Runes are SYMBOLS. Have you ever seen a blank symbol? No? Neither has anyone else.
Runes are NOT the medium on which they are carved or drawn onto. They are the SYMBOL that is carved or drawn onto that medium. Symbols carry power, emptiness carries nothing.
Around this room I see a blank notebook, it that a “blank rune”? Or how about the blank side of a garbage can, is that a “blank rune”? Or the blank wall under my window, is that a “blank rune”? No, no and no.
Some even attribute this so called “blank rune” to mean unknown mysteries or fate, which clearly shows they have no idea what they are talking about as this is the domain of the Rune Perthro.
If anyone ever tries to do a reading for you using a “blank rune” in the set, I suggest you walk away, quickly.
There is no “Blank Rune”.