Cobwebbing Problems in Car Painting

The effects of cobwebbing during automotive paint processes can be highly frustrating and often result in work having to be refinished a second time. Establishing full control over spray guns, and developing a better understanding of the materials you work with, can help to eliminate cobwebbing problems instantly. Before painting begins, it is always advisable to check the setup of tools and viscosity of materials to reduce the risk of cobwebbing.

Spray Guns

Modern base colors are much thicker than those used in the days of cellulose and enamel paints, and it is vitally important that the correct type of gun is used. High volume, low pressure (HVLP) spray guns have adapted chambers that help to promote an effective flow of material. However, cobwebbing can still occur if the gun is not set up correctly. Always refer to technical data sheets to be certain the correct fluid tip and air cap is being used, and ensure the gun needle is sufficiently wound out to let paint atomize correctly,

Materials

Most modern body shops use waterborne color systems that are subsequently covered with a protective clear coat. Colors and clear coats have to be activated before use to the correct mixing ratio, and this information should always be clarified using a technical data sheet before painting begins. Hardeners and activators are added to paint materials to speed up drying times, but reducers are just as important. By adding the correct amount of reducer, the paint will be thin enough to pass through the air cap of the spray gun easily and this will reduce the risk of cobwebbing.

Spraying Temperatures

Professional sprayers enjoy the benefit of low-bake ovens that also provide an optimum spraying temperature while the vehicle is being painted. If a car is being refinished outside or in a workshop, high temperatures can cause paint to atomize too quickly and cobwebs are formed before the paint has a chance to adhere to the auto body panel. If a vehicle is being painted in a normal workshop or outside, it is advisable to avoid spraying during the warmest part of the day. Instead, try to refinish the vehicle earlier in the day or later in the evening.

Painting Techniques

Cobwebbing can occur if the wrong painting techniques are used. Ideally, a spraying distance of 4 to 6 inches should be maintained at all times. Hold the gun too close to the auto body panel and runs will occur. Hold it too far away and the paint can begin to string before it reaches the vehicle and this results in an ugly and unwelcome cobweb effect.