What finish do you use and how long will the sign last?
We use Sikkens Cetol log cabin finish on our Eastern Cedar slab signs. Sikkens is fairly expensive as finishes go, but we've tried a number of finishes over the years and have found Sikkens to look best and last the longest outdoors. Since our purpose is to provide a quality and long lasting outdoor product, we don't skimp on finish quality.
Our Eastern Cedar signs will give you years of pleasure, with a little maintenance they can last a lifetime. The are lots of factors that will effect exactly how long your sign will look new and last and when maintenance may be required. The red heart of eastern cedar naturally repels bugs and is highly rot resistant even when unprotected by finish, the white sapwood, while not as resistant as the heartwood, will last a long time. An eastern cedar sign without finish will slowly turn a silver grey and will stand up to the weather that way for years. Exposure to the elements including rain, freezing/thawing and UV from the sun all affect any wood or finish. A south facing sign on a fence post will get the most exposure to the suns UV rays and weather, while a sign under a porch is protected from most of the elements. Even in the worst case of extreme exposure to the weather and sun, our sikkens coated signs should last several years before they need maintenance. I still have the first sign I did using sikkens and it looks nearly as good as the day I put it there more than five years ago.
When your sign does need maintenance, wash it with a wet cloth and let it dry thorougly, then using a rag or foam brush, wipe on Sikkens Cetol Natural finish. You don't need to buy a full gallon at $90 or more, most dealers carry a small sample can with a built in brush for a few dollars and it's more than enough to refinish a sign.
You can find your local Sikkens dealer on the Sikkens website. If you can't tell already, we really like the the Sikkens product and if you're building a new log home or want to finish a new deck, outdoor furniture, or other outside wood project, I recommend you looking into it.