"Things You Wouldn't Know If We Didn't Blog Intermittently."
That looks like encaustic painting, with pigment and beeswax. The colors are so vivid still.
Interesting comment. I hadn't heard of it, but looked it up and found this -"This technique [encaustic painting] was notably used in the Fayum mummy portraits from Egypt around 100-300 AD, in the Blachernitissa and other early icons, as well as in many works of 20th-century American artists, including Jasper Johns."Nice observation.