My Experience with the Stanley Gibbons Spectrum Watermark Detector
For someone who isn’t a big fan of dealing with watermarks, this detector — while imperfect — is a nice tool to have on hand. I got this about a year ago, and it is my go-to when I’m dealing with watermarks. I’ve used lighter fluid once or twice, and I have read about other, more inert fluids that are available…I’d still like to try those as well.
The detector consists of a housing with multicolored LEDs, a thick pane of transparent acrylic, and a thumbscrew with a piston that acts as a vice. The stamp goes under the acrylic, and the thumbscrew is tightened — compressing the stamp between the acrylic and the piston. The light is then passed through the acrylic which makes watermarks evident.
The SG Spectrum Watermark Detector
From the front you can see two dials. The top dial controls the intensity of the light (sort of like a dimmer switch) and the bottom turns the lighting on and cycles through a few different colors. In my experience so far, the green light works the best.
The side and back views of the detector
From the side you can see the thick acrylic, which is compressed against the piston moved by the large thumbscrew on the back. The acrylic slides out like a drawer to allow the user to slide a stamp or two under the acrylic before sliding it back into the device, and subsequently tightening the thumbscrew. Then you can view the watermark (or lack thereof) via the different colors and intensity of light.
Below are two stamps from Finland (just because that was the country I happened to be working with when I pulled out this detector and considered writing about it). One is watermarked, and one is not. If you hold the watermarked stamp up to the light just perfectly, you can sort of see one, but it is not clearly evident.
Which is the watermarked example?
Here are both stamps under the acrylic with the green light — you can see the stamp on the right was made during a period when Finland was using a swastika as a logo for their military, so there is a swastika watermark. (This is actually a really interesting little bit of history that I had never known about prior.) The stamp on the left has no watermark evident under the light.
I’ve noticed a few limitations with this device. It without a doubt works best on mint never hinged items. Hinge remnants, for instance, add some thickness to the stamp and prevent it from compressing the stamp enough to show a watermark. Disturbances in the gum also can obscure a watermark. This is more likely if the watermark is small (as opposed to a repeating pattern like the above) because it doesn’t need to be a large gum disturbance to obscure it. In these instances, watermark fluid might still be a better option.
Curious to hear anyone else’s thoughts and experiences with this.
You can get one from Wizard Coin Supply.
Andrew has been collecting since 2020, and created this website in 2022 to document his philatelic experiences.