You will hear several different stories about how to get the optimum paint finish. Some can be very costly, some have have very poor results. A Brabus splitter for a fortwo was painted River Silver after previously being Ferrari Rosso Red. This was the method I used in order to get a finish that I am happy with.
The splitter was rubbed down using some coarse sandpaper to take off the lacquer only. The painted finish below was then rubbed up with medium grade paper to blend in the effects of the coarse paper.
Using an air compressor and paint bottle, the 50% of the new paint colour was mixed with 50% of cellulose thinners.
The splitter was positioned such that none off the painted surfaces would be in contact with the ground. Due to time pressure, the painting was done outside to use the sun for drying. This is not ideal as foreign bodies can get on the painted surface. The best environment would be a warm space indoors.
Test on another object to ensure that the paint flow and distribution settings are correct on the paint bottle. Then begin painting!
Rather than strip the splitter all the way back to the base, the old colour worked perfectly well as a primer to which the new paint stuck to very well.
Be firm and positive when painting. Don't focus on complicated areas as this can cause a build up of paint and the potential for runs! The first pass may not cover all areas but don't worry.
Leave the paint to dry fully and sand it with very fine paper. Repeat the painting!
In order to cover such a colour change, I needed to repeat the painting 4 times.
This allowed complicated areas to be fully covered.
Once complete, the splitter was given one last rub down.
Lacquering is the final step...where it can all go wrong!
Again, a mix of 50% laquer to 50% thinners was put in the spray bottle. A fairly liberal coat of lacquer was sprayed over the whole splitter. Complicated areas were detailed at the end. Being more fluid than the paint, it blended into itself better with few imperfections.
The splitter was then dried in a warm room for a few days while the lacquer hardened.
Once dry, the splitter was inspected. A light rub with some T-Cut and a thorough polish managed to create a very smooth finish.