After two bucket method has been done you should be left with largely clean bodywork. Inevitably however there are going to be bits of resilient dirt. Commonly these include tar from the road and bugs that have sealed themselves to your car that are too ingrained to be removed with a mitt.
The easiest and safest way to remove the majority of these imperfections is to apply a chemical solvent such as the popular Tardis. These are very strong chemicals that will soften virtually all tar and bug residue allowing it to be wiped off with a microfibre towel.
Once you have your chosen product (in my case Tardis) apply it to your car as instructed on the bottle. Usually I will apply it by spraying the entire lower section of the car (from the side bump strips down) all round the car working around it side at a time.
I apply the solvent, leave until it turns cloudy and the tar is running, then wipe it down with a microfibre. At this point I will rinse the side with the power washer to ensure the solvent I not left on the paint for long durations.
It is recommended that this process shouldn’t be performed too frequently as the paint would end up being damaged by prolonged exposure to the strong solvents. I tend to do this about quarterly, however if you wanted to do it more frequently you could dilute the concentration or reduce the dwell time to reduce the impact.
While this will eliminate a lot of the stubborn marks some elements will remain. These will require a slightly more advanced technique to remove known as claying. This is covered in depth in the advanced tutorials section.
After I have chemically removed tar and bug splatter I will move on to a last stage protection to try and lock the great finish of the paint down for as long as possible. See the LSP tutorial for more details.