That's a fantastic project! Giving old trash cans a makeover is surprisingly satisfying and practical. Here’s a natural, step-by-step approach I'd take based on what has worked for me and many others.
First, give them a deep clean. This is the most important step. Mix warm water with a strong degreaser or dish soap. For stubborn grime, a paste of baking soda and water works wonders. Scrub every surface, inside and out, with a stiff-bristled brush. Don't forget the lid! Rinse thoroughly and let them dry completely in the sun. If there's rust, use a wire brush or sandpaper to scrub it off until you see bare metal.
Next, consider a fresh coat of paint. It makes the biggest visual impact. Use a spray paint specifically designed for metal and outdoor use. Lightly sand the entire can to help the paint adhere. Apply 2-3 thin, even coats, allowing proper drying time between each. A neutral black or dark green is classic, but a bold color can add personality to your alley or curb space. For a professional touch, use a small roller for the body and a brush for hard-to-reach spots.
Finally, add protective details. Once the paint is fully cured, consider applying a clear sealant for extra protection against weather and scratches. You can also use a permanent marker or stencil to neatly re-label the cans (TRASH, RECYCLING) if needed.
The key is in the prep—the cleaning and sanding. A little effort here makes the painting last so much longer. Your renewed bins will not only look great but will also promote a cleaner feel to your urban space. Good luck, and have fun with it