Place a 2-foot section of copper wire in a plastic bucket and top with 2 ounces of muriatic acid. The acid slowly breaks down the copper, which creates a solution that rusts nearly any type of metal. Wear rubber gloves when handling the acid solution. Leave the mixture in the bucket for at least two days.
Pour the acid solution into a spray bottle. Arrange a canvas tarp under your furniture and spray the acid solution on the piece. After coating the metal surfaces with the acid, let the furniture sit out overnight. The longer you leave the acid solution on the furniture, the more rusting appears.
Wipe the furniture down with a damp cloth, removing any of the acid solution from the chair. Wipe the piece off once you achieve the rusted look you want. Dry the furniture off with a dry cloth and lightly sand, removing any rust debris left on the piece.
Apply an even coat of your first paint color to the silver furniture. Sand the piece with a sanding block, once the paint dries, which lets some of the rust show through. Apply a second coat of the first paint color and sand again.
Paint your second paint color over the first paint color. Wait until the paint dries and lightly sand the piece with the sanding block. Paint a second layer and after that coat dries, sand again. Each time you sand the furniture, you peel away the paint, which lets other layers show and gives the piece that vintage look.