Most shipping containers are made of steel and are available in many shapes and sizes. Some containers are large enough to carry cars and trucks, while others are the size of a shoe box. Painting a shipping container to identify it or with a logo requires preparation. When painting steel, it is important to remember that the surface must not be so smooth that the paint won't stick to it.
Take the container apart, if you can. With a large container, this may not be possible, but smaller containers may be easily taken apart.
Clean the container inside and out with a rag dipped in a mixture of water and mild detergent. Remove all debris and dirt. Rinse the container and dry it thoroughly.
Sand the container down over every part you wish to paint with a 120- or 150-grit sandpaper or sanding sponge. Use firm pressure and rub with the grain of the steel.
Wipe down the sanded container with a tack cloth to remove sanded dust.
Paint the steel with a coat of an oil-based, rust-resistant primer made for steel. Follow the manufacturer's instructions and allow it to dry accordingly.
Paint a final coat of high-gloss, rust-resistant enamel according to the manufacturer's instructions. Let the final coat cure for at least 12 hours or the time recommended by the manufacturer.
Reassemble the container after the paint is dry.