Dr John Adamsons Calotype process .
Dr John Adamson of Burnside near St Andrews was a pivotal figure in early Scottish Photography, he mastered the Daguerreotype very early on, he and his younger brother Robert Adamson determinedly overcame the vagaries of Talbot’s Calotype and he latter went on to master the Collodion process producing some beautiful photography along the way . If you are interested then the Special Collections web page on the St Andrews web site is a great place to start , you can see how he developed his eye for photography and mastered the complex chemistry of the day.
The Calotype process was revealed to the photographers of St Andrews a couple of weeks earlier than it was patented in England during February 1841 and it took until the Spring of 1842 for the brothers to work out the pit falls of the process (and there are many) . In the Spring of 1842 John Adamson made the first portrait in Scotland a portrait of his sister Melville . By October 1842 Sir David Brewster in a letter to Talbot wrote “Adamson has arrived at great perfection in the art, and his brother the Doctor is preparing a little book containing his best works which I shall send to you soon.” This was the Tartan Album and marked the end of the experimental phase of the Calotype.
The brothers perfection of the process went from strength to strength with Robert finally setting up a studio at Rock House on Calton Hill in Edinburgh during May 1843 enjoying instant success as detailed by Sir David Brewster in a letter to Talbot "Mr Adamson who is now established in Edinburgh with crowds every day at his studio, will be greatful for your kindness . He will send you specimens of his progress which I think will suprise and delight you ". In July of the same year he entered into the legendry partnership with David Octavius Hill. John Adamson had trained his brother as a photographer and Robert had convinced Hill of the unique qualities of the Calotype.
Never let it be said that RobertAdamson was a bit player in their partnership , he wasn’t , he was the finest Calotypist of the day and the only person who came any where close apart from Talbot was his brother John. The pair appear to have been quite secretive about their manipulation of the process , because on the 15th August 1842 their fellow St Andrews Calotypist Sir Hugh Lyon Playfair wrote to Talbot pleading for more detail about the process , whilst on the Same day Brewster wrote to Talbot that “A Brother of Dr Adamson who has been educating as an Engineer is willing to practise the Calotype in Edinr as a Profession. I have twice discussed the matter with Dr A & will let you know more particularly about it in a few days after talking with Mr Adamson who has been well drilled in the art by his Brother.” Even Hill wasn’t certain what went on in the dark room ! Of course this is not to say that David Octavius Hill doesn't deserves his reputation , in my opinion he was a genius . It was a true partnership individually they were good together they were inspirational.
The work of the partnership has rarely been surpassed even today. It amazes me how they managed such a high quality and high volume output given that the Calotype really needs sunshine to excel and that they were working in a smokey Edinburgh which doesn'thave a great reputation for great weather.
It wasn’t until a year after Roberts early death in January 1848 that John revealed their process to the world . Where it must have been largely over looked ! In Chambers Information for The People Volume 2. 1849. Page 735. The authorship is not mentioned , but this article is mentioned in John Adamsons obituary. (Sarah Stevenson). This was a Victorian trait and in the many articles in this publication there is no mention of any author.
It is likely that this is the process his brother Robert Adamson used in his partnership at Rock House Edinburgh with David Octavius Hill. The brothers were close and it is unlikely that they didn’t share their findings.
The key points to this process are the Iodizing process , the omission of gallic acid in the sensitizer and the fact that the sensitizer strength is not set in stone . There is a lot of latitude for different circumstances, it is written by a master of the process and is unique for its time .Even after this was printed the information contained didn’t filter south of the border.
Until 2013 this process remained hidden in open view and it wasn’t until Richard Cynan Jones noted it in an article by Mike Ware called Pilgrims of the sun , that it came to my own attention . Roxanne Guez was the first to succeed with this process probably since the 1850s. It took me only one weekend to master the basics . It is superb.
My own comments and thoughts are laid out beneath Dr Johns masterpiece.
The other branch of the photographic art, by which the pictures of the camera are retained upon common writing-paper, is the discovery of Mr Fox Talbot, and was styled by him the Calotype (Or. kalos, beautiful). Depending in principle upon the blackening effect of light upon the salts of silver — a fact which had long been known to chemists — the idea of taking impressions of objects by this means was not new, although no one had met with much success in its practice. As early as 1802, Mr Wedgewood published a method of making profiles by the action of light upon paper or leather which bad been coated with a solution of nitrate of silver; but his experiments were attended with little success, and he was unable to preserve his pictures from the further action of light after he had made them. Mr Talbot himself, in a process communicated to the Royal Society on the 2lst February 1839, so far anticipated his own greater discovery; another step towards it was soon after made by the Rev. J. Reade, who employed the infusion of the gall-nut to increase the sensitive ness of the argentine preparation ; and finally, Mr Talbot divulged and patented the Calotype in February 1841.
It is this art, now usually called the Talbotype, which we propose to describe. It has been improved in some respects with the experience of eight or nine years, and it now differs materially from the original patented process in its details, although in principle it is still the same. The substances employed in it are — nitrate of silver, iodide of potassium, commonly called hydrio-date of potass, gallic acid, pure and crystallisable acetic acid, and hyposulphite of soda all of which may be obtained in a state of sufficient purity at the shop of any respectable chemist.
It is very much otherwise, however, with the paper on which the picture is to be taken; and we believe that many incipient photographers have thrown up the art in despair, because they did not happen to use good paper, and were not aware that their want of success could be owing to this cause. It is to be hoped that ere long the trials, now in the hands of more than one experimentalist, will result in the use of glass plates, or some fabric more perfect than any paper at present in use. The desirable qualities in paper are a smooth, fine, and uniform texture, with a sizing so strong, that the paper is not bibulous when put into water, and especially the absence of all chemicals, sometimes employed in its manufacture. These requisites have usually been found, in a tolerable degree, in a yellow post, bearing the watermark, Whatman, Turkey-mill, and better in old than in new specimens. Until some fabric of better qualities is produced, the photographer should examine all the varieties of paper he can find, in which he will be assisted by dipping them in water ; and having selected and marked the most perfect specimens, he should subject them to a comparative trial of the whole process, to discover the best.
The paper, before it is subjected to any of the preparations, should be cut into pieces a little less than the camera slide, as it expands when wet : and being marked to distinguish the side, each portion is to be coated with iodide of silver, by the following process proposed by Mr William Furlong in 1844 : — 25 grains of nitrate of silver are dissolved in one ounce of distilled water, to which about drachms of iodide of potassium is then added, and shaken until the copious yellow precipitate is re- dissolved. This solution is to be freely brushed over the marked side of the paper by a clean and dry camel-hair pencil, or with a little cotton wool. The paper is then allowed to dry spontaneously, or at a fire; and when dry, it is immersed in a basin of tepid (not hot) water, when it Speedily assumes a yellow colour by the precipitation of the iodide of silver into its texture. It may be placed in cold water, but then the yellow colour is longer in appearing. It is now to be well washed in several changes of water, or allowed to lie in it for an hour or two, when it may be again dried on clean blotting-paper, or at a fire, or pinned up to dry spontaneously. It is called by photographers iodised paper, and it may be kept for years.
The following solutions are required for the next steps of the process, which should be conducted by the light of a candle, or in a room from which daylight is nearly excluded by a red curtain : 1. A saturated solution of gallic acid in distilled water; 2. A solution of 50 grains of nitrate of silver in 1 ounce of distilled water, to which is added 2 drachms of pure crystallisable acetic acid ; 3. The preceding solution diluted with eight times its bulk of distilled water. When a picture is to be taken, the dilute solution No. 3 is freely brushed over the surface of the iodised paper by means of a camel-hair pencil, of the kind called ' swan quill,' or by a bit of cotton wool, which is more economical; and by the use of a fresh quantity for every application, is always clean. The superfluous solution, after about half a minute, is blotted off by one or more applications of clean white blotting-paper; and the paper, now sensitive to light, is carefully placed in the slide, to be conveyed to the camera-obscura. When the operation in the camera is concluded — which will occupy from twenty seconds to three or four minutes the slide containing the paper is reconveyed to the darkened apartment; and a mixture being made of equal parts of solutions Nos. 1 and 2, it if very freely brushed over the face of the paper as before, and allowed to remain upon it so as to be wet, until the picture, which soon appears, is sufficiently strong, or till the whole surface begins to turn brown. It is now to be immersed in clean water, where it may re main excluded from light for many hours, until it is convenient to fix the impression.
The above process admits of some variations: for example, a few drops of the gallic-acid solution may be mixed with the dilute solution No. 3, for application to the iodised paper, and it will make the impression come out sooner. If the sensitive paper must be kept some time, as an hour or two, before it can be used, then the solution No. 3 may be made more dilute, even to three times the extent directed, with advantage. If the picture unfolds itself of a reddish hue, more gallic acid should be immediately applied ; and if the whole surface darkens before the picture is sufficiently strong, it is often an indication that there is a want of acetic acid in the sensitive solution No. 3. In this case an additional quantity must be added; care being taken, however, not to use an excess, which impairs the sensitiveness of the paper. If the picture still appears of a dusky hue, the iodised paper should be exposed to the sun for ten minutes, which often improves it ; and if, after all, a good picture cannot be obtained, the fault in all probability lies in the paper itself. Some artists do not use the dilute solution No. 3, but make the paper sensitive by No. 2 undiluted, and bring out the picture by No. 1 alone.
The weather most suitable for the photographer is a bright day, with a clear blue sky and sunshine, if the object be to take buildings or views; for portrait-taking, however, a clear day without sunshine is preferable. Great success cannot be attained in foggy weather, or in the smoky atmosphere of a large town ; and some coloured objects, particularly such as are of a reddish or tawny hue, always make a comparatively feeble impression. We were once long puzzled on finding the por trait of an individual invariably covered with blotches corresponding to white spots on the negative, until at last it was seen to depend upon a multitude of freckles, scarcely otherwise perceptible! It is for the same rea son that many paintings cannot be well copied by the Talbotype; the reddish or yellow colours, which may be the brightest parts of the picture, reflect the chemical ray feebly, and are dark in the finished positive, while every tint of blue which reflects it strongly is in the same degree too bright. The negative, after being immersed in water for an hour, to be freed from all undecomposed nitrate of silver, may be preserved from the further action of light, or fixed, by simply wetting it thoroughly with the solution of hyposulphite of soda, when it is to be again immersed for some hours in clean water; but it may be fixed, and the yellow coating of iodide of silver re moved by one operation : thus — place it in a common earthenware dish of sufficient size, pour over it a few ounces of the solution of hyposulphite of soda, and then heat the dish over a fire until the yellow colour is removed, which will happen before the liquid approaches a boiling temperature. Another negative may be then whitened by the same solution. The hypo sulphite of soda should now be removed, by placing the negative in water for twelve hours, or by repeated washing. When the impression is not too faint, the negative may be improved by waxing it, which is accomplished by placing it on blotting-paper over any surface sufficiently hot to cause the wax to melt when rubbed upon the picture — an excess of wax, if any, being wiped off with blotting-paper. Black spots on any part of a negative may be obliterated by touching them with a solution of 20 grains of cyanuret of potas sium in 1 drachm of water, care being taken to prevent it from spreading. The same solution is useful for removing the black stains from the fingers, so characteristic of the Talbotypist.
Positive impressions are obtained from the finished negative in the following manner : To a solution of 50 grains of nitrate of silver, in 1 ounce of distilled water, add strong liquid ammonia until the precipitate which is at first formed is redissolved. This liquid will form a sufficiently sensitive coating on some kinds of paper, which may be discovered by trial. It acts well on a thick post by Nash. Brush it freely over the paper ; dry it thoroughly, either before a fire, or slowly in a room nearly dark ; and place it upon a flat board, which is covered with a layer of cloth or several plies of paper. Lay the negative over it with the picture-side downwards, and cover the whole with a thick glass plate, screwed down to keep the negative closely applied. When now exposed daylight or sunshine, the light passes through the negative, which gives a reverie impression of itself on the paper below, the lights und shades of the picture being now in their natural state. A convenient positive apparatus may be made by fixing the plate-glass in a frame, which is hinged upon the flat board, and secured by a catch or buckle. Some specimens of paper do not blacken readily with the above preparation, and in that case the paper must be salted, by dipping it in a solution of a teaspoonful of common salt in half a gallon of water. When dry, it will be found to answer. A solution of nitrate of silver alone may be used with salted paper; and by varying the strength of the nitrate of silver from 40 or 50 grains to 80 or 100 for each ounce of water, and exposing the positive frame to diffused daylight, or to strong sunshine, a variety of tints may be obtained for the positive picture. The time necessary to make a positive impression varies with the transparency of the negative and the amount of light. In bright sunshine, a light waxed negative will be copied in two or three minutes; while, in other circumstances, a whole day may be required. It is advisable to make the positive rather too dark at first, as it may be revived to any degree of brightness by the fixing process it has afterwards to undergo. It is now immersed in water for an hour, or washed in a weak solution of salt and water, to decompose any remaining nitrate of silver, and then laid in a dish in the solution of hyposulphite of soda. If the impression is not too dark, it should be soon removed; but if otherwise, it may be allowed to remain in it for some hours, or even a day or two, until it be reduced to the proper shade. The hyposulphite must now be carefully removed, by allowing the positive to remain not less than twelve hours in water, frequently changed, and, finally, it should be immersed in hot water for half an hour, to insure the complete removal of the salt. If this is not done, the impression may become gradually weakened after many months. It may now, if desirable, be fixed on Bristol-board, by means of issinglas, gum water, or weak glue. The positive process may be employed to copy lace, leaves of plants, manuscript, or printing on one side; etchings, engravings, or drawings, the first impression being of course a negative. A collection of valuable etchings may thus be copied without injury, and from each of the negative impressions so obtained any number of facsimiles of the original may be multiplied at a very trifling cost. It is a singular fact in the history of photography, that the first methods namely, these which we have now described in detail should have been given to the world almost perfect from their origin. Discoveries so remarkable could not fait to attract many experimenters into the same field; and the chemical action of light has now been minutely investigated in its relations to numerous substances. Such inquiries have naturally produced many new processes for the delineation of the images of the camera-obscura, as well as the less delicate methods by superposition ; yet none of these, as far as we know, has rivalled its progenitor either in the certainty or perfection of its results. It seems, therefore, sufficient to mention, that most of the new processes, as well as much information on the science of photography, are to be found in a series of papers by Sir John Herschel in the ' Philosophical Transactions of the Royal Society of London,' commencing in 1 840, and in a work entitled ' Researches on Light,' by Mr Robert Hunt. (Longman and Co., London.)
The amateur and professional artists employ almost exclusively the Daguerreotype and Talbotype, to the comparative qualities of which we shall now shortly allude, for the guidance of those who would attempt the practice of the art, but are uncertain to which pro cess they should give the preference. The peculiar characteristics of the Daguerreotype picture are its extreme delicacy and minuteness, which are sometimes even too minute for the unassisted eye to appreciate. By the aid of a magnifying -glass, objects have actually been seen most faithfully depicted, which, in the original view, required the use of a telescope to be observed. This extraordinary finish of detail, causing no detri ment to, but rather adding to the harmony of the general effect, imparts an inexpressible charm to these pictures ; for they actually seem to be the reality itself, and not an imitation. The portraits from the life which were first taken by this process had many faults: their hue was pale and leaden, and the length of time required for an impression was such that no features could retain their expression : the movements inseparable from a long sitting impaired also the sharpness of the form and outlines; and though still extraordinary in this respect, the picture had always a stiff and deathlike aspect. Now, however, by the increased rapidity of the process, by which a sitting of a few seconds only is necessary, and that in a light which can be borne without effort or pain, the Daguerreotype portrait seems to be the most perfect approach to the living reality which can be imagined the passing smile, the very softness of the skin of youth, are faithfully recorded.
In the Talbotype picture the effect is different, and it has a value also peculiar to itself. Its delicacy in a landscape or building is far inferior to the Daguerreotype, yet still the impression is as minute as paper can receive; and while the tone can be varied to almost any shade of reddish-brown or black, a good impression, once obtained, can be multiplied without limit, and at a cost which enables the amateur to distribute his works as widely as he may desire. For this last reason also the Talbotype is continually available, and affords a perpetual source of amusement.
It has been said that a common incident, graphically narrated, excites as great an interest as a wonderful ad venture; and so also do we derive pleasure from the graphic delineation which the Talbotype gives us of even a common object : a bush, a stone, or an effect of light, may exhibit as much of the beautiful and picturesque as a study of much pretension. To the painter, such subjects are invaluable — they show him ow nature should be viewed ; and we could name those in the highest rank in that profession who have taken lessons in this school, and have not been ashamed to avow their master.
Many portraits by the Talbotype are not good or pleasing likenesses, from imperfection in the paper employed, or from a look of distress, or total want of animation, sometimes unavoidable in a process still too long. Individuals whose habitual appearance depends more on the expression than the form of their features, may also fail to obtain a good resemblance. But many people dislike these pictures from inability to appreciate their beauties. A glaring daub may be more prized by the vulgar than a valuable painting by the hand of a master; and the Talbotype of rare beauty is sometimes despised because it has not the brilliant colouring or the open eyes of a commonplace portrait or miniature. It is worthy of remark, that those who are acquainted with the works of Titian, Rubens, Rembrandt, and other great painters, are no less surprised than delighted to trace the resemblance in their pictures to the impressions of the Talbotype, proving in this manner the true observation of nature by the ancient masters. And when the skill of the artist in arranging the subjects is combined with dexterity in the photo graphic manipulation, no painter's hand can compete with these productions of nature herself in the fidelity and power of their expression. We have seen Talbotypes produced jointly by the late Mr Robert Adamson and Mr D. O. Hill of Edinburgh which warrant these remarks, and have obtained this tribute from the greatest among the painters of the present day.
Specimens of this art have been published by the inventor himself in a work entitled ' The Pencil of Nature' (Longman, Brown, and Co., London); and may be obtained from Messrs Henneman and Malone, Regent Street, London ; and from Mr Alexander Princess Street Edinburgh .
My comments , experiences and thoughts,
Double Iodide of Silver.
Wear gloves , and old clothing . No food or drink in the dark room.
Silver nitrate 1.62 grams
Distilled water 28.41mill.
Potassium iodide 13.6 grams.
Stir the silver nitrate into the distilled water until it dissolves. Then add the Potassium Iodide the water turns bright yellow . Keep stirring until the water clears . This takes about a minute and I always marvel when it does. This is the young William Furlongs genius at work . In one fell swoop he simplified Talbot’s Iodizing process as well as the later English method of producing double Iodide of sliver. This produces a very reliable Iodized paper.
With a hake brush, brush this on to your paper which has been pre cut slightly larger than required. I cut the paper about 1cm longer to allow for handling during the sensitization stage.This solution will cover about 20 pieces of 5" x 4" paper.
Wash under running water for a minimum of 2 hours 4 is good 8 is better. Trays of water changed at regular intervals is fine. Dr Johns method of using tepid water to bring out the yellow colour of the Iodized Paper works well. Hang up to dry . I do the brushing and washing under red light conditions in the dark room. At the end you should have evenly coated primrose coloured paper. Store them in a cool dry place. I have recently used paper Iodized two years ago with no problems.
DARK ROOM !!
Apply with cotton wool.Use a fresh ball of cotton for every application.
Prepare solutions #1 and #2.
1# Gallic acid in water 0.4%
2# Aceto Nitrate of silver
Silver nitrate 11.4 grams
Distilled water 100mill
Glacial acetic acid 25 mill.
3# Distilled water 8 parts or 10 mill
Solution 2# 1 part or 1.25mill
To increase sensitivity add a few drops of 1#
3# can be diluted for better keeping properties. By 2 or 3 times .
Canson marker needs 3# to be diluted 3 times plus 2 extra drops of Acetic acid per 10 mill.
Ruscombe Timothy 2 and Bienfang 360 need to be used at full strength.
Sandwich the paper between 2 pieces of glass to prevent the paper either rippling or fouling the dark slide. . I have exposed 4 hours and developed the paper 8 hours after sensitization with no loss of quality. You can either gently blot the paper dry , or use it wet .
Equal parts of 1# and 2# brushed on .
I float on a saturated solution of gallic acid in 100mill distilled water and add 1 mill of 2# after 10 minutes .
Bright summer sun Ev14
F22 is 12 minutes
F4 is 23 seconds.
Timothy 2 and Bienfang.
F22 is 24 minutes
F4 is 45 seconds.
As of 2015 Canson have changed something in their paper and it develops spontaneously,. The Ruscombe Timothy is a very fine alternative. Although it is one stop slower.
When things go wrong refer to Dr Johns wisdom the answer will be in his article.
Ammonio-nitrate of silver.
50 grains (3.24grams) of silver nitrate . In one ounce of distilled water . (28.41mill) 11.4% Add Strong ammonia (34%) the water immediately blackens. Add the Ammonia drop by drop until the solution starts to clear. It is best not to let it clear completely but stop adding the Ammonia whilst it is very slightly cloudy. If you add too much Ammonia the solution is too weak leading to sensitization problems . If you do add too much then add a few grains of silver nitrate so that the water clouds again. Wear goggles and a mask and mix in front of an open window. Strong Ammonia is very unpleasant. It goes without saying that you should wear gloves .
6 grams of sodium chloride in 2250 mill of water . = .27%. This works well with the modern Canson XL.
I apply this with cotton wool.
Dry with a hair dryer and use immediately.
Bare in mind comments regarding paper by Nash the low % of salt is for papers other than Nash.
2% salt 1% gelatin works well .
Nash paper mill started paper making at the end of the eighteenth century.
Situated in Hemel Hempstead. Closed in 2006 . Now a housing estate.
Robert Bingham also recommended Nash paper in his article of 1847.
"For obtaining the positive pictures , the texture of the paper is not of so much consequence. We find the best for this purpose to be a variety manufactured by Nash; it contains no water-mark, and is very white: it also contains a small quantity of the chloride of lime used for bleaching the paper, but which is accidentally a great advantage, for the silver wash may be applied without any previous preparation of the paper ; and the chlorine exists in the paper in the proper equivalent proportion. We have seen some very fine pictures said to have had their negative photographs taken upon this paper, but we confess that in our hands it has not proved at all successful for this purpose. The defect is, it is too new and the positive pictures obtained are very coarse and woolly in appearance "
I wonder where and how the Adamsons purchased their paper ? They used different of varieties of paper even in the same sitting.
Could this be the process Robert Adamson used in his partnership with David Octavius Hill ?. George Cundell also details a diluted sensitizer and varying the quantity of acetic acid in his paper on Gallo Nitrate of Silver in 1846 .
Bingham also used a diluted sensitizer detailed in his manual of 1847 called Photogenic manipulation. He also recommends paper by Nash.
What is certain is that John Adamson was very well informed, very intelligent and an excellent photographer and chemist . There was a chance after his brothers early death at the age of 26 in January 1848 that Dr John would go into partnership with David Octavius Hill . One can only imagine what marvels they would have produced. In the event Dr Johns profession drew him away from this career path and back to St Andrews where his next Protege was a young man called Thomas Rodger.
In Ermin ,Tate and Berry’s paper on the chemistry of John and Robert Adamson’s salted paper prints and Calotype Negatives there is no mention of Ammonio-nitrate of silver. Yet John Adamson , Talbot , the Reading Establishment and Bingham all recommend this method for printing .
I wonder where they obtained their chemicals ? Impure or adulterated chemicals were often the cause of failure . Chemists varied in their methods of production and even individual chemists varied their method from week to week. What was needed was a reliable , consistent and discrete source . I don’t believe Robert Adamson had the time to make his own chemicals given his prodigious output during his partnership ship with David Octavius Hill . (Octo) Could Alexander Govan of St Andrews have been that source . It is likely that he was taught the Calotype process by Dr John and his Album in the Special collections department at St Andrews contains many works by Hill and Adamson as well as Dr John.
In Chambers' Information for the People, Vol II, 1849. the authors name is not mentioned. So I asked Mike Ware how he and Roger Taylor his Co authhor arrived at that conclusion. This is the reply I received from Mike. Good to hear from you. Having no idea about the answer to your question, I asked Roger T., who thought he got it from Sara Stevenson - who does indeed turn out to be the source of all Scottish Photography wisdom - see appended emails below.
And Sara's response -
The answer - or an answer - comes from his obituary. Do you know the Wellesley Index which reveals the authors of most of the contemporary journal articles? It may be in there too if Rob D wants to check further. Anon [perhaps Oswald Home Bell, his partner] ‘Obituary. Dr John Adamson. – In Memoriam’, Edinburgh Medical Journal, XVI (1870-1), pp 286-8 http://www.forgottenbooks.com/readbook_text/Edinburgh_Medical_Journal_1871 _1000143465/297
'Though leaving no [p288] work of importance behind him, he was the author of several papers on Sanitary Reform in the medical journals, of the number on Photography in “Chambers’s Information for the People,” and of pamphlets on the Health and Drainage of St Andrews, and on the Evils of the Licensing System as at present practised by the local magistrates. In all of these there is fair talent and much earnestness...' Delighted to hear JA's instructions still work. Presumably they incorporate that fine thought from DOH, "Mr Adamson knows some things others do not...'
Non destructive analysis of Adamsons and Hill’s Calotypes by Ermin ,Tate and Berry show that they used Potassium Iodide, Potassium Bromide , and Sodium Thiosulphate to fix their Calotypes. Early examples used Potassium iodide and bromide, later ones predominantly but not exclusively Sodium thiosulphate .
Talbot’s method in note book Q note 96 was 500 grains of Potassium Iodide in 1 pint of distilled water. 5.75%
Potassium Bromide fixation is a 2-3 % solution .
One of John Adamsons prints is fixed in ammonia , I have found mention of this method by Sir David Brewster but it doesn’t give any specific detail.
Note that Adamsons Sodium Thiosulphate is a "solution " there are no specifics. There is the possibility that they varied the strength of the hypo.
I have recently tried fixing with Potassium Iodide and Potassium Bromide and it didn't seem to yield any advantage to fixing with Sodium Thiosulphate. I had hoped that the Potassium Iodide would clear the whites of a dense calotype, but the effect was neglibible. I had surmised that the Adamsons adapted the fixer according to the how the Calotype developed. I need to test this further. Of course there may have been a simpler explanatation , the Sodium Thiosulphate may have been in short supply or of questionable quality .Like many things Hill and Adamson I guess we will never know for certain.