The clear coat paint needs to be used within a few hours or else it will harden. Always use both acrylic hardener and acrylic reducer. The higher the level of hardener, the faster your paint will dry. If you are looking to have a quicker-drying clear coat, add additional hardener.

What happens if you don't put enough hardener in clear coat?

So if there is not enough 'hardener' not all the paint molecules will be reacted with.. Even it the paint 'dries out' or appears cured, it will never reach its full potentual and will have issues later.

Do you need to add hardener to base coat?

You don't have to use hardener in your base, but its better for adhesion purposes. The clear will bond to the base a lot better. Most company's say to use 1oz per sprayable quart of the same hardener that you use in your clear.