From: Richard Morris (Richard.Morris@brunel.ac.uk)
Date: 02/19/02-02:38:26 AM Z
Here are my notes on making calotypes and salt prints. They are takn from
the original formula as used by John Dillwyn Llewelyn who based them on
Talbots original. Most photographers of the period who used the process had
their own variations. Nothing was sacrosanct then!
Any problems do let me know.
THE CALOTYPE PROCESS
On September 20th 1840 William Henry Fox Talbot made a momentous
discovery, the development of the latent image. This, added to his previous
discovery of the negative/positive process in 1834, laid the foundation for modern
photography.
Talbot communicated the process to the Literary Gazette in two letters dated 5th
February and 19th February 1841 but without any specific details. Professional
operators required a licence from Talbot though amateurs were usually exempted.
No licence was required in Scotland where Hill and Adamson made their fine
portraits by the process.
The Calotype process is a real do-it-yourself photographic process. It relies on a
paper negative and all the sensitising has to be done by the calotypist. Chemicals
are usually easily obtainable, but there will be variations in purity compared to
Talbot's period so it is worth trying variations on the formulae.
There are several distinct steps in the process, each of which must be carefully
followed. Forget the motor-driven 72 exposure cassettes. This is a leisurely one at
a time process!
MAKING THE IODISED PAPER
This may be carried out in subdued daylight, or preferably under ordinary domestic tungsten
lighting.
Materials required:
1. Paper for the negative
2. Silver nitrate crystals
3. Potassium iodide crystals
4. Distilled or de-ionised water. NOT tap water
5. Cotton wool
6. Plastics tube
Chemicals are applied by a Buckle Brush, named after Mr Buckle an early calotypist. This is a
glass tube through which cotton wool is drawn to create a tuft at one end. Today it is easier to use
a plastics tube and stuff a piece of cotton wool in one end to create a tight ball. It is not advisable
to use a lare watercolour brush as any metal may contaminate the chemicals. It is also almost
impossible to clean the brush afterwards. Some brushes, made from artifical fibres may even melt!
Chemical mixes for Iodising:
1. Make a 7.5% solution silver nitrate in distilled or de-ionised water.
2. Mix 16 grammes Potassium iodide in 284 ml of distilled or de-ionised water. Approx 5.6%
solution.
Action:
1. Clip a piece of paper to a board, with a sheet of CLEAN blotting paper underneath, to
keep it flat. Mark the upper side with an X.
Using the Buckle Brush coat this side with the silver nitrate solution so that it is well
covered.
2. Leave until it is matt damp - no pools of liquid - then immerse in the Potassium Iodide
for at least two minutes. This converts the chemicals to silver iodide and potassium
nitrate.
3. Wash paper for several hours in changes of water.
4. Hang up to dry.
5. When dry hang up in bright sunlight for up to two hours. This increases the contrast
of the paper. The silver iodide has an excess of iodide and so is insensitive to light.
Should any brown blotches appear, the chemical conversion is incomplete leaving free
silver nitrate. Throw away.
6. Store the paper in the dry in archival bags. Do NOT use old boxes that contained bromide
printing papers - these exude lethal, to the iodised paper, chemicals.
SENSITISING FOR CAMERA USE
This MUST be carried out under non-actinic light. Calotype paper is sensitive to blue light
only so a yellow or red light may be used but at a greater wattage than for bromide papers. A
red or yellow lacquered bulb may be safe.
Chemical mixes:
A different set of chemical mixtures are required for the process.
1. "A" - Silver nitrate 11.4% solution in distilled or de-ionised water
2. "B" - Into 28.4 mls of the above put 5.5 millilitres of Glacial Acetic Acid.
3. "C" - Saturated solution of Gallic Acid in distilled or de-ionised water. In warm
weather this will oxidise in a few hours
4. "D" - Distilled or de-ionised water
Keep the silver solutions in a dark brown bottle away from direct sunlight.
To sensitise a negative:
1. Clip a sheet of the Iodised paper, X marked side up, to a clean piece of
blotting paper on a stiff board. Using a pencil mark the size required for
the negative.
2. Take 4 millilitres of distilled water and into it add 3 drops of "B" followed by
3 drops of "C".
3. Coat this mixture onto the "X" marked side of the paper using a CLEAN brush.
Make sure the coating is even and liberal.
4. Leave at least two minutes then using a CLEAN piece of blotting paper, firmly blot
the paper. Some people prefer to let the paper dry naturally.
5. Cut to size for the camera.
6. Put the negative into the camera sheet film holder, sensitised side towards the lens.
7. Put in the darkslide.
You can now go outside and take a Calotype.
Sheet film holders
Modern metal cut film holders will probably be safe to use. Older ones may exhibit rust and should
be avoided.
If using an old wooden film holder the following precautions may be necessary. Old dry plate
holders usually have a spring to keep the glass plate in place. Use a piece of black card behind the
calotype negative paper, and ideally a piece of thin Mylar (a conservation material used for storing
photographs) between the paper and the card. Place a sheet of thin clean glass on top. This
prevents the damp paper catching on the dark slide and also being contaminated by the adhesives
used in the cloth hinges of the slide.
CAMERA EXPOSURE
In Talbot's day it was done by trial and error. Today it is possible to use a light meter to assist, but
even this requires some human involvement.
With an old Weston Meter if the needle is on 100 then an average exposure at f4.5 will be 30
seconds. This is equivalent to 1/500 second with an film rated at 125 ASA!
If the needle is on 200 then halve the exposure; if on 50 then double.
Try less exposure time in the middle of the day when there is more ultra violet light about. Modern
coated lenses may also require a shorter exposure as they let through more light.
Calotype paper when sensitised will not last very long if left out in the hot sun in a film holder.
Always keep it cool. If kept in an insulated bag with an ice pack it should last all day.
Talbot himself had problems with his paper especially when making 'Sun Pictures of Scotland'. He
had to desensitise the paper to keep it. This resulted in longer exposures and poorer negatives.
DEVELOPING THE NEGATIVE
This must be carried out under non-actinic light - ie: light with no blue in it. A red or yellow
lacquered bulb may be alright. A normal tungsten bulb is not safe. It is also advisable to keep the
darkroom cool - ie: below normal temperature. A warm darkroom will make the chemicals go off
more quickly and it also appears that negatives developed in the cool are clearer than those done is
a warm room.
Chemicals required:
1. Equal quantities of "B" [aceto-nitrate of silver] and "C" [gallic acid] without any additional
water. Put about 4 millilitres in a CLEAN pot. This will not keep for very long in a warm
room.
2. Neat Gallic acid "C".
3. Several clean buckle brushes.
4. Hypo. NOT a rapid fixer. Best results come from Kodak UNIFIX mixed from powders at
normal mix for films (the negative is very rich in silver) or from plain hypo crystals in
about a 15% solution. [Kodak Unifix bought in liquid form contains ammonia in Britain].
To Develop:
1. Place the exposed negative "X" side up on clean blotting paper and hold carefully at each
corner with a clip.
2. Using the combined "B" and "C" mix above wash over the negative using a CLEAN brush
until the image begins to appear. Do not use more than enough to moisten the paper and
make sure that you brush it on evenly.
3. Allow the image to develop then, using a CLEAN brush, apply neat Gallic Acid "C". Do
NOT flood. Leave until the image ceases to strengthen.
4. Apply more Gallic Acid if necessary to increase the contrast.
5. The negative will be ready when, if held against the light, there is a strong contrast
between dark and light parts. If the whole negative appears to be fogging cease any further
development. Development has been known to take several hours if the darkroom is cool!
6. Wash the negative in clean tap water to remove surplus chemicals.
7. Fix in hypo for five minutes. Change to a fresh bath for a further few minutes. A properly
fixed negative will not show any yellow which is unfixed silver iodide. Talbot suggested
BOILING hypo as giving a clearer negative.
8. Wash for at least one hour. Hypo elimininators can be used
9. Dry the negative by hanging up to dry naturally
10. When dry wax with bees wax, or any white wax, to make the negative translucent and also
less liable to tear.
HOW TO WAX
Place the negative face down on clean blotting paper. Place another sheet on top and go over with a
hot iron set to maximum temperature. Lift blotting paper a rub wax into negative. Repeat until the
negative is evenly waxed. If the negative turns yellow under the heat you have failed to fix it
properly - too late! But it may still print. Alternatly sprinkle wax onto the top piece of the blotting
paper and iron in.
Eventually the blotting paper will itself become impregnated with wax. Use this on top and replace
the underneath piece with fresh blotting paper.
Waxing is not always necessary with some thin papers. It is interesting that Hill and Adamson did
not generally wax their portrait negatives.
Waxing has several functions. Firstly is helps to reduce the fibres in the paper negative so that they
do not show in the print. Secondly a waxed negative will print faster. Third it does make a
'tougher' negative less easily torn.
Bees wax may be used or paraffin wax obtainable from art shops.
PRINTING PAPER
Talbot's printing paper was made by the same process as his Photogenic Drawing paper, as
discovered in 1834. Basically it is of rag/gelatine mix and even in Talbot's days, he had
preferences for certain years of Whatman manufacture. Modern rag papers may often contain
bleaches It ich are injurious to the photographic chemicals. 'Salt' paper is a very soft daylight
printing paper which is why Calotype negatives need to be contrasty. If you were to make a
negative on a Grade 4/5 multigrade paper this would be of sufficient contrast.
Solutions required:
1. "E" - sodium chloride (common salt) approx 2-3% solution in tap water.
2. "F" - silver nitrate approximately 12% solution in distilled water. To this add SLOWLY
strong ammonia (approx .880 NOT Scrubbs Household Ammonia - this is too weak) until
the muddy appearance just clears. A few drop of Nitric Acid may also be added. This
seems to help in preserving the sensitivity of the paper on a hot day.
3. Fixer - use a plain hypo or non-ammonia fixer. Mix as for normal prints or approx 15%
solution. Temperature is not critical - Fox Talbot did suggest boiling fixer!
Method:
1. Soak a piece of paper in salt solution "E" for about two minutes. Make sure there are no
bubbles. Hang up to dry.
2. Brush solution "F" onto one side only. Mark with an "X". Allow to dry.
3. Cut paper to required size.
To Print:
1. Place the negative and salt paper face to face, ie: sensitised sides facing each other, in a
daylight printing frame or else a piece of glass and a backing board clamped together.
Printing will take place through the back of the negative.
2. Put out in sunlight and inspect from time to time. When the print appears darker than ideal
take indoors. Always inspect in the shade or indoors.
3. Wash print in running water until the water clears. NB - at this stage the print appears to
be very sensitive to light.
4. Fix in HYPO bath (15% solution) for about 5 minutes. The purple colour of the print will
change to an orange/brown colour. Transfer to fresh fixer for a further 5 minutes. NB -
One litre of fixer will fix about ten 1/1 plate size prints.
5. Wash in running water for about one hour. Hypo eliminators may be used.
6. Allow to dry at room temperature.
7. When dry iron the back with a hot dry iron. This restores some density to the image.
I have found that a 2% salt solution gives a brown print, 3% more towards grey/brown. However
different papers give different coloured results.
Alternative fixer if 15% potassium bromide, also used by Talbot. Gives a warm print. I am not
sure how long this lasts. I have had bromide prints go cloudy but a wash has restored their colour
and clarity.
Congratulations - you have just made a real Calotype.
ARTIFICIAL LIGHT EXPOSURES
Exposure may be made under artificial light but will need at least four times longer exposure than
in daylight.
Flash could be used but the flash duration appears, from some trials, not to be long enough to get
the paper working.
DARKROOM ILLUMINATION
In Talbot's days illumination was generally by candle light. It was Antoine Claudet who discovered
that red light was safe with photographic emulsions. The Calotype process is only sensitive to blue
light so any lamp than does not extend to this part of the spectrum may be used.
SOLUTIONS REQUIRED
Chemicals should be easy to obtain through some chemists, photographic dealers or specialist
companies such as Sherman Chemicals, Suinderland Road, Sandy, Bedfordshire SG19 1QY
Iodising: 7.5% silver nitrate solution in distilled water.
16 grammes Potassium Iodide in 284ml distilled water. Approx 5.6% solution.
These two are kept in separate bottles. The silver solution should be kept in a dark
brown bottle in a cool place. The mixed iodide keeps for a long time in the cool.
Sensitising: "A" 11.4% silver nitrate in distilled water
"B" Into 28.4 ml of "A" add 5.5 millilitres of Glacial Acetic Acid.
Keep both of these in dark brown bottles.
"C" - saturated solution of Gallic Acid [3,4,5 Tri-hydroxybenzoic acid - NOT to be
confused with Pyrogallic Acid]
Distilled, purified or de-ionised water.
Developing: Same mixtures as for sensitising.
Printing: Approx 2-3% solution of common salt (sodium chloride). In Britain I use Dentritic
salt, as used for water softeners, which comes from the Cheshire salt mines.
Sea/Rock salt is also OK. Some domestic table salts have additional chemicals and I
have found very curious results: uneven salting of the paper.
12% solution silver nitrate.
To this can be added a few drops of Nitric Acid. Also strong ammonia until the
solution just clears. This makes the prints slightly browner.
PROCESSING TEMPERATURES
Talbot makes no mention of temperatures except to suggest that BOILING hypo helps clear
negatives better. Normal room temperature is adequate. But if the room becomes too warm
chemicals may go off. A cool darkroom is actually best even if negatives do take a bit longer to
develop.
TAKING PORTRAITS
Remember that the process is only blue sensitive. Therefore avoid portraits after a visit to the pub!
Note also the appearance of greens in the negative or print. A good way to see what the final image
might look like is to view it through a high cut blue filter.
PAPERS
Talbot's papers were of rag/gelatine mixtures. But not all old papers are good just as all modern
papers are bad. Experiment. I use an old paper STAG - Turkey Mill.
The chemical conversions are from the original obsolete measures used in the 19th century. They
have been converted to the nearest first decimal place! I don't think they are too critical as modern
chemicals probably differ from those used by Talbot et al - probably too pure.
SOURCES OF INFORMATION ON THE CALOTYPE PROCESS
The two best are the Patents of Talbot in the Patent Office, London. Also early issues of the
Journal of the Photographic Society - especially the article by John Dillwyn Llewelyn in Volume 1
- this volume has been issued in replica form and may still be available from the Royal
Photographic Society. As Llewleyn was married to a cousin of Talbot's there was a close
relationship between them photographically. Many early publications may be found in specialised
libraries.
Richard Morris FRPS
Long Gable
Cherrytree Lane
Chalfont St Peter
Bucks SL9 9DQ
e-mail: richard.morris@brunel.ac.uk or morris1856@aol.com
On Mon, 18 Feb 2002 09:46:22 -0500 (EST) ARTHURWG@aol.com wrote:
> I would like to make paper negatives and salt prints-- like Dan Estabrook
> does. Can anyone suggest a source of instructions for paper negatives, what
> kind of paper to use, what emulsions, etc? Thanks. Arthur
Richard Morris
Brunel University, UK
dtsrrlm@brunel.ac.uk
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