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Understanding photographic printing techniques
Knowing how your print was made will help you to understand its value and how to preserve it
To really understand your photograph, you will need to have a good idea of how it has been made. Knowing the techniques that have been used to create a print will help you to ensure you are paying a reasonable amount for it, care for it, and understand its changing value. However, the terms used to describe photography techniques can seem obscure, especially for new collectors. In the following pages, we outline some common print types that you are likely to encounter, with reference to the Visual Glossary created in partnership between Paris Photo and the ARCP (directed by Anne Cartier-Bresson).
The Visual Glossary is housed on the Paris Photo website and is available in both French and English. It is a helpful tool, detailing and illustrating both contemporary and classic techniques, and is continuously updated throughout the year. If you would like to read more extensively on different techniques, the glossary is a good place to start.
The albumen printing technique quickly gained popularity upon its invention in 1850, as it produced more precise, contrast-rich images than earlier photographic methods. The process involves floating paper
on an albumen (egg white) solution, before coating it in silver nitrate, creating light-sensitive silver salts on the surface of the paper. A negative is then placed on to the paper, leaving an image when exposed to light. Albumen prints can deteriorate easily, with their most prominent areas of decline being highlight yellowing, highlight definition loss, overall image fading and image colour change. Much of this decline comes from their sensitivity to moisture, and they are preserved best in 30 to 40 percent humidity.
Chromogenic Print (aka C-print)
Sometimes called a C-print, a chromogenic print is a full- colour, silver-based photograph produced from a colour negative, slide, or digital image. The process, in which dyes are produced by a chemical reaction and attached to gelatin layers, was developed in the 1930s. Thanks to its low cost and versatility (it can work on matt, gloss and ultra-gloss surfaces), it was the most popular printing technique until the emergence of digital printing. Because the dyes used in this process are unstable, chromogenic prints are prone to fading. They need to be stored away from light and at low temperatures: –2°C is optimum, according to the Library of Congress.
This quick, simple and low-cost printing process involves applying a solution of ammonium iron citrate and potassium ferricyanide onto paper, before leaving it to dry and then exposing it to the negative. The cyanotype is one of the oldest monochrome processes which does not use silver salts. Though its distinctive blue colour led early commercial photographers to avoid it, since the mid 20th century many have experimented with its artistic possibilities. Unlike most other print types, cyanotypes can react to alkaline- buffered materials, so it is best to use unbuffered paper when housing your print. They also fare best in porous wrappers, rather than airtight ones.
Pigment ink print (aka Giclée print)
First developed in the 1950s as a means of printing text, the inkjet printing process only developed into the pigment inkjet printing process in the 1990s. It is used to print from digital files (whether or not the original image is digital). Using a system known as Drop on Demand, in which ink droplets are ejected using a thermal or piezoelectric system, pigment ink printing results in high-quality, long-lasting prints, which work on a variety of surfaces. It continues to be used widely.
Salted paper print
When the salted paper print was invented by William Henry Fox Talbot in the mid 1830s, it revolutionised photographic printing, being the first positive print obtained from negatives. The process initially involved using writing paper wetted with a salt solution and brushed with silver nitrate, making it highly light-sensitive. Later developments saw binders being added to the salt solution to enhance definition and contrast in the prints. Salted paper was hugely popular in Europe, especially in France, until the 1860s. These prints are highly prone to light damage, and require individual care, so make sure you enquire as to how best to protect them when buying.
The gum print process hinges on the discovery that gum arabic becomes insoluble in water when exposed to light. A gum print is produced by applying gum and pigment to paper and then washing it, which can be done several times to achieve a range of colours. The process is temperamental, and results can be difficult to control, so gum prints tend to have a painterly quality to them. As such, the process is highly flavoured by experimental photographers. Though gum prints still require careful storage, they are among the most stable kinds of photographic prints.
Dựa trên tính nhạy sáng của ferric oxalate (muối sắt của acid oxalic) và potassium chloroplatinate (muối bạch kim), kỹ thuật cho ra bản in đơn sắc này còn có tên gọi khác là platinotype.
Sau khi rọi, ảnh được hình thành trực tiếp lên sợi giấy nên bản in không có độ bóng như những kỹ thuật sử dụng nhũ tương chứa muối bạc làm lớp phủ bề mặt khác, độ bền cũng vì thế vượt trội hơn, ko bị giới hạn bởi lớp phủ kia mà nhanh chóng xuống cấp. Một đặc điểm quan trọng nữa của bản in platinum nằm ở dải sắc độ rộng, đặc biệt là sắc đen rất sâu, đã chinh phục được những nhiếp ảnh gia huyền thoại như Irving Penn, Horst P. Horst…
(An article from The Photography Collector’s Handbook)