As neither oil paint nor acrylic paint (also Gesso) adhere well to metal, the panel should first be treated with an adhesive primer or wash primer for metal. This is an industrial product that you can buy in a hardware store. After drying, lightly sand the primer. If the metal can then be seen through the layer, apply a second layer and sand this one lightly after drying as well. For optimum adhesion of the final paint, a layer of Gesso should be applied on top. The preparation is now suitable for both acrylic and oil paint adhesion.