Types Of Watermark Detector
There are currently 4 different types of watermark detectors that can be used:
1. Watermark fluid - The video below demonstrates how to use watermark fluid. The watermark fluid is specially designed not to harm the stamp. The fluid is put in a watermark tray (which is black) and the stamp is placed in the tray with the fluid. The watermark then becomes visible, because the stamp becomes translucent. Once the stamp is dried properly it can be placed back into the stamp album. Modern watermark fluid is safe both for the user and the stamp, but the formulation means that it may evaporate very quickly. Which can make it difficult to see the watermark for more than a few moments.
2. The Morley Inst-A-Tector and Roll-A-Tector use the fact that where the watermark is on the stamp the paper will be thinner. These use a clear plastic pouch filled with blue ink that is pressed against the stamp. The blue ink settles in the areas where the stamp is thinner thereby revealing the watermark.
3. A recent method is to use a computer scanner to scan the stamp against a black background into a computer. Graphics software is then used to enhance the image to reveal the watermark. This is not always that successful.
4. The final method to detect the watermark is to use a Safe Signoscope. In this method the stamp is placed on clear plastic block and pressure is applied while a special bright light is shone through to reveal the watermark. Signoscopes are expensive, and the bulb they use needs to be replaced.
For most people a combination of watermark fluid and the Morley products are the way to go, because the Morley products are successful in most cases, and where they aren't the fluid can normally be relied on to reveal the watermark.
A watermark detector needs only be used where it has been noted that a stamp has either different watermarks, or some copies have a watermark and others don’t. A stamp catalog or album will let you know if this is the case. As noted above, a watermark can make a big difference in the value of a stamp, and this is why a watermark detector is an important tool for a serious collector.