Scratches in your cars paintwork can generally be grouped into two different categories; those that inflict the clear coat only and can be removed with the use of abrasive polish products, and those that have actually gone through the surface clear coat into the color and sometimes even the primer base coat underneath, that cannot simply be polished out. These kinds of deep, severe scratches can actually be felt with your fingernail when drawn over the surface and will require paint and cosmetic repairs in order to completely eliminate them.
These kinds of exterior cosmetic repairs are usually carried out by professionals but there is the option for a DIY repair of scratches depending on your capabilities and level of experience, plus what products & equipment you have access to. The method of repairing deep scratches yourself is actually very similar to how rock & stone chips are DIY repaired and the same principles and methodologies need to be applied.
Firstly, the scratch and surrounding area needs to be thoroughly cleaned, degreased and decontaminated. A diluted all purpose cleaner or traffic film remover are ideal for this as they will also remove any wax or sealant from the surface which is critical for paintwork repairs as it allows the new paint to bond to the surface properly.
Next, you need to obtain a matching pot of touch up paint using the unique paint code of your vehicle. Most touch ups and matching pots come complete with some form of applicator or brush but these are usually cheap and poor quality and are simply too large to be able to deal with an intricate repair. Instead, you should find yourself a fine artists paintbrush too use for the application of the paint. This allows for a much greater extent of control and helps prevent too much paint being applied or a messy job being carried out.
After throughly mixing the paint to ensure a good match is achieved you should carefully begin to apply it using the fine paint brush working the full length or the scratch. Depending on the location of the scratch and whether it is on a flat or vertical surface you can either build up the paint in a number of light layers, allowing the paint to fully dry in between applications, until the level of the paint you have applied is slightly proud of the level of the surrounding paintwork, or, if you are confident and steady handed you can apply the paint relatively generously in order to completely fill the cavity of the scratch in one single application.
Whatever method of application you do choose it is important to let the fresh paint thoroughly cure on the surface – the paint manufacturers guidelines should be followed for this but it is usually a complete 24 hours.
The next stage of the repair is to use a range of appropriate fine grade wet & dry sanding paper in conjunction with a good lubricant and lightly sand over the new paintwork to remove enough material so that it is left at the same level as the surrounding paintwork. You should run your fingertips over the sanded area until it feels perfectly level and no variations in the surface can be felt – even if only very slight.
Once the area has been successfully leveled, it needs to be polished in order to remove the sanding marks and hazing that the wet & dry paper will have left. It should be noted here that a polishing machine (whether rotary or dual action) needs to be used and you should not wet sand any area of your vehicles paintwork if you do not have access to an appropriate machine, as hand polishing alone will not be capable enough to properly remove the sanding scratches and fully restore the area. An abrasive polish product should be used in conjunction with a cutting or polishing pad to initially remove the scratches and hazing and then a lighter finishing, or all in one polish product should be used to fully refine the area and restore complete clarity.
The polishing steps may need to be repeated in order to fully remove the wet sanding marks but once completed you should be left with a clear, clean and glossy surface and you should not be able to tell where the original scratch was.
The final step would be to use a synthetic sealant or a natural carnauba wax to thoroughly protect the area, lock in the new finish and to also help match the gloss and shine of the newly repaired area with the surrounding paintwork or panel. The keys to ensuring you get a car scratch repair like this right are to make sure that the area is thoroughly cleaned and decontaminated prior to applying any paint, to make sure you source an exact matching paint and most of all to simply take your time and not rush on to the next stage prematurely and jeopardize the work you have just carried out.
As has previously been mentioned, you should only really undertake this kind of car scratch repair if you have access to the right kind of products and equipment and only if you are completely confident in your abilities to carry it out, otherwise you may well end up actually making it look allot worse that the original scratch did. This is however, a highly effective, and relatively quick, cheap and straight forward approach to car scratch repair and can produce professional quality results when tackled correctly.