Thin

A thin is a fault in which part of a stamp’s paper has been torn away from the back, leaving that area thinner than the rest. Thins are one of the most common faults and one of the easiest to create accidentally.

How Thins Happen

• Removing hinges — pulling off a stamp hinge that is firmly stuck can take paper with it. This is the most common cause on mint stamps.
• Peeling stamps off envelopes — used stamps pulled from paper instead of being soaked often lose fibres from the back.
• Album contact — gum sticking to album pages in humid conditions, then being pulled away.
• Rough handling — scraping or abrasion.

Types of Thin

• Light thin — small and shallow, visible only under careful examination.
• Heavy thin — a large or deep area of paper loss.
• Surface thin — damage to the face of the stamp, often from scraping or from a stamp stuck face-down.

Detecting Thins

1. Transmitted light. Hold the stamp up to a bright light. Thin areas show as lighter patches.
2. Watermark fluid. Place the stamp face down in a watermark tray with fluid. Thins often appear as dark areas, much like a watermark.
3. Look under hinges. A hinge remnant can hide a thin, so treat remnants with caution when buying.

Repaired Thins

Thins can be filled with paper pulp and sometimes covered with regumming to disguise them. Repaired stamps must be described as such. Watermark fluid and ultraviolet light can reveal repairs, and expert certificates will note them.

Value Impact

A thin is a condition fault. It reduces the value of common stamps to little, and while a thinned rarity may still be worth a good sum, it will be priced well below a sound example. Always check stamps for thins before buying valuable items.