Salix Changes Paper Color Perception

[Scrivener1]

Has anyone else noticed that a page written with Rohrer & Klingner's Salix takes on an aged look? A perfectly white paper comes out looking off-white and antique after the ink has cured.

 

I suspect this is because the dusky hue of oxidized iron gall duplicates somewhat the impression of a clearer blue on off-white paper, but it's different somehow - more aged than exactly off-white. I wonder if it's also partly due to the way, as Sandy1 puts it, iron gall inks seem to reside behind the plane of the page.

 

I think it is a great effect and lends a document gravitas; but I certainly wouldn't have predicted it. I wonder if the other iron galls do the same thing.