A thin is an area of paper that is missing from the back of a postage stamp. It generally has a see-through appearance when held up to a light, and often occurs when a hinge is improperly removed from the stamp gum. Some dealers will try to conceal a thin, in order to sell their stamps at a higher price. With a little knowledge and a little practice, you can be assured that you will not unknowingly add a thinned stamp to your collection.
Difficulty: Average
Time Required: 1-5 Minutes
Here's How:
- For large obvious thins, the easiest way to detect the thin is to hold the stamp up to a light source. As the light shines through the paper, thins will show up as translucent areas in the stamp design. Smaller thins, however, will not easily be seen in the light, and should be detected in another manner.
- The best way to detect a smaller thin is to place your stamp in watermark fluid. The thinned area of paper will be revealed as a dark patch on the stamp paper. The deeper the thin, the darker the patch.
- Once you have applied watermark fluid, placing the stamp on a blotter and allowing the stamp to dry, will further reveal the severity of your stamp thin. Thinned areas will appear as white patches on drying stamps, because they dry quicker than the thicker surrounding paper.
- There are instances where gum disturbances and hinge remnants appear as white marks when drying, and they may be mistaken for thinned paper. These will not appear as dark patches when first placed in watermark fluid and should be re-submerged to verify their identity.
- Most older stamp issues have repaired thins. In many cases, thins were filled for appearance sake, and were not meant to deceive. These thins were filled with a pulp-like mixture, allowed to dry, and sanded until the filled area became level with the rest of the surface. While these repairs will not appear when held to a light source, they often are revealed as light areas in watermark fluid. In addition, the use of an ultraviolet light may reveal repairs like these.
- Some thins aren't visible, even when placed in watermark fluid. These include: very shallow small thins, thins located on watermarks, thins opposite cancellations, and thins on orange or yellow high-contrast stamp designs. In cases such as these, you may wish to consult a stamp expert to help you properly identify a thinned area.
Tips:
- Never buy a high value stamp without first observing the stamp for noticeable thins.
- Always ask the dealer if they have a quality guarantee that protects you from fraudulent or repaired stamps. If you later place your stamp in watermark fluid and a thin becomes visible, a guarantee will allow you to return the repaired stamp without issue.
- Be aware of thin concealers. A cancellation may be added to a used stamp to hide a small thin or pieces of hinge may be applied to the stamp gum preventing the thin from being revealed in watermark fluid.
- Always get to know your stamp dealer. Asking your dealer questions, talking with local stamp club members, and looking at your dealer's credentials will help you find a reputable honest seller that won't falsely sell you repaired stamps.
What You Need:
- Tongs
- Light Source
- Watermark Tray
- Watermark Fluid
- Blotter or Drying Book
- Ultraviolet Light (Optional)