Tannin Bleed Test Results
Tannin can be a problem...
Tannin bleed: Bin Synthetic Shellac, gesso over 2 coats (1 hr recoat); Bullseye 123, gesso over 2 coats (24 hr recoat); Daniel Smith Watercolor Ground, gesso over one thick coat that has had 24 hr dry. Bin and Bullseye have stain lock after 1st coat, 2 coats primer to be safer. DS Watercolor Ground has no stain block and tannin bleeds into the gesso, must use stain blocking primer on hardboard, cedar, redwood, etc with the DS Watercolor Ground.
I prefer to use the Bin Synthetic Shellac because of the rapid recoat. Bullseye needs the 24 hours to lock in tannin stain. Hoping that DS Watercolor Ground would be a one coat solution... but it is not.