How to use water-based auto paint

paint chart image by Christopher Hall from

Using water-based auto paint for your vehicle is a method of achieving beautiful auto body finishes while using a product that's slightly more environmentally friendly than other paint types. Though growing in popularity, using water-based auto paint has its difficulties.

Water does not carry pigments as well as solvent-based paints, meaning you'll need a slight adjustment in spraying equipment used. Water-based auto paints also take longer to dry, increasing application times as well as increasing the chances of surface contamination during the drying cycle. Once you've accounted for the differences though, the results of a good water-based paint job are as spectacular as those you can obtain from traditional paints.

Mask off the car sections that you don't wish to paint using plastic and masking tape to avoid overspray of painting materials. Remove the existing paint from the vehicle with paint stripper. Brush the stripper over the car and wait as the paint lifts from the car's surface. Wait time will vary according to stripper used so consult the instructions for recommended manufacturing timings. Remove the stripper and loosened paint with a rubber putty knife to avoid scratching the metal. Repeat the stripper application if necessary to remove all paint and primer present.

Remove the masking tape and replace it in case the paint stripper soaked into the older tape.

Clean the metal of the car with a pH-neutral cleanser and a scrubbing pad to remove all stripper residue. Rinse with clean water then pat dry with cloth. Wipe the surface of the metal with cloth dampened with rubbing alcohol and then wipe the car dry with paper towels. Replace the masking tape again.

Remove any scratches or gouges from the auto body by sanding the metal smooth with 400-grit sandpaper attached to an orbital sander. Wipe away the residue left from sanding with a piece of cloth. Clean the sanded surface with a pre-primer metal cleaner then pat the vehicle dry. Change the masking tape again.

Spread the primer coat evenly over the car body with a paint sprayer. Use three thin layers to build up the primer coat, allowing the primer time to dry between each layer. Prime the edges of each section first, and then move from the edges towards the centre, working in 50 per cent overlapping rows to ensure even coverage.

Keep the nozzle of the sprayer between 20 to 30 cm (8 to 12 inches) from the car surface and always pointed directly at the car, moving your arm to provide coverage rather than changing the angle of the spray by moving your wrist. Sand the primer smooth with 600-grit sandpaper and wipe the surface down with a tack cloth. Replace the masking tape.

Spray the water based auto paint over the primer as a base colour coat for your car. Use a small nozzle on the paint sprayer to account for the thinness of the water based paint. Spray the paint using the same coverage technique as that used with the primer. Use multiple layers of the paint to build up an even coating, and allow each layer 45 minutes drying time before applying the next. Allow the final layer overnight to dry and then change the masking tape. Wipe down the car with tack cloth to remove any dust particles.

Cover the basecoat with two layers of clear coat to serve as a wear layer protecting the colour paint. Use the same application process used for the application of the base coat for even coverage. Allow 10 minutes drying time between coats.