I'm building a cedar fence and I want it to turn gray, but we also want it to be sealed so it will last longer. If I seal the cedar, will it age to the gray color? If not, how can we get a gray cedar fence that will last a reasonable amount of time? This is in Southern California.
If you want the grey natural look anyway, I would not bother sealing it. Here in Southern California a cedar fence should last a very long time. The things that seem most likely to damage it (posts rotting out from sprinklers, insect damage) are not going to be helped by sealing, and you will have to redo the sealing frequently to keep it looking nice.
The best way to get the color you want and to keep it that color is to stain it and then seal it.