Ok, so you're primed up and you've left the car in the sun hopefully for a good 5 or so days to make it shrink up. You are now at a crossroad. You need to think how perfect you want the car to come out.

Option 1) You can sand down the primer with a D.A. (dual action) air sander. If you go this route you would ideally want one that is very tight and does not have any slop in the bearing so that you cut a nice level cut. You can also use a high quality orbital air sander such as those made by Hutchins (approx $275). If this is to be a nice paint job without looking for perfection you can use 400 grit paper on the sander and follow behind that with a scuff pad. You can use either a red or a gray scuff pad but if you use red DO NOT LET THE SIDE WITH THE WHITE LETTERING SAND THE SURFACE SINCE IT IS MORE LIKE A 220 GRIT THAN THE OTHER SIDE OF THE PAD. The scuff pad will remove the swirling scratches left for the D.A. Also, you can use the scuff pad to get into tight areas around windows and any trim that you have elected to leave in place. REMEMBER IF YOU DON'T GET A SCUFF ON IT THE PAINT AIN'T GONNA STICK TO IT. You want to keep your hand flat and let the palm of your hand do the work pushing the scuff pad. You'll notice when you've removed the D.A. marks since the scuff pad's marks will be visible. At this point you're prepped and ready to start cleaning it up for the spraying.

Option 2) If you want a little nicer job go this route. Now that you've sanded it with the D.A. you can go ahead and reprime with 2 more coats of filler primer. Naturally you'll want it to bake in the sun again. Once it is fully cured and shrunk you can wet-sand it. With the wet-sanding you should start with 400 grit and progress on to 600, 800, and finish up with 1000 grit. You can make your own decision on whether or not you are content with stopping at a certain grit without going for the gold all the way up to 1000. I have done it multiple ways and stopped at any of those grits with out a problem. I will tell you that when you finish sand with 1000 the primer has a sheen on it that looks like it could be buffed to a full gloss. That is beneficial because it will take less matierial to cover the scratches. If you finish it with 1000 you could get by without sealing the finish if you chose to do that.

Option 3) OBSESSION!!!!! Yeah this is the level that a concourse car or a high end custom will follow. Wet-sand it the first time using the same grits as above and go all the way to 1000. Then reprime and let it shrink up. And of course wet-sand all over again. But this time go for broke and wet-sand that sucker all the way. You'll start off with 800 then jump to 1000, 1500 and for the best finish possible cap it off with 2000. WARNING THIS IS AN INSANE AMOUNT OF WET-SANDING AND YOU ARMS WILL BE EXTREMELY SORE. Wet-sanding a car to this extent will probably take you at least 60 hours of solid sanding time to get through both rounds of primer.

Now I'll throw out some other possibilities for you. You can block the first round of primer with 180 on a file board if you have concerns about waviness and distortion. This is more advisable with a dark color due to their greater reflectivity. You can reprime as many times as necessary but remember, do not due any more than necessary because excessive material build makes the finish more prone to checking, chipping and crows footing. You'll want to use a foam block to wrap your wet-sanding paper around. DO NOT EVER WRAP SANDPAPER AROUND YOUR HAND AND GO TO TOWN!!!! This will leave sanding distortions about the size of your finger tips since they will be the only things keeping the grit of the paper pressed against the surface. If you have a very flat vehicle with few or no rounded contours you may choose to use a rigid block. DON'T BE CHEAP, BUY GOOD SANDPAPER AT LEAST FOR THE FINAL SANDING. 3M and Meguiars Unigrit are the best options. Finish up around any hard to access areas with a wet gray scuff pad. IT IS EXTREMELY IMPORTANT THAT YOU LET ANY SANDPAPER TO BE USED FOR WETSANDING SOAK FOR A BARE MINIMUM OF AN HOUR IN YOUR SANDING WATER AND CHANGE YOUR WATER OFTENLY TO PREVENT GETTING TRASH ON YOUR SANDPAPER THAT COULD GOUGE YOUR FINISH.

This will get you to the end of the surface prep and bring you to the paint prep. You'll want to thoroughly blow out any gaps and seams with compressed air to get any of you sanding slag and dust off the car. Be sure to wipe out all seams and jambs to remove all the mess from the sanding operations. CLEANLINESS IS NEXT TO GODLINESS. Once you've got everything cleaned up you're ready to blow it back off. Now you can do any remasking and then blow the car off again. Try to get your blowgun's nozzle tight to any gaps or seams to force out debris. BE CAREFUL TO AVOID DIGGING INTO THE SURFACE WITH THE BLOW GUN.

Now it's time to sanitize. you should select a quality prep solvent. There are several choices but they all fall into 2 main categories.

1)Water based. These are good as you're final wipe down. They will get any loose dirt and dust out off your sanding scratches and they leave no residue.

2)Solvent based. These are better to use for cleaning as you progress through the prep process and as a second to last wipe since they are better suited to removing contaminants from the surface of your work.

If you're only going to use one of the two I would recommend going for the solvent based. You'll be fine just using this, as I have plenty of times. The only thing to be sure of is that you go one panel at a time. Wipe it on with a wet towel and wipe it off with a separate dry one to prevent any left over residue. You want to use towels intended for this purpose such as those made by Tork. These are lint and static free which is critical to the finished product.

After that you're ready for the final prep operation. This is called tacking. You must select a high quality tack cloth and I would try a sample before deciding that you are going to use it on your paint job. You want one that is tacky enough, but not excessively tacky. You should feel some residue on your hands or gloves but it shouldn't leave a snail trail behind. When you're ready to tack it open the cloth and completely unfold it. Now Ball it up slightly so that it is a manageable size. I know this sounds stupid but it helps keep the static charge under control. Be sure that you don't push too hard while tacking, you don't want to leave any residue behind or you will have to use prep solve to clean it off and then have to retack.