I have seen gaffer tape (or any other brand name) used as rim tape. Coroplast is another brand that probably has provided polyester, achrylic and various technical tapes for two or three generations back. On a 1969 Raleigh I have the original rim tape was a non stretch unbleached cotton tape (binding tape the same as for clothes making) and the ends was sort of joined together with metal hooks, no glue used. These were woven in a fish bone pattern. I think you still can get the Velox version of this with sticky backside. I don't know about the Varia brand, and you found what you searched for, but if you are looking for something similar, any woven nylon adesive tape could be an alternative?