How to Apply a Urethane Basecoat

Posted: May 27, 2014 By: Louis Beaudreau

When you are painting the body of any type of vehicle, you want the best kind of materials to get the job done, particularly when it comes to applying the basecoat. It is important to make sure that you are using your tools in the most appropriate and professional way possible to achieve the best results. In this tutorial, we teach you how to properly apply a urethane basecoat to your vehicle body.

Step #1: Spray Gun Setup

The first step to applying any urethane basecoat is to make sure your spray paint gun is set up correctly. Depending on the type of spray gun you use, there are different rules to follow. If you are using an HVLP spray gun, you will want to make sure that you have a fluid tip of between 1.2 and 1.4 mm and that you set the spray pressure to between 25 and 30 psi. If you are using a Conventional Gravity spray gun, you will want to make sure that you have a fluid tip of between 1.2 and 1.5 mm and that you set the spray pressure to between 40 and 50 psi. If you are using a Conventional Syphon, you will want to make sure that you have a fluid tip of between 1.3 and 1.6 mm and that you set the spray pressure to between 40 and 50 psi. Once you have appropriately set up your spray gun, it is time to start applying the urethane basecoat.

Step #2: Application and Cleanup

First, pour some of the urethane basecoat into your gun paint cup and attach the cup to your spray paint gun. Now, point your gun directly towards the area of the body you want to paint, about six inches from the surface, and firmly hold down the trigger to release a fine spray. Apply the urethane basecoat in two full medium wet coats with a 50% overlap pattern between each one. Wait five to ten minutes flash time between each coat; the flash time should increase if more than two coats are being applied. Most colors will cover the area sufficiently in two full coats, but you can add an additional third coat to set an even metallic pattern onto the surface area by spraying the paint in faster passes from farther away. The entire basecoat should dry dust-free within about 10 to 20 minutes. You can lightly dry sand the area after 20 minutes, but wait at least 30 minutes before wet sanding and 45 to 90 minutes before taping on the fresh film. Also, wait at least 30 minutes before topcoating or clearcoating the surface as applying more coats too soon can cause surface wrinkles. Keep in mind that if you need to recoat any area, reapplying urethane basecoats must be done within 18 hours. If it has been more than 18 hours, abrade the surface with a 400 to 600 grit sand paper before applying any additional coats.

Immediately after you have applied each basecoat, make sure that all of the containers you used are sealed tight to keep the contents fresh for their next usage. Also, remember to properly clean dry your spray paint gun with a suitable gun wash or appropriate solvent. Once all of your equipment is properly cleaned and stowed away and the coats have dried, you will have successfully applied a urethane basecoat to the body of your vehicle.

To learn more about basecoats and for more DIY car tutorials, be sure to visit Eastwood.com.

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