Washington Type 1A Or Type 5?

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How do I tell the difference between intalgio and offset printing?

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Distinguishing Offset Stamps

The key to separating offset from rotary and flat plate is to realize that the offset stamps were not engraved. This means that the ink lies flat on the paper of the offset stamp. If you hold the stamp at a very sharp angle to a light source, the color on the stamp will almost disappear. This is just the opposite for the engraved stamps. In fact, one way to tell if a U.S. stamp is genuine and not a reproduction, is to perform this test. All engraved U.S. stamps will clearly show raised ink when held at a sharp angle to light. The offset method of printing also resulted in some very poor quality stamps. In many cases a stamp can be identified as offset just by looking at it, the color and printing quality are that poor.

Sometimes visual inspection is not enough and another method of determination must be made. Since the offset method does not employ engraving, the stamp feels flat. Some collectors can feel the lack of engraving by merely running their fingers across the stamp. A semi-soft nib may be ran gently over the surface, particularly in the area of several parallel lines. This must be done very carefully in order to not scratch the ink from the stamps surface or damage the surface of the stamp in any way. Another favorite method is to use a piece of aluminum foil, or other thin foil, the thinner the better. Place the foil over the stamp in question and rub your finger very gently over the foil. The frame of the oval portrait and other details will show on the foil on flat plate and rotary stamps, but will not show on the offset stamps. Again, care must be taken not to damage the stamp by rubbing too hard. Gentle pressure should bring out the features on the engraved stamp. Practice these techniques on some of the more common varieties and you will soon be an expert at separating engraved and offset stamps.