Saul,
I would only use a solvent to remove moulding oils impregnated during the mould process (not necessary on a car already painted like the Bachmann cars). Never use automotive thinners as a plastic solvent. To remove logos/insignias on a car that is to be overpainted, then I use an extremely fine black sanding paper used in the automotive respray industry. We call it ‘Wet’n’dry’. It is used in conjunction with water which washes away the residue grit from the sanding to minimise scratching. For fine detail sanding like logos, I would use a grade 800 or 1200 paper to minimise scratching. When repainting Bachmann coaches, I always lightly sand the painted finish and existing roadname (400 grade grit paper), to enable overcoats to key with the existing painted surface. It only requires a light ‘scuffing’. Bachmann painted surfaces can be very tricky to overcoat, particularly black and red/maroon painted surfaces.
I purchase my primer undercoats from auto accessory stores and never purchase the economy brandnames. Hobby store undercoats tend to be expensive for the purchased quantities, due small aerosol can sizing (around 50ml to 100ml). I prefer the larger 'jumbo' cans around 400ml from auto accessory stores, as these are more economical. Ensure the primer purchased is compatible with plastics, as very few actually are and the plastic surface crazes. Also it is a false economy to buy hobby store spray paints, as to paint a single coach would require at least three or four hobby-sized cans. I buy either hardware store or automotive accessory store paints, ensuring to never buy the cheap economy brands.
If you have never previously embarked on painting larger objects like coach bodies, then I suggest practice spraying on scraps, prior to painting the car body.
