How To Apply Car Filler: A Step By Step Guide

ProWorx develops and manufactures an extensive range of car filler products to the professional industry as well as for private use. All ProWorx filler, putty filler, fibreglass filler and plastic fill products are produced to the highest industry standards.

The following is a step by step guide showing how the application of this versatile product range is carried out in a professional setting.

1) Mixing The Car Filler

It is extremely important to mix the car filler product on a proper mixing surface and using plastic applicators. These mixing surfaces come as a solid plastic mixing board or as a board of treated paper. The product is altered when mixed on an untreated board. It impacts the drying times and the quality of the end result.

It is also advised that the panel which the product is being applied to is also heated prior to application for optimum results. This ensures the temperature of the fillers is not altered during the drying phase. This means that the catalytic process within the product happens under optimum conditions.

2) Applying The Mixed Car Filler

Once the product is mixed with satisfaction using the plastic applicators and mixing board it is time to apply the product to the surface. Load in the fillers evenly with the applicator, be sure to layer it on using slight pressure as this will help to push out any air bubbles and lessen the appearance of pin-holes.

Obviously, if you are using the Swift or Pearl products, there is less of a need for this. Build your fillers up a little past the height of the repair and then work the edges in a radius around the damaged area. Your filler should cover a wider area than the initial damage zone.

3) Sanding The Cured Car Filler

When sanding your first coat of car filler, and it will take a series of coats depending on the size of the damage, you will notice any unevenness on the surface. This is completely normal as the filler seeks to fill the cavity. Check the surface by feel to see where the low spots are and where needs further applications.

One trick for this is after your initial skims, is to begin sanding the filler surface and then stop and spray a dust coat of Matt Black aerosol over the surface. Once this dries and you begin to sand again the sandpaper will clean the flat surface area and leave the black on the low point, making it very easy to identify where you need to apply further fillers.

4) Feather Edging The Body Filler

Once happy that the surface is as flat as you can get it, sand out any deep sandpaper marks by moving through successive grades of sandpaper (eg. from 120-240-320 grade). Then you can begin prepping it for primer and paint. To be sure of a proper and professional looking mirror finish on your work, apply a skim coat of ProWorx Silk Glazing Putty car filler. This viscous filler will level out the surface and fill in any pesky pin-holes. It is extremely easy to sand.

Once dry, clean down the surface with 320 sandpaper and be sure the surrounding area and repair run even with each other. Do not to leave any scratch marks or edge unevenness that may resurface after painting, this process is known as feathering.

5) Mask for Priming or Painting

Finally, blow off any dust residue and if possible clean down the surface using a degreaser and tack cloth. Tack cloths are sticky a cloth that helps remove any dust or dirt that may get stuck under the primer and paint coats.

Then simply mask around the area with foam edge tape or masking tape and apply even coats of primer/ paint. Apply a heat lamp to the panel to vastly improve curing time if this is an available option.


ProWorx develops and distributes a range of products for the automotive industry. If you have any queries, please contact our sales team who is happily standing by.


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