yellow2000S/R
05-16-2008, 05:07 PM
At school, (WyoTech) we finished body work with 220 grit. Then you put 3 to 4 layers of a high build primer on. Wait till cured per instructions. Then wet-sand with 400 until you get the major highs down, then go to 500 till you get the shiny dots gone, and then go over it easy with 600 just to get it that much more smooth.
When it comes time for paint, take your time. You need to have proper distance, fan pattern, and speed. If you go to fast, the same with to far away, you can create a dry spray which will result in coarse paint. If you go to slow, or are to close, you could create runs/sags and also if it is a metallic, completely change the color because the flakes will tumble as they sag and not lay flat like they should. Proper distance AND spray pattern is 6" to 8".
On the guns at school, Devilbiss and Sata, a wall pressure of 48 lbs was adequate for compensating the pressure drop in the 25' hoses and in the gun to get approximately the correct spray cap pressure. You should have the fluid (paint) needle backed off. To adjust it, pull the trigger back and screw it in until you can feel the trigger getting pushed back forward, then back off it slightly and then use the thumb nut and snug it up so it doesn't move.
TAKE YOUR TIME - Have at least a charcoal respirator on for the painting stage, preferably a fresh air mask (expensive for those that are only going to do this once).
Start on one side over the vehicle. At school, we started on the drivers pillars and worked up them to the rain guards/rails and then across the roof almost as far as we could reach. Then you walk around to the other side and catch that wet edge and keep spraying front to back across the roof to that rain guard and down the pillars. Then you can choose how to do the sides/front/rear. Usually we did the passenger side in long sweeps instead of panel by panel. Then you work across the hood, again like the roof, from the passenger side to the driver side, sweeping up and down it from the bumper to windshield. Then do the bumper. Then you do the driver side and back up over the trunk as you choose. By this time, you should be about 12-17 minutes into the paint-job which is time for another coat because it already flashed (usual is 15 minutes). Have somebody assisting you pre mixing the paint and getting ready to pour it into your cup on the gun.
Keep that process going until you have 2+ coats of paint on BEING CAREFUL that you do not bump the paint with anything. WATCH THE AIR HOSE and make sure it is clean prior to painting. Let it flash for an additional 5-10 minutes after you finish the last coat, DO NOT spray the "extra" paint on. If you don't get the same amount of coats / coverage on the entire car, it will most likely be noticeable, especially depending on your primer and paint colors.
We NEVER wet-sanded the paint. I don't remember learning about it. The only reason you MIGHT need to wet-sand the paint is if you get a run / sag. Then you have to let it sit for an hour or so so it cures and then you can wet-sand it without tearing the paint off b/c of it being so soft. YOU NEVER WETSAND THE FINAL COAT OF PAINT. You should have, at minimum, 1 coat of paint over the wet-sanded area. DO NOT OVER SAND, the worst thing you could do is sand to far and go down to the primer.
Then comes time for spraying the clearcoat.
COVER YOU SKIN, NECK, HAIR. Clearcoat is sticky and irritates the hell out of you when it lays on your hair. It is recommended to have a Fresh Air Respirator for this. Charcoal masks do not protect enough but is "fine" if you are only going to do it once.
AGAIN, take your time. Do the same process as above for the first 2-3 coats (depending on how much you got). Then for the final coat, add A LITTLE more reducer than the mixing ratio calls for, this will allow it to flow a little better and fill in some of the orange peel you may have created from improper spraying techniques which in turn, creates less sanding in the end. Once the final coat is on, let the car sit. If you have access to baking it, do so. Then let the car cool and sit at least 12 hours so the clear isn't soft before you wet-sand the clear and then compound/glaze it. If you do not have access to baking it, let the car sit for 3 days till it is cured. Make sure it is in a dust / dirt free area with limited to no traffic and no wind or bugs.
Once cured, you wet-sand/compound/glaze the clear if you want show quality finish (there is less work if you know how to spray your materials right).
Option A: Wet sand
You should start with no lower than 1,500 grit. DO NOT USE 1,000 grit unless it is on the immediate area of a run or sag. NEVER GO LOWER THAN 1000 GRIT. Put a Tbsp of Dawn dish liquid soap into a bucket and fill it with at least a gallon of water. You want to sand in 1 direction, then switch 30* to the other direction. Once everything is sanded with the 1,500 grit, allow the car to air dry and check over the work for any shiny spots. The entire car should have a dull appearance, almost a white to it. If you have shiny spots, you didn't sand enough in that area. DO NOT WORK ONLY THAT AREA FOR SANDING THE CLEAR. You don't want to over sand the area and create a semi-flat area and change the reflection in the clear when all is said and done and you could possibly "burn" the paint causing it to lift.
Once finished with 1,500 grit, go to 2,000 grit. You should final sand the 2,000 grit in the opposite direction you final sanded the 1,500 grit. Allow the car to dry and look for any sanding marks going the direction the 1,500 grit was going. If you see them, keep sanding with the 2,000 grit.
Once the sanding marks are gone, you can choose to either start compounding the car now, or go to 3,000 grit. If you choose 3,000 grit, do the angle you did for the 1,500 grit until all the 2,000 grit scratches are gone.
Option B: Dry-sand and light wet-sanding
If you have a hook-it type DA sander, use 1500. Once everything is sanded with the 1,500 grit, blow the car off and wipe it down and check over the work for any shiny spots. The entire car should have a dull appearance, almost a white to it. If you have shiny spots, you didn't sand enough in that area. DO NOT WORK ONLY THAT AREA FOR SANDING THE CLEAR. You don't want to over sand the area and create a semi-flat area and change the reflection in the clear when all is said and done and you could possibly "burn" the paint causing it to lift.
Then do 3000 on the DA having a spray bottle handy. It only takes a little water to do the wet-sanding.
COMPOUNDING
Use an orbital buffer if you haven't used a rotary buffer before. If you do use a rotary buffer, stay off of edges and don't stay in one spot to long. If you get the paint to hot, you could "bubble" it which will drastically reduce the life of the paint in that area. ALSO, if you use a rotary buffer, keep the side that you are buffing with to come off of edges. You do not want the buffer pad to catch on edges. It could rip the clear and paint off.
When you are done with compounding, the clear should be relatively... well... clear! LOL You should have an even reflection on the entire car, if you notice dull spots, go over them again. Then comes glazing the car. You use a finer buffer pad and this removes the scratches from the compound and its harsher pad. Then comes final glaze which is usually applied by hand and give the clear a little more luster because it removes very very fine scratches.
When it comes time for paint, take your time. You need to have proper distance, fan pattern, and speed. If you go to fast, the same with to far away, you can create a dry spray which will result in coarse paint. If you go to slow, or are to close, you could create runs/sags and also if it is a metallic, completely change the color because the flakes will tumble as they sag and not lay flat like they should. Proper distance AND spray pattern is 6" to 8".
On the guns at school, Devilbiss and Sata, a wall pressure of 48 lbs was adequate for compensating the pressure drop in the 25' hoses and in the gun to get approximately the correct spray cap pressure. You should have the fluid (paint) needle backed off. To adjust it, pull the trigger back and screw it in until you can feel the trigger getting pushed back forward, then back off it slightly and then use the thumb nut and snug it up so it doesn't move.
TAKE YOUR TIME - Have at least a charcoal respirator on for the painting stage, preferably a fresh air mask (expensive for those that are only going to do this once).
Start on one side over the vehicle. At school, we started on the drivers pillars and worked up them to the rain guards/rails and then across the roof almost as far as we could reach. Then you walk around to the other side and catch that wet edge and keep spraying front to back across the roof to that rain guard and down the pillars. Then you can choose how to do the sides/front/rear. Usually we did the passenger side in long sweeps instead of panel by panel. Then you work across the hood, again like the roof, from the passenger side to the driver side, sweeping up and down it from the bumper to windshield. Then do the bumper. Then you do the driver side and back up over the trunk as you choose. By this time, you should be about 12-17 minutes into the paint-job which is time for another coat because it already flashed (usual is 15 minutes). Have somebody assisting you pre mixing the paint and getting ready to pour it into your cup on the gun.
Keep that process going until you have 2+ coats of paint on BEING CAREFUL that you do not bump the paint with anything. WATCH THE AIR HOSE and make sure it is clean prior to painting. Let it flash for an additional 5-10 minutes after you finish the last coat, DO NOT spray the "extra" paint on. If you don't get the same amount of coats / coverage on the entire car, it will most likely be noticeable, especially depending on your primer and paint colors.
We NEVER wet-sanded the paint. I don't remember learning about it. The only reason you MIGHT need to wet-sand the paint is if you get a run / sag. Then you have to let it sit for an hour or so so it cures and then you can wet-sand it without tearing the paint off b/c of it being so soft. YOU NEVER WETSAND THE FINAL COAT OF PAINT. You should have, at minimum, 1 coat of paint over the wet-sanded area. DO NOT OVER SAND, the worst thing you could do is sand to far and go down to the primer.
Then comes time for spraying the clearcoat.
COVER YOU SKIN, NECK, HAIR. Clearcoat is sticky and irritates the hell out of you when it lays on your hair. It is recommended to have a Fresh Air Respirator for this. Charcoal masks do not protect enough but is "fine" if you are only going to do it once.
AGAIN, take your time. Do the same process as above for the first 2-3 coats (depending on how much you got). Then for the final coat, add A LITTLE more reducer than the mixing ratio calls for, this will allow it to flow a little better and fill in some of the orange peel you may have created from improper spraying techniques which in turn, creates less sanding in the end. Once the final coat is on, let the car sit. If you have access to baking it, do so. Then let the car cool and sit at least 12 hours so the clear isn't soft before you wet-sand the clear and then compound/glaze it. If you do not have access to baking it, let the car sit for 3 days till it is cured. Make sure it is in a dust / dirt free area with limited to no traffic and no wind or bugs.
Once cured, you wet-sand/compound/glaze the clear if you want show quality finish (there is less work if you know how to spray your materials right).
Option A: Wet sand
You should start with no lower than 1,500 grit. DO NOT USE 1,000 grit unless it is on the immediate area of a run or sag. NEVER GO LOWER THAN 1000 GRIT. Put a Tbsp of Dawn dish liquid soap into a bucket and fill it with at least a gallon of water. You want to sand in 1 direction, then switch 30* to the other direction. Once everything is sanded with the 1,500 grit, allow the car to air dry and check over the work for any shiny spots. The entire car should have a dull appearance, almost a white to it. If you have shiny spots, you didn't sand enough in that area. DO NOT WORK ONLY THAT AREA FOR SANDING THE CLEAR. You don't want to over sand the area and create a semi-flat area and change the reflection in the clear when all is said and done and you could possibly "burn" the paint causing it to lift.
Once finished with 1,500 grit, go to 2,000 grit. You should final sand the 2,000 grit in the opposite direction you final sanded the 1,500 grit. Allow the car to dry and look for any sanding marks going the direction the 1,500 grit was going. If you see them, keep sanding with the 2,000 grit.
Once the sanding marks are gone, you can choose to either start compounding the car now, or go to 3,000 grit. If you choose 3,000 grit, do the angle you did for the 1,500 grit until all the 2,000 grit scratches are gone.
Option B: Dry-sand and light wet-sanding
If you have a hook-it type DA sander, use 1500. Once everything is sanded with the 1,500 grit, blow the car off and wipe it down and check over the work for any shiny spots. The entire car should have a dull appearance, almost a white to it. If you have shiny spots, you didn't sand enough in that area. DO NOT WORK ONLY THAT AREA FOR SANDING THE CLEAR. You don't want to over sand the area and create a semi-flat area and change the reflection in the clear when all is said and done and you could possibly "burn" the paint causing it to lift.
Then do 3000 on the DA having a spray bottle handy. It only takes a little water to do the wet-sanding.
COMPOUNDING
Use an orbital buffer if you haven't used a rotary buffer before. If you do use a rotary buffer, stay off of edges and don't stay in one spot to long. If you get the paint to hot, you could "bubble" it which will drastically reduce the life of the paint in that area. ALSO, if you use a rotary buffer, keep the side that you are buffing with to come off of edges. You do not want the buffer pad to catch on edges. It could rip the clear and paint off.
When you are done with compounding, the clear should be relatively... well... clear! LOL You should have an even reflection on the entire car, if you notice dull spots, go over them again. Then comes glazing the car. You use a finer buffer pad and this removes the scratches from the compound and its harsher pad. Then comes final glaze which is usually applied by hand and give the clear a little more luster because it removes very very fine scratches.