Today was a productive day in the Hatcher Knife Shop.
First, I used Q-tips to apply regular yellow mustard to the tang and ring area of the wharncliffe. I wasn't sure if the vinegar/lemon solution would discolor the coyote G10, so I didn't take any chances.
The mustard worked much more quickly than I had anticipated. Within 10 or so minutes, there was an obvious patina forming. The consistency of the mustard, while useful for staying in place better than a liquid, created a mottled look. My solution was to wipe it off and reapply it a few times to obtain a more uniform finish to match the rest of the knife.
From Knife Making