Thanks DGSketcher for showing the link to the reference guide page.
As shown in the guide page, the Surface based schedule can only list a handful of the predetermined properties (surface name, color sample, RGB color code, exposed area, etc.) of the surface materials.
If a material is supposed to have a thickness then we can use the Building Material properties to put material description and specs, but when it comes to the materials with negligible thickness such as paint, coating and wallpaper, there is no proper place to put the material info and that's the problem.
GS should really think of this inefficiency and come up with a better way to handle the custom properties of these surface applied thin materials.
Personally, I think instead of Surface we should start calling it simply Material and make it available as a place to store all the material info, and the Building Material should be simply a building block made of a base material with an option to have a different material on the surface.
Kei Mito
Architect | Graphisoft Certified BIM Manager
ArchiCAD 27 JPN USA & INT | Windows 10