When you want a weathered, rusty, "been in the elements" look, PaperArtsy's Rusting Powder will give you just that. It's best used on porous surfaces such as paper, fabric, chipboard, etc.
There are 2 application options: lightly adhere the powder with adhesive or gel medium, being sure to not cover all of the powder with the medium, or just sprinkle it on the surface without an adhesive. Spritz with water and allow the rusting to begin. Or use white vinegar/lemon juice which will cause even more rust effects. The process can take some time. You may need to add more liquid to force the reaction. Once you’re satisfied, brush away the loose powder.