ARGYROTYPE
Mike Ware
(version of 12 August 1994)
A new 'user-friendly' iron-based silver printing process, related to the
Kallitype, Argentotype, Sepia, Brownprint and Van Dyke processes of the
19th Century, but offering some advantages over them in the economy of
materials and effort, and in the quality and permanence of the image.
Sensitizer Chemicals needed:
Sulphamic acid 7 g (spelt 'sulfamic' in the USA)
Silver(I) Oxide 7 g
Ammonium Iron(III) Citrate (green crystals) 22 g
Tween 20 (wetting agent) about 0.2 cc
Distilled water to make 100 cc
Making up Sensitizer (under tungsten light)
1) Heat about 70 cc of distilled water to 50-60 C, and dissolve 7 g of
Sulphamic Acid in it.
2) Add 7 g of powdered Silver(I) Oxide to the hot solution 1) in small
amounts with vigorous stirring until all is dissolved.
3) Add 22 g of Ammonium Iron(III) Citrate (the green variety) to the warm
solution in portions, with stirring, until it is all dissolved. Allow to
cool.
4) Add 0.2 cc of Tween 20 and mix well.
N.B.The appropriate quantity of this wetting agent is variable and will
depend on the paper used.
5) Add distilled water (at room temperature) to make a final volume of 100
cc and filter the solution to remove any small amount of solid remaining.
(The solution should be a clear deep olive-green colour.)
6) Store in a brown bottle in the dark at room temperature.
(The solution should keep for a year, at least. If it throws down a small
amount of black precipitate, it should be re-filtered.)
7) To make a more contrasty sensitizer, dissolve an extra 1 g of sulphamic
acid in 100 cc of sensitizer.
CAUTION The solution is toxic and will stain skin and fabrics: wash away
spillages with plenty of cold water.
Papers
The purity of the paper is critical: of the UK papers tested so far,
Whatman Watercolour, Saunders Somerset and Atlantis Silversafe Photostore
are recommended, but the best is Ruscombe Mill's handmade Buxton paper.
The wetting agent, Tween 20, is included in the sensitizer formulation to
assist uptake of the sensitizer by the cellulose fibres, which minimises
"bleeding" of the colloidal metal image during processing, but it may cause
uneven penetration of some papers that contain a mixture of fibres.
Discovering the best paper is a matter for personal experiment.
Coating
A 10"x8" coat requires about 1.6 cc, depending on the paper, if a glass rod
spreader is used. Brush coating will consume more.
Allow a few minutes for the sensitizer to soak in, until the paper surface
appears non-reflective, then dry for about 10 minutes in a stream of warm
(40 C) air. Alternatively, simply allow to dry at room temperature and
humidity for about an hour. The sensitized paper should be used within a
few hours, unless a desiccated box is used for longer term storage: 'shelf
life' in a dry environment is at least a week.
Printing
As with platinum-palladium printing, a negative with a long density range
(0.2 to 2, or so) is desirable, obtained by "overdeveloping" by 70%-80%.
Softer negatives may be accommodated by using the more contrasty sensitizer
recipe. [Indeed, by mixing the two formulations, the contrast of the
sensitizer could be 'fine-tuned'.]
Printing is by contact, using a UVA source or the sun. Exposure is similar
to other iron-based processes, e.g. platinum/palladium.
If the relative humidity of the paper is 'normal' (ambient RH between 40
and 80%), a detailed print-out image will be obtained, orange-brown on a
yellow background, which gives a good indication of correct exposure,
making test strips unnecessary. A little development (half to one stop) can
subsequently be expected to occur in the high values during wet processing,
and there will be considerable 'dry-down' of the tonality: both factors
should be taken into account in judging exposure; the colour will also
darken to a rich brown in the fixer bath. It is better to overexpose than
underexpose, because a dense image can be 'reduced'.
Colour
The colour of the print-out image may be shifted to a more neutral tone if
the sensitized paper is humidified before exposure by leaving it above
water (100% RH) for 30 minutes at room temperature. This is a very
economical method of colour control!
CAUTION: Humidified sensitized paper can damage negatives during contact
printing unless a protective layer of very thin polyester film is
interposed between the two.
Wet Processing
This is extremely simple and non-critical, requiring only one inexpensive
solution, 2% Sodium Thiosulphate: dissolve about 20 g of the crystals in 1
litre of water. This bath has a capacity of about ten 10"x8" prints and
should be replaced when necessary.
1) Develop and clear in running water at room temperature for 5 mins.
2) Immerse in the 2% Sodium Thiosulphate clearing bath for about 3 mins.
3) Wash the print in water for 20 mins and air dry at room temperature.
NOTES:-
1) The yellow unexposed sensitizer should disappear completely within
this time. If there is any "bleeding" of colloidal silver metal, indicated
by a red-brown stain running off the image and loss of image density, then
this problem results from the paper fibres failing to trap the tiny silver
particles; it is especially likely if insufficient Tween is used. The
effects of "bleeding" may be minimised by processing the print face down,
to avoid staining adjacent areas. If a particularly long tonal range is
desired with very delicate high value gradations, the exposed print should
be left in a humid atmosphere (100% RH) for ten minutes before wet
processing; several steps of highlight detail will build up.
2) The image should intensify in the fixer, improving the shadow
gradation, and the colour will rapidly transform from red to brown. (As the
bath 'ages' its action in this respect increases). Overlong treatment in
this bath and exposure to air will result in loss of image density
especially in the highlights; it may be used to 'reduce' an overexposed
print, or a standard, non-acid fixer may be used. If, on the other hand,
very delicate highlight detail is desired, a little ammonia may be added to
the clearing bath to make it distinctly alkaline (pH 9 to 10); this
inhibits the dissolution of silver, but may raise the level of residual
iron in the image.
3) The image 'dries down' significantly - at least one Zone. Heat
drying on a ferrotype plate or by ironing, may shift the colour to a more
neutral blackish brown.
Permanence
Like any colloidal silver image, an Argyrotype is inevitably rather
susceptible to attack, especially by acids and sulphur-containing
substances. However the residual iron and silver in the unexposed areas
should be very low and image stability and lightfastness are good.
If improved permanence is desired, then try selenium toning (Kodak selenium
toner, diluted 50 to 100 times for a minute or so). Toning with gold,
platinum or palladium should also be possible, and the image should also
respond readily to sulphide toners, but I have not yet tested all these
options.
Disclaimer
This information may be copied and circulated freely (preferably with
acknowledgement!), but the author cannot accept liability for any injury,
damage or loss resulting from its use.
Reference
'The Argyrotype Process' by Mike Ware, British Journal of Photography,
No.6824, 13 June 1991, pp. 17-19.
A made-up Argyrotype sensitizer solution should be available from
Silverprint Ltd., address in the List's FAQ.