Recyclable, Compostable Stamps That Last “Forever” FPL and the U.S. Postal Service build on their 20-year partnership


Recycling-compatible stamp using FPL-developed pressure-sensitive adhesives.

Do you remember the last time you licked a stamp? Maybe not, and for good reason: 20 years have passed since the U.S. Postal Service (USPS) first started transitioning from “lickable” stamps to the peel-and-stick squares we use today, called “pressure-sensitive adhesive” stamps by those in the know.

FPL worked closely with the USPS throughout that transition, and in the two decades that have followed, to continuously improve stamps.

The earliest cooperative research between FPL and the USPS focused on developing pressure-sensitive adhesives that didn’t gum up the equipment used to recycle paper. By developing an adhesive that was compatible with the recycling process, an additional 20 million tons of waste paper can be recycled each year.

This research project ended up reaching beyond just stamps, according to Carl Houtman, a chemical engineer at FPL. “Advancements made with the Postal Service work were of interest to the entire label industry,” explained Houtman. “The Tag and Label Manufacturer’s Institute has adopted the same standards as the USPS, so labels can now be certified as recycling compatible.”

foreverstampsToday’s work with the USPS is two-fold: improving stamp performance continues to be a priority, as well as reducing the environmental impact of stamp materials.

The introduction of the Forever Stamp has kept researchers busy developing improved performance and accelerated aging tests to ensure that the stamps indeed remain useful, if not forever, at least close enough to qualify for the name.

FPL research materials engineer John Considine conducts accelerated aging tests using a chamber and meteorological data from various locations in the United States. Considine can subject stamps to rapid cycles of heat and humidity, mimicking conditions the stamps might have to tolerate in the real world.

Houtman’s work, on the other hand, focuses on developing new pressure-sensitive adhesives that are environmentally friendly by looking at three key areas in the lifecycle of the product.

“We’re developing adhesives that are made from renewable resources,” Houtman says. “Additionally, we want the materials to be compatible with the recycling process and also biodegradable if they are thrown away.”

Houtman is also developing experimental methods for determining the biodegradation rate of new materials. Currently, test samples are placed in a sludge inoculum that contains organisms that degrade, or “eat,” the sample. The biodegradation rate can then be determined by measuring how much oxygen is consumed during the process.

Research and development will continue as FPL and the USPS work together to build on the successes of the past 20 years. And while stamps aren’t something most of us give much thought to, perhaps next time you use one you’ll at least be grateful that you don’t have to lick it.

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By Rebecca M. Wallace, FPL Public Affairs Specialist