Yep, Perry is right, if the clear and colour are 2 very different products like one is epoxy and the other enamel. you need to make sure the base is fully cured, not just dry, before you apply the clear or it continues to off gas under it. Big difference between dry and cured. It is best to use a colour and a clear that are the same type if you want to do all the coats in a short time, but reading the cans and following what they say is always the best bet. A lot of paints have a recoat window of <20 mins or >7 days , <4 hrs or >14 days etc and that is for the time it takes to completely off gas and fully harden. If you want to get it done quick Duplicolor auto lacquers are really fast cure and can have a good 2K Clear applied over them in like 2 hours I believe for a really good finishe that is fuel safe etc. Just make sure if you use a 2K clear that you wear a respirator, not a dust mask and cover your eyes and all exposed skin.