Why Israeli Stamp Glue Was Certified Kosher

For decades, Israeli postage stamps featured an unusual certification that most countries never considered: their adhesive glue was certified kosher by Israel's chief rabbis. This wasn't bureaucratic overkill—it was a thoughtful accommodation for religious observance.

The reasoning was straightforward. When you lick a stamp to affix it to an envelope, you're potentially ingesting trace amounts of whatever substances are in that glue. For observant Jews who keep kosher, this matters. Kosher dietary laws don't just cover meals—they extend to anything that might enter the mouth, even accidentally.

What Made Stamp Glue Non-Kosher?

Traditional postage stamp adhesive was often made from animal-based products. The most common culprits were:

• Gelatin derived from non-kosher animals like pigs
• Bone glue from animals not slaughtered according to kosher law
• Casein from milk mixed with non-kosher additives

Even tiny amounts of these substances would render the glue non-kosher. Israeli postal authorities recognized that requiring citizens to choose between sending mail and maintaining their religious practice was unacceptable.

The Certification Process

Rabbinical authorities inspected both the ingredients and manufacturing process of stamp adhesive. They ensured that any animal-derived products came from kosher sources, slaughtered and processed according to Jewish law. Plant-based adhesives were also used and certified to avoid any animal product concerns altogether.

This certification appeared alongside the Israel Postal Company's regular quality control, making Israeli stamps one of the few postal products in the world with religious dietary approval.

The Self-Adhesive Revolution

Israel issued its first self-adhesive stamp in 1996—a joint Hanukkah issue with the United States. These peel-and-stick stamps don't require licking, which eliminated the kosher concern entirely. By the 2020s, most Israeli stamps had transitioned to self-adhesive backing.

The shift mirrors a global trend. Postal services worldwide have moved away from water-activated glue toward self-adhesive stamps for convenience and shelf life. What was once a uniquely Israeli religious consideration became largely moot thanks to technological advancement.

Still, the kosher stamp certification remains a fascinating example of how governments can accommodate religious practice in unexpected places—even on something as mundane as mailing a letter.