These days, you hear a lot about central banks printing money, from the U.S. to Europe and Japan. In many cases, printing money requires some outside help.

That’s where Fortress Paper comes in. The Vancouver-based firm makes special paper for bank notes with a particular focus on security. As counterfeiters take adavantage of new technology to make harder-to-detect fake currency, treasuries around the world are turning to companies like Fortress for new security features for their money.

“If you think about a piece of currency you might hold in your hand — it could be worth a hundred or a thousand dollars — yet it’s really only a few pennies to produce on a mass scale,” Chad Wasilenkoff, Fortress Paper’s CEO says. “Nobody wants to be the first, or very cavalier — or take a chance on a new security feature, so it’s very hard to get them implemented and adopted.”

But once one country successfully experiments with new security technology, others will quickly follow suit. Wasilenkoff told us about a new feature that took Fortress nine years to develop.

“We take two very thin sheets of bank note paper and we bond them together,” he explains. “Right before we bond them together, we cut holes in each side, and then put molten polymer in the middle. So your bank note can have these transparent, or see-through, windows.”

Wasilenkoff says the special window not only makes the bill more difficult to replicate, it also gives designers more options when creating a new note.