Last time I painted a car it was 20 years ago and with Lacquer...boy that was a lot easier! So I sprayed my 79 with 5-Star High Build 2k DTM Primer Filler/Sealer (item 5425) along with their activator (item 5426). It was about 85 degrees in the garage as I was spraying it. I sprayed the fender the night before and everything came out good, but this second job did not go so well. The surface was extremely bumpy, as seen in the picture below. I then sanded this down a little bit (about 30 strokes) with 180, and this is what it starts to look like. I keep going for another 100 strokes with 180, and this is the result - finally getting to a smooth surface. So, looking for some advice as to what the cause is and how to prevent this from happening again. I tried to do a 50 % overlap in spraying, and I tried to go slow, but it seems like it is just drying too quick, not allowing the primer to flow out. I am spraying with a 1.7 tip. Is there a thinner I can use that might help this out? Am I simply going to fast or not doing enough overlap? Any advise on what I am doing wrong and how to correct is greatly appreciated. Thanks, Rich.