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The wet on wet process, as mentioned in the article on the classification of the different types of equipment, is associated with high productivity work, where reducing the time spent on various vehicle repair processes is sought.

Applying the filler paint, as you know, is essential for obtaining a final quality repair. It works as an insulation, preparation and anchoring coat between the lower coats and the finish paint. In addition, the correct choice of filler shade optimises the colour matching of the intermediate coat and the finish paint.


    The filler application process, including the preparation, application and sanding phases, can vary substantially depending on the repair system you choose, the type and size of the part or the complexity of the repair.

    Here, we will focus on the most frequent uses of wet on wet filler paint, the advantages of this system, and the aspects to consider during its application.

    En este contenido nos vamos a centrar en los usos más frecuentes de la pintura de aparejo húmedo sobre húmedo, ventajas que puede aportar este sistema, así como los aspectos a tener en cuenta durante su aplicación.

    What is the wet on wet process?

    Very briefly, the wet on wet process is based on applying the filler paint to the surface to repair, with no need for subsequent sanding.

    Wet on wet filler can significantly impact certain repairs at the bodywork and paint shop, its main aim being reducing working time, increasing productivity and improving the flow of repairs.

    El aparejo húmedo sobre húmedo tiene una incidencia destacada en determinadas reparaciones dentro del taller de chapa y pintura, con el principal objetivo de reducir el tiempo de trabajo, aumentar la productividad y mejorar el flujo de reparaciones.

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    Aspects to consider

    This type of filler paint can work as an excellent anchoring coat for finish paint. It has a satin, regular and uniform final texture.

    For a correct behaviour of the wet on wet filler, it is essential to previously degrease and clean the surface thoroughly.

    Make sure to remove any substance from the surface to favour the anchoring of subsequent coats, as there is not much room for correction as with other filler processes, since there is no subsequent sanding of the surface.

    Another essential factor to consider with wet on wet applications is to always follow the indications provided in the technical data sheet on the number of coats and thickness of the coat to apply, and the established drying times. An example of this product category is BESA-WET, an easy-to-apply wet on wet filler, designed to optimise repainting time and use of booth, which provides excellent adhesion on cataphoresis and other types of parts.

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    Frequent applications of wet on wet filler

    Painting of new parts

    One of the most common uses of wet on wet filler is its application on new parts with cataphoresis.

    This process requires to first thoroughly degrease and clean the part with a degreaser and a clean cloth, removing any type of surface impurity.

    After this, the part is ready for the filler to be applied. Sometimes, sanding or tinting of the surface may be required. It will depend on the part’s cataphoric quality, and it will be the professional who will prepare this before applying the filler.

    Follow the technical indications of the product on the number of coats and thickness to apply. Apply a thin, uniform and extended coat that is not too thick to prevent any possible painting defects later.

    Then, once the established drying times have elapsed, apply the finish paint directly, without sanding the filler.

    This will help reduce repair time and consumables used in this type of application.

    Painting of interior areas

    A common practice when painting vehicles during their manufacture is distinguishing between exterior and interior finish areas of parts, such as bonnet interiors, door interiors or engine compartment.

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    The shades and finishes (solid, matt, satin) of these interior areas differ from the finish of the visible areas of the body. This is so to reduce costs and product consumption.

    The use of wet on wet filler for this type of area can be very profitable and productive, reducing repair times, and offering good anchoring for subsequent coats and insulation of lower coats.

    What are the advantages of wet on wet filler?

    • Less time spent on masking border areas: you can use a single mask, both for the filler process and for colour application.
    • Shorter drying time: depending on the drying time established in the product’s technical data sheet, you will be able to apply the finish paint directly.
    • Suppression of the sanding process: this also means no time spent on sanding. In some cases, you may have to sand a small part of the surface, in order to further optimise the anchoring of the finish paint.
    • Use of less material during the repair: use of less masking tape, paper and plastic and sandpaper for sanding, or degreasing agents to clean the surface.
    • Increase in workshop productivity / opportunity cost: reducing the time vehicles stay means increasing the workflow in the workshop.
    • Energy consumption and expenditure is also shorter, as there is no more drying time when using the application booth or via infrared equipment.


    As we have seen, the wet on wet process can help to increase the productivity and profitability of repairs in the workshop.

    It will be you, as professionals, who will have to assess its application and use, which will be conditional on several factors such as the type of part to be treated or the type of repair to achieve.