I have been told this is only one of five known to exist , and this one is the second best one in condition. I believe this was Conoco's first sign. It's not porcelain, and I've been told the process was called Sand Paint. This measures 48" x 48". It's expensive, but find another.
The item "SUPER RARE Vintage Conoco Sand Paint Sign" is in sale since Monday, June 26, 2017. This item is in the category "Collectibles\Advertising\Gas & Oil\Merchandise & Memorabilia\Signs". The seller is "56convt" and is located in Nampa, Idaho. This item can be shipped to United States.