While the venerable Park Slope Civic Council’s “buy local” campaign, which will kick off on November 13 interests us, what absolutely fascinates us is a brave social experiment that will accompany it. The group is buying umbrellas that will be left in stores that people can borrow for use when it’s raining on the presumption that they’ll return them. The yellow umbrellas are a marketing tool for the Civic Council’s Buy Local campaign that will say “Buy in Brooklyn, Shop Local in Park Slope” and have the group’s logo. Stores that want them will have them available to customers, who can borrow them when it’s raining and then return them to a participating store. The idea is similar to “community bicycle” programs in Holland and other countries in which bicycles that can be borrowed for use and returned. (The more successful big city programs, however, generally include cards with computer chips and other tricks to help encourage honesty.)

The Civic Council is spending about $2,000 to buy 400 umbrellas, and there will be some signs that say “Please enjoy this community umbrella and return it to a participating local merchant.” The yellow color is intended to make them stand out. As for the important buy local campaign in Park Slope, which retains large numbers of community-based merchants, we will note that the standard rule of thumb is that every dollar spent with a local merchant is recirculated in the community three times.

The brave social experiment with the umbrellas, however, raises many fascinating questions: Will Park Slopers return the umbrellas? If not, how long will it take for the umbrellas to dwindle, if not vanish? Will Slope residents be hiding schwag umbrellas in their apartments and condos? What will a visiting person from, say, Carroll Gardens or a far off place like Bay Ridge that needs an umbrella do? And, of course, which Brooklyn neighborhood would host the most successful community umbrella program in terms of them being used and returned?

We should have a sense of all this in a few months.