The spray paint can is technically called the Painter Tool, and it can be loaded with any number of metadata settings—everything from color labels and flags to star ratings, keywords and custom metadata information, image orientation and rotation, a target collection, and even develop settings based on the presets you have loaded into the Develop Module.
To put Lightroom’s spray paint can to use, first ensure you’re in the Library Module, then be sure you’re looking at your images in grid view (rather than the individual image displayed in loupe view). Do this by clicking G (for Grid) on your keyboard. Next, click the painter icon (the one that looks like a spray paint can below the grid of thumbnail images) and then choose via the adjacent dropdown menu what information you’d like to “paint” across multiple images. Maybe you want to label a bunch of images red. Or perhaps you’d like to apply your keywords and copyright to a group of images selected for publication. Or maybe you simply want to quickly flag for rejection a bunch of images that just don’t make the cut. You can click and drag the spray paint can to apply the data to every image you hit, or click on and off to spray them one by one. It’s a quick and easy-to-use tool, and one that makes a lot of sense for us visual types. Give it a try to speed up your organization and editing workflow by spraying data all over a group of images.