Auto paint, repainting clearcoat?

I am going to repaint my clearcoat on the vehicle I just painted. the undercoats were great, but the clearcoat did not come out right.





The clearcoat came out in droplets, I am told this may be an effect of drying too fast, or improper technique.





I am going to sand the clearcoat,, questions:





1 does it have to be, or ';should'; it be wetsanded, or is drysanding ok?





2 what grit sandpaper should be used?





3 how much sanding needs to be done? in other words, do I have to sand smooth ';to touch';, or to where I can not see the ';droplets';?





4 Any clearcoat technique tips, using hvlp?





clearcoat is ppg shopsline jc661





thanks.Auto paint, repainting clearcoat?
1. Dry will work, but I prefer a wetsand.


2 That will depend on the surface condition.


3. Yes.


4. Find what caused the ';droplets'; and don't do it again!





I'm not sure what you mean by the droplets, but I think you are saying the clear didn't atomize fully, or maybe you have severe ';orange peeling';. If using HVLP you may need to add some reducer to the clear as well as the activator. Be sure to use a motion that will give a ';full wet coverage';, not a dry spray, then allow to flash off for 15 minutes or longer.





In sanding what is already done, if you go through to the base coat, you will have to respray it (base color). Try to even out the clear with a 400 to 600 grit wet or dry. Any imperfections in a previous coat will show in a future coat. You can't ';hide it with paint'; that doesn't work! You need to get it down to a smooth surface. Spray at least 3 coat of clear and you will be able to color sand later and buff it if you want to.Auto paint, repainting clearcoat?
That was a pretty excellent answer.





One more thing to remember is to be very careful when you are sanding on the bodylines. It is easier than you think to burn right through the clear andthe base coat. If that happens you will be re-spraying the base and you don't want to do that.





I don't know how rough your clear was. I'd recommend that you re-paint in a good environment. I know it is cooler out now and you might be tempted to used a reddy heater or something to heat up your area. (I am assuming that you are not in a professional booth on this job) Don't! There is something about the exhaust of the heater that really fish-eyes the finish. Use electric heat and it is best ot do it in a real, heated booth.


But the bottome line to that was that you need to sand your old finish as smooth as you can or it will show up again as you add new coats. Depending how rough your surface was you might want to drysand first. But when I start getting to the end I like to go to wet sanding with a sponge/block and making sure the panels are all slick before I move on.