What is the difference in makeup of Stonehenge and Stonehenge oil? I am currently applying gesso on Stonehenge before oil/wax/drypignment.

Stonehenge Oil is manufactured with a special proprietary formulation that prevents oil paint from bleeding through the paper as well as cotton fiber degradation over time. Oil painters can work directly on Stonehenge Oil without any preparation or gesso.

Stonehenge Oil features a surface texture that is similar to canvas unlike Stonehenge which has a slight vellum texture.