Single stage paint systems were the only way to paint a car years ago, then in the 1980’s clear coat (two stage) started to be introduced. Some people argue clear coat being a three stage process but primer is always going to be used so primer and the paint is single stage and two stage incorporates the paint layer and clear coat.
Clear coat protects the painted layer underneath and offers far more UV protection than the painted layer alone, it is also tougher than paint alone, especially the German manufactured cars. It is worth keeping this in mind if you intend to restore and polish your single stage paint.
More people want to polish single stage paints due to the fact the paint is wearing unlike the clear coat protected two stage. Single stage normally oxidises and becomes dull without care and protection. I also find you have to be careful with your product choice to protect the paint.
How do I tell if I have single stage paint? A quick way of finding out is to get some polish on a cloth and rub a spot on the paint, if the cloth comes off with the body colour, you are directly polishing the paint, clear coated cars won’t yield any colour on the cloth.
Single stage paints tend to be softer than clear coated paint, this is great in one way and a pain in another. You get quicker correction of scratches and swirls when polishing, either by hand or machine but this makes the paint more of a challenge to perfect. A compound will make a big impact on aged single stage paint, it won’t have the same result on clear coated paint but will leave a nicer finish on the clear coat, than the single stage paint. This also risks burn through, if you don’t have a paint depth gauge, always start with a fine polish to try and get you the result you want, with minimal paint removal, this applies to single and two stage paints.
It is important to remember to work clean on all paint type but especially on single stage. You have a faster removal rate, this then sits in the pad and clogs the pad with old paint, this not only scores the surface finely but reduces the pads effectiveness, it is worth cleaning the pad out after every panel, this keeps the cut uniform around the car and the finish good.
When you have finished the polishing stage it’s time to protect the finish. This takes much more consideration on single stage. My approach based on experimentation is to avoid a ceramic coating on this paint type. The coating rely on a perfect bond to the surface underneath, otherwise the coatings performance is drastically reduced. Getting the surface prepared for the coating is problematic, panel wipe which is traditionally used to remove polishing oils and fillers, can oxidise the surface again and then you need to repolish, IPA alcohol can also be used to prepare the surface but runs the same risk. I recommend rewashing the car and then using a polymer type system for protection, these don’t contain some of the harsh chemicals and solvents included in the coatings. I favour a sealant applied by machine, normally two layers and then a wax over the top, then maintain the wax every 6 months and keep the car topped up with a quick detailer.
My advice when carrying out polishing on single stage is to do this via a machine polisher, the results are better and achieved faster.