Painting metal is a simple step by step process: Choosing the right product will give you long-lasting results. There are specific paints designed just for metal; some metals can be painted with latex paint, and some must be painted with oil-based paint. Any metal prone to rust should be painted with oil-based paint, as this will not allow moisture to come in contact with the metal. Radiators require designated radiator paint.
1 Remove rust and clean the metal surface: Use steel wool to sand the rusted area smoothly, as steel wool helps remove rust. Use a dry cloth to wipe off residue after you have smoothed the rusted areas.
2 Apply an oil-based primer on the areas that you have sanded. An oil-based primer will seal the rust and prevent it from coming back through your paint. Allow the primer to dry before painting completely. Most oil-based primers dry within 2 hours.
3 Prime the entire surface if your paint requires it: Most paints need primer as a bonding agent, or a surface that the paint can adhere to. This is not always necessary; there is a paint that can be directly applied to bare metal. This paint is known as paint on metal. It is a very strong paint and can be purchased in brand name paint stores.
4 Mix a small amount of paint thinner into your paint; do not use water to attempt to thin oil-based paint. Stir approximately 1/3 cup paint thinner into 1 quart of paint: Paint thinner will allow oil-based paint to be applied in a smooth and even manner. Oil-based paints become tacky very quickly, and when that occurs, you cannot brush or roll back into it; paint thinner eliminates this problem. It is usually not necessary to thin your primer.
5 Brush on the oil-based paint, using a good-quality paintbrush in areas that you cannot use a roller. Use foam roller pads on larger areas that can be rolled. Foam roller pads will create a finer finish when using oil-based paint.
6 Use an airless sprayer as an alternative to brushing and rolling. Oil-based paints can be sprayed just as effectively as latex paints: It is not necessary to thin the paint if you are going to spray it. Clear water from your airless sprayer hose before try to spray an oil-based paint, or your sprayer will clog up. Thoroughly clean your sprayer after using an oil-based paint.
Most aluminium and galvanized metals can be painted with latex paint, although it is best to use oil-based paint on steel. Oil-based paints keep rust from forming. Touch up your paint job periodically. All paints will chip or peel if you do not touch them up.
For painting radiators, it is best to use specialised radiator paint: The factory enamel coating is designed to produce optimum heat, and the more non-enamel paint you put on, the less performance you will get from your radiator. One should never put undercoat or gloss paint on; only ever use the paints designed for the correct use.