The top coat spray is best used to protect water-slide decals on your rocket. It can also be used to add a "gloss" to the paint.
Allow the paint to be clear-coated to fully cure before applying TS13. This will prevent the clear coat from cracking due to different cure rates from the paint underneath. For best results allow up to one week.
Make sure to test clear coating over decals before applying to a finished project. Applying clear coat can harm certain decals.