Exterior Signboard Material

Modern plastic materials are the way to go for outdoor signs. August 6, 2008

I've got 3 storefront signs to make, each with individually cut out letters to be applied over a backer board (in one case it's a 10' surfboard). I plan on using MDO for the backer but I'm not sure if the resin coating on the MDO will protect the edges of the letters from the elements. Any thoughts about material choices? I was also thinking of spraying or dipping the letters in lacquer for a weather resistant finish.

Forum Responses
(Architectural Woodworking Forum)
From contributor A:
We used to make them the way you are thinking but no matter how we finished them the edges would blow after time. Recently I've seen a type of foam being used. It's the type commonly seen in PVC window boards and the sign writers just spray the letters with car paint. Job done!

From contributor B:
Styrene is the way to go. It is lightweight, machine-able, weatherproof and comes in many colors.

From contributor C:
My neighbor is a signmaker and as the previous poster said, no wood products anymore. They have different types of sign foam which can be machined and painted and last longer than we'll be around. I would suggest at least looking into it as you may save yourself a lot of headaches.

From contributor D:
I never use wood for outdoor signs anymore. I use sign foam, and lately, mainly sheet PVC. It mills nicely, takes paint, and withstands environmental forces. It is stronger than sign foam if there is an issue with vandalism.

From the original questioner:
I ordered samples of Extira and will most likely use that for the project.