Throughout the morning and early afternoon on Saturday, some very fine and sporadic drizzle landed on the 15th edition of Artpace’s Chalk It Up, held this year on Houston Street and Main Avenue. It was not enough to obscure the dozens of sidewalk and street pieces that had already been created with chalk by featured artists, school art clubs and the thousands of families who walk up and participated—as they’re encouraged to do. Until about 1:30 p.m. That’s when a five-minute downpour wiped away the pieces, or rendered them unrecognizable. There was still 2½ hours left in the event, plenty of time to recreate the art—and some people did continue to draw—but it deflated most of the participants who got started on their works well before the 10 a.m. start time. As is the custom, an Artpace photographer with the help of an assistant positioned a ladder in front of each piece, climbed it and captured the blotches of color. He dutifully took the photos anyway to save something for the record.