There are two different, but equally effective, methods of removing auto body paint. However, consideration must be given to the panel you are working on, especially if it has already been refinished in the past. Using the incorrect method of removing auto body paint can lead to problems when it comes to painting the job again.
Process 1 - Older Vehicles
Older vehicles, especially classic cars that have already been refurbished several times before, are likely to have several different layers of paint. There is also a likelihood of older panels containing body filler. The easiest way to cope with any potential problems is to remove all of the old paint and filler completely and start again with a fresh, metal panel.
Pour approximately .25 liters of paint stripper into a metal tin for each individual panel you intend to strip. Do not use plastic containers as the paint stripper will eat through them fairly quickly.
Apply a frame of two-inch masking tape around the outer edges of the panel you are working on and paper back with several layers of old newspaper to prevent the stripper from landing on adjacent panels. Using a paint brush, apply two full coats of paint stripper. It is highly recommended that gloves and gauntlets are worn while using paint stripper as contact with the skin can result in an uncomfortable burning sensation. Allow 15 minutes between each coat.
Once the paint has lifted from the surface, use a metal scraper to peel off the old paint and body filler. Extra coats may be needed for stubborn paint or multiple layers. Once you have removed as much of the paint as possible, sponge the panel down with copious amounts of water. This kills the active ingredient in the stripper and the panel can be dried using a clean cloth once all traces of the paint stripper are removed.
Remove the masking paper and tape and use a P80 sanding disc on a random orbital sander to remove the remaining paint edges on the panel.
Process 2 - Newer Vehicles
It is rarely necessary to remove all of the paint on newer vehicles. Problems only tend to arise on panels with multiple layers and types of paint, which have a tendency to cause a chemical reaction when fresh color is applied.
Newer vehicles are most likely to be factory finished and if any work has been carried out, the chances are that new water-based products will have been used to paint them. This should mean that any subsequent topcoats will be compatible.
However, paint will still need to be removed from dented areas to allow good adhesion for body filler. Using a random orbital sander with a P80, simply work your way around the area to be repaired thoroughly until the paint is removed. Allow approximately two inches of paint removal beyond the repair so that a sufficient amount of body filler can be applied.