Sooner or later, as one gets deeper into collecting, watermarks that appear not to be listed in the catalog at hand are found. As an example, one occasionally comes across on stamps of the Australian States with watermarks that consist only of a vertical line or are composed of double-lined letters. These watermarks are from the sheet margins of the paper on which those stamps were printed. These watermarks are mentioned in various foot notes that seem randomly scattered through that country's listings.

It would be nice if Scott would duplicate these notes with their watermark listing at the beginning of the respective countries; but as of this writing they do not so you have to look for them. Many collectors feel that these odd watermarks are the result of a printing error wherein the printer did not place the paper in the press correctly. Personally, I don't think these watermarks are errors at all. I think they are due to salvaging operations at the paper plants. Watermarked paper, by its nature, was an expensive material compared to plain paper. I feel that the paper plants cut as many sheets of paper out of their production batches as they could; and if this meant that the paper maker's watermark or the border watermark was aligned too far from the edge, I don't think they or the printers lost too much sleep over this minor lack of perfection.

Regardless of how these variations came to be, they are not all that common. They are collectible and some specialists pay a premium for them. Like all oddball stuff, they have no extra value to the collector unless they can find someone who is willing to pay a premium for such material. They are, however, a nice little extra to add color to your collection when you come across them.

If you are having trouble separating one watermark from another and need a reference copy that will last for awhile, there is one trick that I have found rather useful. Look for a stamp that is found only with that watermark. Place a very small drop of mineral oil on that stamp and place it upside down in a black-backed mount. Perform this operation away from your collection and use no more mineral oil than necessary or you will have it all over the place. This operation will make the watermark visible for a long time without using up a lot of watermark fluid. Mineral oil does evaporate but at a very slow rate. It will wreck some stamps; but for most, it will leave them as they were after a few weeks in the open air in a warm place.

Handle the mount with the stamp and the oil in it with a special set of tongs and keep it away from your album. With a little practice, you may find this a great help when separating watermarks. Using a whole mount strip, you can do each of several watermarks all next to each other for easy comparison.