Now that we know what a stamp watermark is, let’s talk about how we can detect one. A previous article briefly outlined how you can use watermark detector fluid (see article FAQ-What is a stamp watermark?). Is this the only method available to stamp enthusiasts?
Here are 5 different ways to detect a watermark on a stamp:
1) Not always reliable, but certainly the simplest way, is to hold the stamp up to a bright light with the back of the stamp facing you. In some instances bright light will show through the thinner areas of the paper and reveal a watermark. You can also try laying the stamp face side down on a black surface. The darker background sometimes shows through the watermark.
2) You can dampen your stamp with rubbing alcohol or lighter fluid to make a watermark appear. Does it work? Yes. Should you do this? NO!! Not only could you damage your stamp with these fluids, but breathing in lighter fluid could be hazardous to your health. Both lighter fluid and rubbing alcohol also contain additives that can leave an oily residue on your stamp, or even dissolve certain types of inks.
3) Use watermark detector fluid. Place your stamp face down in a small, black dish or tray and moisten it with a few drops of the fluid. As your stamps absorbs the liquid, the thinner areas will appear darker allowing you to see the watermark**. Watermark detector fluid is cheap, reliable and contains nothing that will harm your stamps. However, it does have a strong odor — nothing is perfect! You can purchase watermark detector fluid online at Arpin Philately.
4) Use a Morley Bright Inst-a-tector. Basically this is a box that you put your stamp in face down. When you close the cover, a transparent envelope containing bright blue ink is pressed against your stamp and collects against the thinner areas of the paper, revealing the watermark. The enclosed ink never actually touches your stamp, so no damage will occur. This device will run you about $35 online, with a replacement ink sachet costing about $8.
5) Use an optical watermark detector. These mechanical devices either run on batteries or can be plugged in. Your stamp is placed inside the box and pressed against an acrylic block and then a light is shone through the block. The refracted light shows up the watermark. Some versions of this device include the SAFE Signoscope and Stanley Gibbons Detectamark. Both can be purchased online and will cost you roughly $200-$400. OUCH!!
**according to Canadian Stamp News, watermark detector fluid can also help you spot a thinned, repaired or creased stamp. Handy, if you want to make sure you’re not being scammed!