The evolution of finishing paints in the automotive sector has meant that, for many years, all passenger cars that are factory-coated do so with two-coat paint systems. Within car refinish, the context is not very different and the trend is to continue reducing the use of monolayer paints. Faced with this reality, the question of whether it can be painted over the varnish or not is common.
The two-coat system provides the vehicle’s color in a first coat of paint, known as the base coat, and the level of gloss and protection in a second through a lacquer or varnish. This second layer is on which the repainting paints are applied when any part of the vehicle suffers damage and it is necessary to paint it, hence the need to clarify whether it can be painted over the varnish.
However, doing so is not as simple as applying the paint and finishing the job, since first it is necessary to carry out a series of tasks and a specific preparation of funds that must be known to obtain a quality result that offers guarantees.
What preparation of funds must be done before painting on top of the varnish
It can be painted over the varnish, but first it is essential to carry out the following tasks and operations of preparation of funds:
Verification of the compatibility between the repainting paint and the varnish. Generally, lacquer accepts paints of a different nature well, but the opposite does not happen, so it is always better to make sure of this aspect.
Initial degreasing of the areas to be repainted, using a cleaner such as TEROSON VR 1O to remove any remaining grease, oil or dirt.
Sanding of the surface to open the pore of the varnish and get the repaint paint to adhere perfectly. At this point, it is essential to take into account the dry film thickness that characterizes repainting paint, since it depends on whether it is sanded more or less fine.
As an example, the following table shows the sanding sequences used in the automotive industry that must be given to guarantee the correct covering of the scratch caused, depending on the repainting product used:
Removal of residual dust from sanding by blowing with compressed air. The presence of dust on the painted surface reduces the adhesion of the overcoat paint and worsens the finish, as it tends to leave a surface with inclusions of dust spots.
Masking of all annexed and contiguous elements that should not be painted to protect them from any type of spraying or involuntary application of paint. In addition, when painting vehicles, all gaps must also be sealed in order to prevent paint from seeping through these openings into the various components.
Degreasing of the surface to remove any remaining dirt, grease or oil that may have contaminated the repainting surface. To do this, you should always use completely clean rags or paper and a degreaser such as TEROSON VR 10.
Cleaning the small dust particles that may remain on the surface by wiping with a dust-catching cloth.
Once these operations have been carried out thoroughly, you can paint on top of the varnish. To do this, the chosen product or paint must be applied following the manufacturer’s instructions regarding mixing ratio, dilution, etc., as well as an optimal painting or application technique.
It can be painted over varnish, whatever the type, because this product has adequate chemical resistance that allows repainting. However, before proceeding with this, it is absolutely essential to carry out a primer preparation that ensures and guarantees the total adhesion of the product or paint on said varnish, using the appropriate means of prevention.