Although we only use the best materials: Select Cedar, Select Fir, Select Pine, marine
grade outdoor polyurethane with UV protection and water proof glues, all materials are subject to wear from the weather. Therefore, if you want your sign to last you need to give it a light
sanding and two to three more coats of polyurethane once a year or when you see the clear finish has worn away in any spots. Graying of the wood means it has lost it's protection and damage
The amount of maintenance required depends on the amount of sun and weather it receives. Modern finishes are designed to wear away rather then flake and blister.
All wood requires protection from the elements. Cedar is more resistant to decay then other woods if unprotected but if any wood is protected and that protection is maintained, it will last.
I recommend using: Deft Polyurethane Interior/Exterior Water Based - Semi-Gloss.