The Basics Of Swirl Marks And Removal Techniques
If you look at a cross section of clear coat paint, you will see three basic layers of paint on the bodywork of the car - the base coat, the colour coat and the clear coat:
If for example you get a deep scratch in your paint, you may see a different colour of paint revealed - this means you have scratched down through the colour coat and into the base coat at which stage machine polishing cannot remove the scratch.
What Are Swirl Marks?
If you look at your car under a bright light, for example sunlight, sometimes you may see very thin scratches in the paint. Here is a picture of what quite severe swirl marks look like:
These tiny scratches are catching the light in a way that it masks the colour underneath and you don't see it. This robs the paintwork of its true deep colour. Shown below is a single swirl/scratch mark in the clear coat of paint.
The sharp edges of the swirl mark are catching the sunlight and directing it up to your eye so you see sunlight along the swirl mark, not the paint colour. This is why these blemishes are particularly visible in bright light.
Where Do Swirls Come From?
Swirl marks can be inflicted to paintwork by a variety of means and ultimately the bad news is that it’s nearly impossible to avoid inflicting swirl marks altogether to paintwork. However, severe swirl marks can be avoided.
The most common ways of creating swirls are:
Poor wash technique - washing using a sponge traps grit between the surface of the sponge and the paint, dragging sharp grit across the paint and scratching it. Automated car washes do this on a grand scale by essentially battering grit into the paintwork and should be avoided at all costs.
Using the wrong buffing towels - using the cheapest cotton cloths will inflict swirls to the paint, as the material is hard and unforgiving, without the need for grit particles.
However, all is not lost when swirl marks appear, it is possible to either mask them by hand or remove them completely by machine polishing.
Filling Swirl Marks - Working By Hand
One method of getting rid of swirl marks is to basically fill up the mark with filler so that there's no longer a hole and sharp edges to catch the light.
Below is a diagram showing a swirl mark that has been filled.
This can be achieved by using products such as paint cleansers, polishes, glazes and sealants.
As the filler wears off over time the swirl marks starts to come back which will then require filling again in order to hide it and this process goes on and on.
Removing Swirls - Working By Machine
This is a more long-term solution for dealing with swirl marks and involves removing a thin layer of the clear coat where the swirl exists down to a flat layer where there are no swirls.
In order to remove the clear coat as shown in the diagram we require a cutting polish. A cutting polish is a liquid, which has tiny sharp particles in it, that when worked into the paint scratches the surface away.
The liquid acts as a lubricant to prevent scouring and the polishes are made in a way that the paint receives an even amount of these little sharp particles, known as abrasives, so that the paint layer remains flat and you don't just inflict many more little swirls.
Many modern polishes such as Meguiars, Poorboys and Menzerna, have diminishing abrasives which means that the sharp particles start large and get smaller as they are worked so they cut less and less. Thus they start by removing larger quantities of clear coat aggressively and finish by removing a fine amount to smooth the surface and leave it flat with the swirl removed as shown. After flattening the paintwork, a finishing polish must then be used to bring the shine back.
Disclaimer: This is my guide although the pictures aren't mind and I haven't clue who the hell made them so don't ask. If they are genuinely yours and can provide proof I will happily add your name by them
As with the other guides....any questions, comments, queries, anything else just drop me a PM.