Voisin 10 Center Section Fabric
The Memorial Flight recently restored a Voisin 10, shown above in their workshop outside Paris. During the restoration they had to replace the original fabric covering the center section under the fuselage, shown below removed on the left, a small piece of which was donated to The Aero Conservancy.  The material is painted in a black-pigmented dope and appears to have a stamp of some sort, possibly the factory mark.