Pictorial Planet
Barry Thornton's
diXACTOL UltraTM
Please order diXACTOL Ultra in my shop or email me if your country is not in the database for postage.
diXACTOL UltraTM is a pyro (catechol) tanning and staining developer formulated by the late Barry Thornton. It was his second developer of the diXACTOL range being a much improved formula over the first diXACTOL and adding the word "Ultra" to the name to show this lineage. It provides very sharp negatives and high stain and long tonality.
diXACTOL UltraTM is a pyro (catechol) tanning and staining developer formulated by the late Barry Thornton. It was his second developer of the diXACTOL range being a much improved formula over the first diXACTOL and adding the word "Ultra" to the name to show this lineage. It provides very sharp negatives and high stain and long tonality.
Negatives that would be impossible with conventional developers print with fine graduation and much less struggle in burning and dodging.
Barry Thornton
The main improvements to the developer were a boost in film speed to around box or 1/3 stop under box improving shadow detail and also an increase in beneficial staining over other pyro developers. It still maintained its signature sharpness, giving an almost 3d look, and good contrast but the tonality, for me, was also improved with longer and richer tones.
Formulated initially as a 2-bath developer the instructions later added its use as a single bath. This is because, as a 2-bath some people suffered from uneven development especially around the edges of the film that touched the developer reel. This, Thornton said, was due to contamination of the developing reels with previous chemicals and/or the local water supply. Using the developer with a new reel (unused with other developers) helps and using the developer as a single bath alleviates the problem completely.
Formulated initially as a 2-bath developer the instructions later added its use as a single bath. This is because, as a 2-bath some people suffered from uneven development especially around the edges of the film that touched the developer reel. This, Thornton said, was due to contamination of the developing reels with previous chemicals and/or the local water supply. Using the developer with a new reel (unused with other developers) helps and using the developer as a single bath alleviates the problem completely.
Thornton later recommended single bath development with semi-stand, reducing agitation to every 2 minutes while extending development time by around 10%. This he said gave results at least as good or even better than the 2-bath.
Thornton formulated the pyro developer with pyrocatechin because of the stain colour and the tanning. He'd used PMK, a pyrogallol based developer and although he liked it found the highlights, especially on multigrade paper, lost contrast. He remarked it was like printing the highlights with a softer grade filter. This is because pyrogallol gives a more yellow stain, the same colour as the soft grade filter with multigrade papers. This soft filter effect was more in the highlights because that's where most of the yellow/green stain with pyrogallol is formed.
He knew of a different form of pyro, called pyrocatechin, from his career in newspaper printing, and knew that pyrocatechin gave the most tanning of any developing agent.
He also said the stain colour on negatives made with pyrocatechin was mainly brown with only a hint of yellow/green. This was advantageous in the darkroom with VC papers, as compared to pyrogallol, because the brown was a similar colour to VC paper safelights therefore creating an advantageous masking effect in the highlights not the soft grade filter effect like the yellow colour of pyrogallol processed negatives.
diXACTOL Ultra is a very versatile developer because there are three main methods of developing with this formula. 2-bath development, for those that want great negatives using the simplest technique or for processing different films together at the same time. There's single bath development which is great for zone system workers like me. And there's the technique Barry recommended, single bath semi-stand development which gives some compensation like the 2-bath method. This final method helps against uneven development that some users have seen the using the 2-bath method (see bottom of page).
2-bath development was originally recommended at 24C but later revised down to 21C. Frankly, in my experience, anywhere between 20C and 24C should work well with only slight development time adjustments - if necessary at all. The time in each bath, Thornton said, can be anywhere between 3 1/2 and 6 1/2 minutes, depending of the grade of paper you want to print at. Longer development, lower grade. I personally find 5 minutes in each bath is a good 'standard' time but experiment to find what you prefer.
When using diXACTOL Ultra as a 2-bath it's important not to contaminate the baths with each other. diXACTOL Ultra is a true divided developer so no development at all takes place in bath A, the A solution just defuses into and throughout the film emulsion. It is when A is poured out and B poured in that development begins.
Always dilute the developer with deionised or distilled water.
After diluting your two baths you should have two beakers, one with the appropriate amount of Bath A and one with the appropriate amount of Bath B. I keep these apart on my work surface to protect against splashing one to the other.
Prepare your water rinse stop bath or, even better, alkaline stop bath (available here in shop) and alkaline fix all at the same temperature as the developer (or within a degree).
Unusually for a 2-bath, Thornton recommends one or more pre-washes of the film with water at developer temperature. This is to bring the film and tank up to the temperature of the developer and washes out any anti-halation dye in the film, particularly 120 film. As I see it, especially because this is a divided developer, any very slight dilution of the A bath, by remnants of the pre-wash, should not make a noticeable difference in development compared to not using a pre-wash.
Pour out the pre-wash and pour in bath A.
Agitate once and rap the bottom of the tank to dislodge any air bubbles sticking to the film, then continue agitation for a total of 30 seconds, rap tank again. This can be done with either inversion agitation or swizzle stick.
Now agitate by two inversions (or 5 seconds twizzling) every 30 seconds for the remainder of the time, rapping the tank after each set of agitations.
At the development time, pour out bath A and keep if re-using and immediately pour in bath B - no rinse between.
Agitate once and rap the bottom of the tank. Leave to stand, undisturbed, for 30 seconds.
Each 30 seconds agitate by inverting once (or 5 seconds twizzling), rap the tank and leave to stand, undisturbed, for 30 seconds.
At the completion of development time, empty the tank of B and keep if re-using the developer. It's normal for it to be dark purple-brown (if not something is wrong). Then stop development either by using an alkaline stop bath or at least three rinses of water (ten inversions per rinse). Some photographers use a half strength acid stop also at this point but I personally like to keep the process alkaline and use either the new alkaline stop or water rinses as described.
Now fix the film with alkaline fix (again because I like to keep the process alkaline to protect, as best I can, the stain)
After fixing, wash the film as normal.
If you've used an acid fix but still want to maximise tanning and staining, wash the film using alkalised water. Thornton recommended adding a small amount of sodium carbonate (1 heaped teaspoon per 5 litres) to make it alkaline. This, he said, would assist maximum stain formation and tanning after an acid fixer. Make sure the chemical is fully dissolved in the water before using it to wash the film. For your final wash, and before rinse aid, use pure water for a couple of thorough rinses.
Sodium bicarbonate can also be used but just 1/3 to 3/4 a teaspoon per 5 Ltrs - again, make sure it's fully dissolved and again do a couple of good post wash rinses before rinse aid.
Finally, use your rinse aid per the instructions and hang in a dust free area to dry.
The A bath and B bath can be re-used for 4 hours at least, with no change in development time for each bath. The capacity of the A and B bath is at least 3 films of 35mm or 120, or equivalent.
- I personally use a developing reel dedicated to Dixactol Ultra and do not have the issue with two bath.
- For zone system work I use it as a single bath with regular (1 minute) agitation. I find, because of diXACTOL's high tanning (hardening of the emulsion by the pyrocatechin), this developer makes beautiful, crisp, high acutance negatives with normal single bath development.
- I rarely use minimal agitation finding that the 2-bath and regular development gives superb negatives of great sharpness and lovely tonality.
Pyro Developers: Pyrocatechin vs. Pyrogallol
Thornton formulated the pyro developer with pyrocatechin because of the stain colour and the tanning. He'd used PMK, a pyrogallol based developer and although he liked it found the highlights, especially on multigrade paper, lost contrast. He remarked it was like printing the highlights with a softer grade filter. This is because pyrogallol gives a more yellow stain, the same colour as the soft grade filter with multigrade papers. This soft filter effect was more in the highlights because that's where most of the yellow/green stain with pyrogallol is formed.
He knew of a different form of pyro, called pyrocatechin, from his career in newspaper printing, and knew that pyrocatechin gave the most tanning of any developing agent.
He also said the stain colour on negatives made with pyrocatechin was mainly brown with only a hint of yellow/green. This was advantageous in the darkroom with VC papers, as compared to pyrogallol, because the brown was a similar colour to VC paper safelights therefore creating an advantageous masking effect in the highlights not the soft grade filter effect like the yellow colour of pyrogallol processed negatives.
Developing with diXACTOL Ultra
diXACTOL Ultra is a very versatile developer because there are three main methods of developing with this formula. 2-bath development, for those that want great negatives using the simplest technique or for processing different films together at the same time. There's single bath development which is great for zone system workers like me. And there's the technique Barry recommended, single bath semi-stand development which gives some compensation like the 2-bath method. This final method helps against uneven development that some users have seen the using the 2-bath method (see bottom of page).
2-Bath Development - 1+19
2-bath development was originally recommended at 24C but later revised down to 21C. Frankly, in my experience, anywhere between 20C and 24C should work well with only slight development time adjustments - if necessary at all. The time in each bath, Thornton said, can be anywhere between 3 1/2 and 6 1/2 minutes, depending of the grade of paper you want to print at. Longer development, lower grade. I personally find 5 minutes in each bath is a good 'standard' time but experiment to find what you prefer.
When using diXACTOL Ultra as a 2-bath it's important not to contaminate the baths with each other. diXACTOL Ultra is a true divided developer so no development at all takes place in bath A, the A solution just defuses into and throughout the film emulsion. It is when A is poured out and B poured in that development begins.
Always dilute the developer with deionised or distilled water.
- Thornton's instructions describe dilution for the separate two baths A and B as 1+19 so
- 15ml to 285ml for a 300ml film tank or
- 25ml + 475ml for a 500ml tank.
- My personal preference, as you've probably seen on my YouTube channel, is to use a little more developer volume than that. This combats uneven development such as air bells. So I make my two baths A and B from 20ml to 380ml water making 400ml volume for 35mm developing tanks and 30ml to 570ml water making 600ml total volume for 120 film tanks.
After diluting your two baths you should have two beakers, one with the appropriate amount of Bath A and one with the appropriate amount of Bath B. I keep these apart on my work surface to protect against splashing one to the other.
Prepare your water rinse stop bath or, even better, alkaline stop bath (available here in shop) and alkaline fix all at the same temperature as the developer (or within a degree).
Unusually for a 2-bath, Thornton recommends one or more pre-washes of the film with water at developer temperature. This is to bring the film and tank up to the temperature of the developer and washes out any anti-halation dye in the film, particularly 120 film. As I see it, especially because this is a divided developer, any very slight dilution of the A bath, by remnants of the pre-wash, should not make a noticeable difference in development compared to not using a pre-wash.
Pour out the pre-wash and pour in bath A.
Agitate once and rap the bottom of the tank to dislodge any air bubbles sticking to the film, then continue agitation for a total of 30 seconds, rap tank again. This can be done with either inversion agitation or swizzle stick.
Now agitate by two inversions (or 5 seconds twizzling) every 30 seconds for the remainder of the time, rapping the tank after each set of agitations.
At the development time, pour out bath A and keep if re-using and immediately pour in bath B - no rinse between.
Agitate once and rap the bottom of the tank. Leave to stand, undisturbed, for 30 seconds.
Each 30 seconds agitate by inverting once (or 5 seconds twizzling), rap the tank and leave to stand, undisturbed, for 30 seconds.
At the completion of development time, empty the tank of B and keep if re-using the developer. It's normal for it to be dark purple-brown (if not something is wrong). Then stop development either by using an alkaline stop bath or at least three rinses of water (ten inversions per rinse). Some photographers use a half strength acid stop also at this point but I personally like to keep the process alkaline and use either the new alkaline stop or water rinses as described.
Now fix the film with alkaline fix (again because I like to keep the process alkaline to protect, as best I can, the stain)
After fixing, wash the film as normal.
If you've used an acid fix but still want to maximise tanning and staining, wash the film using alkalised water. Thornton recommended adding a small amount of sodium carbonate (1 heaped teaspoon per 5 litres) to make it alkaline. This, he said, would assist maximum stain formation and tanning after an acid fixer. Make sure the chemical is fully dissolved in the water before using it to wash the film. For your final wash, and before rinse aid, use pure water for a couple of thorough rinses.
Sodium bicarbonate can also be used but just 1/3 to 3/4 a teaspoon per 5 Ltrs - again, make sure it's fully dissolved and again do a couple of good post wash rinses before rinse aid.
Finally, use your rinse aid per the instructions and hang in a dust free area to dry.
Re-using 2-bath developer
The A bath and B bath can be re-used for 4 hours at least, with no change in development time for each bath. The capacity of the A and B bath is at least 3 films of 35mm or 120, or equivalent.
I already tried it with Fp4+ (120 format). The negatives came out perfectly. I have used exactol in the past but with dixactol … i am really astonished … the detail and sharpness of the negatives.
Dirk Van Damme, Belgium
Zone System With 2-Bath Development
Zone System photographers need to control the contrast of their negatives. This is usually achieved through adjusting development time to increase or decrease highlight values. But time is not a good control with 2-bath developers since the developing agents contained in the A bath are saturated into the emulsion are virtually used to exhaustion during the immersion in Bath B. The bottom line, extension of time does not work well. Reducing times conversely leads to inconveniently short duration and the risk of unevenness. The best method, Thornton said, is to vary the dilution while retaining the N time you have found to be right for your equipment. You should conduct tests. For N-1 conduct trials at 1+24 dilution for both baths. For N+1, start trials at 1+9 dilution for Bath A, and 1+14 Bath B.
Note: Do not use Bath B stronger than 1+14 or streaking, fogging, and negative unevenness is very likely.
I have to say the negs are printing beautifully and the front to back sharpness on the FS3 is astonishing […] So Dixactol will be my go to developer from now on.
A.B.
We now recommend single bath partial stand development as standard.
Barry Thornton
Single Bath Development - 1+7+300
A good starting time for single bath development is between 7 and 9 minutes. Adjust your development for your zone system or personal taste. For instance, my personal time for FP4+ is 7.5 minutes which works well with my enlarger and Ilford multigrade paper.
Single bath development, according to the present day instructions, is carried out at 21C with a dilution of 1+7+300 or pro rata for other capacities.
Note: Only add the B component just before beginning development and stir well.
Begin the development cycle with a pre-wash again at the developer temperature.
Pour out the pre-wash and pour in the developer.
Agitate for one minute and then rap the tank.
Agitate every following minute, rapping the tank after each set of agitations. I invert three times in a ten second period with a slight twist to the tank as I invert.
At the end of the development time empty out the developer - this cannot be reused. It's normal for the solution to have turned a dark purple-brown colour.
Now stop with either 3 water baths of 10 inversions each or by using alkaline stop.
Fix with alkaline fix for twice the clearing time. For our Alkali-Fix that would be 1.5 minutes to clear so a total of 3 minutes when fresh.
Wash using the Ilford wash method.
If you've used an acid fix but still want to maximise tanning and staining, wash the film using alkalised water. Thornton recommended adding a small amount of sodium carbonate (1 heaped teaspoon per 5 litres) to make it alkaline. This, he said, would assist maximum stain formation and tanning after an acid fixer. Make sure the chemical is fully dissolved in the water before using it to wash the film and for a final wash, before rinse aid, use pure water for a couple of thorough rinses. Sodium bicarbonate can also be used but just 1/3 to 3/4 a teaspoon per 5 Ltrs - again, make sure it's fully dissolved and do a couple of good post wash rinses before rinse aid.
Finally, use your rinse aid per the instructions.
- This is the best method of using diXACTOL Ultra as a zone system developer. It allows maximum control of negative highlight density. Because of the high tanning of the emulsion during development this single bath development method also makes negatives of bitingly sharp character due to very good acutance of diXACTOL Ultra.
Recommended Single Bath Development with Semi-stand - 1+7+300
A good starting time for this single bath semi-stand development is 10 minutes. Adjust your development time from there.
- This, Thornton said, is the preferred method of development giving similar acutance to the 2-bath and similar compensation. It alleviates the chance of uneven development that some people have with the 2-bath method.
Single bath semi-stand development, is also carried out at 21C with a dilution of 1+7+300 or pro rata for other capacities. You might prefer 24C if you want to keep development times down.
Note: Only add the B component just before beginning development and stir well.
Begin the development cycle with a pre-wash again at the developer temperature.
Pour out the pre-wash and pour in the developer.
Agitate for 60 seconds and then rap the tank.
Agitate every 2 minutes, rapping the tank after each set of agitations. I invert three times in a 10 second period with a slight twist to the tank as I invert. This two minutes can be extended but beware of uneven development if there's too long between agitation.
Using semi-stand agitation extends regular development time by around 10% but do carry out your development time testing.
At the end of the development time empty out the developer - this cannot be reused. It's normal for the solution to have turned a dark purple-brown colour.
Now stop with either 3 water baths of 10 inversions each or by using alkaline stop.
Fix with alkaline fix for twice the clearing time. For our Alkali-Fix that would be 1.5 minutes to clear so a total of 3 minutes - when fresh.
Wash using the Ilford wash method.
If you've used an acid fix but still want to maximise tanning and staining, wash the film using alkalised water. Thornton recommended adding a small amount of sodium carbonate (1 heaped teaspoon per 5 litres) to make it alkaline. This, he said, would assist maximum stain formation and tanning after an acid fixer. Make sure the chemical is fully dissolved in the water before using it to wash the film and for a final wash, before rinse aid, use pure water for a couple of thorough rinses. Sodium bicarbonate can also be used but just 1/3 to 3/4 a teaspoon per 5 Ltrs - again, make sure it's fully dissolved and do a couple of good post wash rinses before rinse aid.
Printing with diXACTOL Ultra
diXACTOL Ultra pulls an enormous amount of detail from the negative. It prints on both graded and multigrade (VC) papers beautifully. In fact this is one of the main reasons I use it. There is a useful trick to printing with multigrade papers using split grade printing. This is just a starting point to realising the enormous detail that this developer pulls out of the film. From here you can perfect the print.
Make a print or test strip to ascertain the time needed to print at grade 2-3.
Now use this full time for exposing at grade 5 and 1/3 of this time for exposing on the same paper at grade 0. So:
- Example: If I find that a good grade 2.5 print uses an exposure of 10 seconds I will then start a split-grade test prints at:
- ~10 seconds exposure grade 5 followed by
- ~3 seconds exposure grade 0.
- You can expose the grade 0 first if you wish followed by the grade 5, it seems to make no difference.
- If your test strip is too dark reduce the grade 5 time.
- If you want brighter highlights reduce the grade 0 time.
This is a simple method to get you in the ballpark for split grade printing. There's other ways that I'll show on my YouTube channel but this works well as a starter.
Uneven Development with the 2-bath method
If you experience uneven development, often around the top and/or bottom of the film, using the 2-bath method then your film spiral might be contaminated. It seems that some chemistry just won't clean off the spiral easily. I use a clean spiral that I bought new from Paterson just for diXACTOL Ultra and have no issues with uneven development. However, should you not want to go this route then use the semi-stand development method which give very sharp and semi-compensated negatives like the 2-bath method. Thornton actually said that the negatives are even sharper than 2-bath!