when sanding how far should I sand? To the metal or until the color doesnt shine?

 

Until the color doesn't shine. If the paint is still in tack and not flaking.

 

Depends on the situation. Painting over a modern factory or refinish system, that is in sound shape, sanding till shine is gone and painting over it should most likely be fine. An older 1k enamel or lacquer finish, several paint jobs are already on the vehicle you are taking your chances. Those old finishes or primers would be the weakest link if modern 2k material is used. Sealing with a 2k sealer would be minimum, and starting fresh by stripping too bare metal would probably be the safest to be assured of a long lasting and durable finish, and also to know there are no poor repairs underneath. Its possible for a lot of nastys to be hiding under paint, especially one thats been around for 30 years. The musclecars and old trucks were at one time just another vehicle, quite a few kids back when I went to highschool drove 70's and older vehicles, and they were actually considered beaters that were handed down to kids, and could be boughten fairly cheap. Even today, you would be surprised at how many people have a classic vehicle and are looking for a cheap way out when it comes time for body and paint(Just look at all the tractor paint, rustoleum and lacquer threads around the internet), even though the value of many of these not too long ago beaters is a bit more today. Just remember, paint is only as good as whats underneath it. If its a fairly new vehicle or it has been painted or repaired with modern materials and your sure of the repairs were done well, paint is adhering well, and the finish on it is not softened when soaked with solvent, should be fairly safe with a sand and shoot job. If not, all bets are off, starting fresh, seeing the true shape its in, and using modern 2k materials from the ground up would be the safest if longevity is the goal..

 

Would you spray the sealer primer over the complete vehicle to cover all the old painted surface. I have a 78 F-100 and 76 Chevy 3/4 ton and both need painted. I am just learning about paint and body work so I dont know muck in that area.

 

I'm guessing here, but with it being that old the chances of having clean paint on it are not high and there will be a lot of featheredging scratches out.

So prime it all over.

 

Seal it all with a 2k sealer or primer. Not only will help prevent an incompatabily between the old 1k stuff and the new, Its often best to have all one color for coverage of base. A good paint supplier should help you with what shade or color of primer or sealer you want to try to go with for best coverage based on the color you choose. Some colors and quite often the lower lines of base can be downright transparent-poor hiders. If you have different color spots all over, If color happens to be one of the poor covers, your often blowing a lot of paint over it to get the primer spots and old color all the same. If your using the same color as whats on the car, might not be quite as big a deal to prime all one color, but still would choose a close shade, and being your paint is that old, probably full of defects to fix like wart mentioned, and outdated paint system, you most likely want to prime it all.

 

Before you sand clean the surface with a silcon remover. Its cheap insurance availble at most auto paint supply houses. If you dont the silicon (from wax jobs and show shine) will not come off with sanding it will just be driven down into the sanding scratches and will show up in your final finish as fisheyes.

 

Yes with the 2 rag method.

Do it again before you paint it and then tack it off.