No fooling Greene machine

The Vincent Graves Greene Philatelic Research Foundation held an open house April 12 to unveil its latest tool in stamp expertization, the Foster Freeman VSC 6000/HHS video spectral comparator, a specialized tool for examining documents. The comparator consists of a large box with a high-resolution camera equipped with a zoom lens. Once imaged, the document – in the case of the foundation, a stamp or cover – can be examined under various forms of lighting, through a range of filters, and at various wavelengths. The results, which can be printed or saved as a file, are viewed on a massive 75-centimetre (30-inch) screen monitor.

The image can be magnified up to 170 times real size with a staggering resolution of more than 28,000 pixels per inch. Specialized features can be used for examining watermarks, ultraviolet (fluorescing) features, and optical variable devices. During the demonstration, attended by dealers Vance Carmichael, John Jamieson, and Roy Houtby, as well as Canadian Stamp News, Garfield Portch demonstrated the machine with the massive $10 blue whale stamp. Blowing the stamp up revealed microprinting and a number of fluorescing details. Moving up the edge of the stamp, he revealed how the software makes it possible not only to count the perfs, but to actually make measurements.

In a second demonstration, two earlier stamps were compared. Using the comparator, it was possible to backlight the stamps to reveal the laid paper line, and compare details of the wire weave. It appeared identical in both cases. In the case of a cover, Portch showed how it was possible to compare a spectral signature of the ink used in the cancel on a stamp with a separate date stamp. In this case, the inks matched, revealing that both stamps had been applied at the same time. The tool can also be used to analyze inks on two different stamps. Portch said that while members of the foundation are still developing their skills with the device, they have become proficient at spotting removed cancels in a number of cases.

The technique involves a form of side lighting, which can reveal fine abrasions on the surface of the stamp left when the cancel was removed. Of course it remains a tool that must be used with good judgement, Portch said. “What it really is,” he said, “is a new way of looking. The danger is that you can over-analyze things.” Located in Toronto, the foundation was established in 1975. In addition to its expertization service, it maintains a comprehensive library for research and study purposes and supports other projects such as lecture programs and publishing. For more information, visit

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