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If handwriting analysis should fail, the experts turn to tests of paper, ink and pens, such as those carried out by the West German Federal Archives last week. Here, too, experience and a keen eye for detail may prove sufficient to detect deceit. Benjamin notes that in the West parchment was used exclusively until about the year 1150. Next came two types of rag paper. One was laid paper, formed by being stretched across wires that left visible lines spaced about an inch apart. It was in common use until about 1800. The other was wove paper, in which the fibers can be seen by the trained eye. It was used consistently after 1800. Benjamin has seen only two authentic autographs by George Washington written on wove paper. By 1860 wood-pulp paper, easily distinguishable from rag paper, became commonplace. Many a period piece forger has given himself away by using the wrong paper.
The experts' suspicions can be aroused even by the size of writing paper, since fashions here have also changed through the years. There have been customs too in how letters are folded. Watermarks placed in paper by manufacturers are carefully catalogued and thus can be traced to their origins. The wrong watermark can disclose a forgery. Benjamin and other analysts check the ink used on antique documents. Sometimes its very color is all they need to see. Ink made of ground carbon was used until 1020; it does not affect the color of the paper as it ages. But iron-gall ink, widely used until about 1860, is acidic and with time tends to tint and wear through the paper. Aniline ink followed; it disappears when the paper on which it is used is dunked in water. That is not a test many analysts try, since their document, real or fake, might vanish.
Benjamin recalls one collector of rare autographs who verified, wholly by accident, that his priceless document containing the signatures of all 56 signers of the Declaration of Independence was genuine. A hurricane had caused the paper to be submerged in water for five days. When he retrieved it, the owner found to his relief that all the signatures remained clear and bright. They had been written with iron-gall ink on rag paper.
The type of pen wielded by a forger can be a giveaway. The quaint quill was used exclusively until 1780, when its successor, the steel pen, came into existence. The difference in writing between the two can be seen under a microscope. Fiber-tipped pens were not used extensively in the U.S. until 1964. Any forger using a pen not common in the period his document purports to derive from risks quick discovery. The modern proliferation of pens, particularly ballpoints, complicates the task of current document analysts, but can provide fresh clues. A ballpoint requires the writer to exert more pressure; the force with which individuals habitually attack their writing is often distinctive.
Researchers at West Germany's Mannheim University have applied modern technology to detect minute variations in pressure applied to paper by writers. They are developing an electric grid microscope to measure precisely the