We have had good success with the SEMS product. The key to it is proper prep work using a good cleaner on it first (such as simple green)
Second lightly scuff with scotch brite pad or a fine sandpaper. 600 grit or finer.
Third wipe down with rubbing alcohol and then apply.
As mentioned on this thread, a heat gun is a great way to build a nice solid coat. More thin coats over heavy. Also, keep in mind that this product cures in 10-15 seconds with light coats so don’t bake it with the heat gun. Use it just to keep the surface dry and warm.
There is no top coat needed. Though if you wish, SEMS has both a low luster clear or a high gloss clear if you want to put a top coat over it or for a different shine.
If you have any rough surface or issues with your spray you can also lightly scuff your job with 2000 grit. It will give you a soft perfect feel and can be polished off afterwards by hand with 3M Perfect It to get a flawless finish. This can be done with the color as well as the clear.
If done this way, we have had great success with the product and should hold up for several years and is simple to reapply down the road using the same process.