The other day I toured a manufacturing facility, which is always a thrill for me—I love to see how interesting things are made.

I was there to observe how the site communicates and make suggestions for improvement.  And right away I noticed that this organization uses three kinds of workplace communication: old-fashioned cork bulletin boards, posters and electronic screens.

I have ideas about all three, but today my focus is on posters. The best posters can be very effective; after all, they have the same attributes as outdoor advertising. Posters attract attention, because employees are likely to notice them as they walk by. And like a billboard, a poster can quickly convey a key message.

But posters aren’t foolproof. The first challenge is where to put them. Posters are sometimes hung in quiet corners where no one ever goes or in busy corridors where employees rush by without seeing them. Effective placement requires you to observe how employees behave and make sure posters are hung where people will see them.

The second challenge is more acute: Posters lose their potency very quickly. On the first day a poster is hung, everybody notices it. By the end of the first week, the poster has become stale. If a poster stays up for weeks (or even months), it becomes wallpaper: a familiar pattern that fades into the background.

The remedy? Treat posters as disposable. Give them a “sell-by” expiration date that’s more like bread (days) than canned beans (years). And when a poster’s time is up, put up a new one. That way, your workplace communication will always be fresh.