Understanding the printing processes used to produce postcards can help you describe what you have and will help establish value. Below are samples of various printing processes from postcards scanned at 2400 pixels per inch, so you can see the tiny detail in the grain.
Do it yourself: Once you know what you're looking for, a good magnifying glass will show you what you need to know. A 15x jeweler's loupe will allow an even closer inspection.
An image is printed directly on to sensitized paper from a photographic negative. All view postcards are based on original photographs (using photo-mechanical methods, below) but "real photo" postcards are in a class of their own. As you can see below, photographs are the gold standard in terms of fine grain, providing beautiful, detailed resolution. The film grain is nearly microscopic.Real Photo postcards were often unique images, not meant for mass distribution.
Images were made by rendering a photograph onto a printing plate by various means, for mass production.
Collotype. In full commercial use by the 1870s, this "photo-gelatin" method produced a very fine grain, sometimes indistinguishable from a photograph by the naked eye. Impressions were limited to 1500 to 2000 before the gelatin printing surface deteriorated. They were quite common in postcards. The sample below (from a 1914 French postcard) shows the highly reticulated grain. The Albertype (USA) beneath it is a variation of the collotype.
Photogravure. Introduced in Vienna in 1879, a copper engraving plate was sensitized photographically. They were beautiful, but expensive. And the steel facing of the plate would wear out after about 1000 prints. I haven't seen any postcards from this process. (The sample below is not from a postcard.)
Platinogravure. The sample below is from a French postcard of Lourdes. What do you think? From what I can gather, Platinogravure is a brand name for a French reproduction process. I would have assumed it is a variation on photogravure, but the texture looks screened.
Halftone. Popular after 1894, halftones were produced from a photographic negative processed through a screen onto a grid of variably sized black and white dots. Easy, cheap, not very beautiful because of the relatively poor resolution. (Sample below, from a White Border era postcard, 1915-1930, USA)
7.5.05 (revised 12.6.05, 5.1.13, 10.31.15)
THE SUDDEN SILENCE: A Tale of Suspense and Found Treasure (2015) Thailand: lovers of ancient treasure tangle with international black markets. Delia Rivera pulls Martin Moon back into the game and their quest turns deadly. In paperback and Kindle editions.
TRIBE OF THE BREAKAWAY BEADS: Book of Exits and Fresh Starts (2011) Time after time, Mary asks herself: Do I go or do I stay? She finds her power in her ancestors: Smart women turn discontent into action. An illustrated memoir in paperback and Kindle editions.
PASSION AND PERIL ON THE SILK ROAD: A Thriller in Pakistan and China (2008) The twin forces of revenge and redemption drive Nellie MacKenzie and Taylor Jackson on a crazed adventure into the heart of Central Asia. They grapple with issues of ethics, trust, rage, and bitter heartbreak -- as well as the intrigue of the international antiquities trade. In paperback and Kindle editions.
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