I was agonizing over how long I should let the K36 urethane primer cure before I started wet-sanding with 400 grit. I wanted to wait two weeks, even though the product is designed to be sanded the next day. I waited one week and was tempted to get started, but then something came up that distracted me for 2 more weeks, so it ended up not being a problem after all… It cured for 3+ weeks before I was able to get started. Blocking with the 400 wet was very rewarding… it’s a step I had been envisioning for a long time. It’s the LAST step before the body gets color on it! Still need to take care of some nooks and crannys, plus the rockers then it’ll be ready for three coats of PPG Concept, Ermine White. I’m very happy with how the bodywork is turning out. Very flat and smooth! The countless hours of work look like they’ll be paying off. Now, if I can manage to apply the color without screwing it up!