Generally, Neon colors are not very UV stable. 2 years is a decent amount of time (environment depending of course). Clear coats will not really help with UV stability either. They will help disperse the direct UV rays but ultimately you will see Neons fade sooner than other colors.
Kurt D. Beckman | Prismatic Technical Advisor
PRISMATIC POWDERS | Innovation of NIC Industries, Inc.
Series 59 NEON Colors
POWDER COATING FOR EXTERIOR APPLICATIONS (NOT FACADE)
2-COAT-SYSTEM, CLEAR TOP COAT IS REQUIRED
BASE: POLYESTER, BUT ONLY LIMITED UV- AND WEATHER-RESISTANT