TR2/3/3A Scuff sanding a car to prep for a paint respray?

[karls59tr]

If a car is going to be respayed a different colour and the bodywork is otherwise OK what grade sandpaper should be used on the body to give the paint something to bite into but not leave scratches?
ie. 220...320...Scotchbrite pad or??

 

[bobhustead]

Gonna depend on the new paint. My single stage acrylic poly asked for 400 wet. Another paint may be different. The poop sheet you get from the paint supplier will tell you.
Bob

 

[trrdster2000]

Karl, I don't want to be a party pooper but if you don't put some type of sealer on a car that has been exposed to all kinds of environmental junk, there is bound to some reactions in places the rub down won't get.

Just a small step in a really good paint job.

Wayne

 

[sqbsprite]

What Wayne says is true. You should first clean it with a prep solvent that will remove wax and grease before you ever touch it with sandpaper. Otherwise the sand paper will just rub it into the surface of the old paint. If the paint is really sound, I would use 360-400 wet and then apply a sealer. I would prefer one that can be sanded because it provides one more opportunity to remove small scratches. Then wet sand with 400 and paint after cleaning and tacking. Depending on the paint you are using, there will be recommended sealers.

 

[Marvin Gruber]

As others have mentioned, I would 220 grit sand, prime seal or even epoxy primer, sand then with 400

Marv

 

[karls59tr]

Thanks for the info guys.

 

[PatGalvin]

Karl

A few thoughts. First step is to wash with a nice concentrated solution of Dawn dishwashing detergent and blow dry with a leaf blower or leave it out to dry, if warm enough. Then, a wipe down with Wax and Grease Remover (which you can buy a gallon at any auto paint shop). If existing paint is sound, you should be able to scuff with 400 grit and then wash and wipe down again. At 400 grit, wet sanding is probably the only way to go. Dry sanding loads up very quick at that grit. And use really good quality sand paper. Cheap sand papers load up rapidly and leave scratches of varying grits. You could do a lot of that scuffing with a pneumatic palm sander to save some elbow grease. When super clean and dry, I would shoot with a sealer coat (unless you are sure your existing paint is compatible with new paint) and then hit it with the single stage paint or hit it with base coat and clear coat.

There really isn't any requirement to sand your sealer. In fact, best bond will be if you shoot the sealer "wet on wet" with your base coat or single stage. If your current paint isn't competent, then remove it. If your sanded current paint isn't smooth and free of defects, then fix those before you start shooting sealer. Sealer is a very light "adhesion" layer. If you have scratch problems, fill with either two-part glazing putty or fill with polyester primer (sprayable bondo) or with urethane primer (which sands the best). Don't use sealer to address scratch problems (unless they are very minor). I have seen sealer fill scratches from 320 sanding but I think most would agree that lower grits need more than a sealer to deliver a scratch free finish.

And if you are shooting metallic, then you need to finish with 600 grit, not 400 grit. A bit more work.

Hope this helps. Just my opinions and there are lots of ways to deliver a great paint job. I used every product I mentioned in this post for my TR3 resto.

pat

 

[tinman58]

Take Pat's advice. He knows what he is talking about. His TR3 is awesome!

 

[karls59tr]

Thanks Pat

 

[Jerry]

AH, don't listen to Pat, he makes me work harder on my paint jobs. I only wish I could match his paint job.

Jerry