Sealing Wooden Signs

How to seal over natural wood and painted lettering on an outdoor sign. September 26, 2013

I completed a couple of wood signs using western red cedar. The lettering and artwork are all inset-cut (not raised lettering) and we painted the lettering/artwork with an oil based enamel paint that took a long time to dry but I expect durability from this coating.

I am wrestling with what to seal the rest of the signs to prevent the cedar from greying out over time. I've used Penofin penetrating rose wood oil before but not with this enamel. I am being cautioned that regardless of what I put over the signs some oils for raw wood may loosen or even attack other paints previously applied. Has anyone tried a coating like this that stays pretty clear (doesn't darken the cedar too much) and would leave the enamel alone but protect against weather too?

Forum Responses
(Finishing Forum)
From contributor J:
Akzo-Nobel makes outstanding coatings for exterior signage. They have a waterclear called Chromatic that's really good for a non-catalyzed finish. Itís thin with High-Flash naphtha (solvent 150) or you'll be spraying cobwebs. This was sprayed over One-Shot sign painters enamel on wood, metal, and plastic and never had a bad reaction. Itís our go-to finish over enamels and acrylics.

From contributor A:
I regularly hand router signs for clients who want a rustic durable outdoor sign that will stand up to our harsh ozone hole conditions. I have found that using PPG Autothane wet on wet, (as per car top-coat application) works well. It does not darken the timber and I have used it over Danish oil, acrylic, and oil based paints without any problems.