print.

FX 3 is Crawley’s first solvent developer. It seems he wanted to formulate a phenidone version of Adox MQ Borax, a sharper, fine grained developer of the D-76 type and popular with photographers of the time. Having used MQ Borax myself in the past, I believe Crawley not only formulated a good phenidone version but has improved upon it. I prefer the grain, the sharpness is at least as good, and I like very much the improved tonality.

Of all of Crawley’s solvent developers FX 3 has the least solvent effect with only 75g of sodium sulphite per litre stock. This reduces some of the solvent re-plating action (increasing perceived grain) but makes it sharper. But the carefully balanced formula provides attractive, buttery smooth tonality, definitely enhanced compared to his earlier acutance developers.

Note:

When FX 3 is diluted 1+1, my preferred dilutions for landscape work with solvent developers, the working solution has less than the 45g/Ltr of sulphite. This amount is below the specific amount where, Crawley stated, physical development (re-plating) begins¹. Therefore, at 1+1 dilution you are getting the grain inherent in the film and better sharpness because of no re-plating action.

It’s tonality that is the real headline with this developer

FX 3 is a lovely developer to use. It provides a smoothness of tone, a richness in gradation, that can deliver a three-dimensional look. This and the boost in sharpness from the lowered sulphite, both stock (compared to D-76) and diluted, helps parts of the image to stand out against the background. This could be very useful in portraiture where the subject often needs a softer tonality than acutance developers provide. Also, using the developer at full strength will reduce grain and smooth the skin ².

This does come at a small price though. FX 3 is a hot developer and can easily cook the highlights of your photograph unless kept fully under control with tight, well practiced procedures. However, with good technique this is easy enough for the darkroom worker or serious film scanner to overcome and, as with all things film photography, the results will reward the conscientious photographer.

The tonality and detail in the highlights is remarkable with this developer. Covesea Lighthouse, Lossiemouth, Moray, Scotland – FX 3 1+1
FP4 Plus EI160 6 minutes Ilford agitation 20C. Rollei SL66.

FX 3 Formula

The FX 3 formula is primarily designed to be a fine grain, general purpose developer specifically formulated for smoother, wider tone and finer grain than FX 1 and FX 2. Although a solvent developer sharpness has been reinforced through reduced sulphite levels.

The developer is ideal for both portraits and landscapes at 1+1 dilution where it provides strong contrast, good sharpness, and a pleasant, long tonal range. However, it does not provide acutance and, because of this, micro-detail is not as well supported.

This developer is suitable for fast films in 35mm or medium and slow films where greater enlargement is required.

A word of caution. FX 3 developer increases contrast quickly when developing so careful personal development time testing is essential to get the best and not cook the highlights. It’s very easy to over develop with FX 3 and I suspect many photographers have inadvertently done so in the past denying them of this developer’s gorgeous highlights!

I found my development time, for FP4 Plus shot at a measured film speed of EI 160, diluted 1+1 with water, was a rather brisk 6 minutes using Ilford agitation. Crawley stated a development time should be around 10% less than D-76 but I found it to be much shorter than that (as we will also find in FX 4). Don’t be surprised if you find your development times to be somewhat shorter than expected. Like all developers aim for grade 2 prints with medium format and grade 3 with 35mm.

Film speed and pushing

In the usual Crawley manner, there is a slight speed gain above box and I found an EI of 160 was delivered with FP4 Plus film for normal contrast (grade 2) with 120 film.

This would make a good pushing developer with nice, short development times. As I mentioned above, it proved itself rather active, and I suspect N development would be easy and produce good pictorial quality negatives, especially with the attractive highlights FX 3 can produce. It would be an interesting comparison for the pushing work we did a few weeks ago.