Discovered while taking those pics of the Thermite and the Manifold, with the Cryo, that I might need to think about cleaning my working knives from time to time, more thoroughly than wiping down the blades, and blasting out the pivot areas…
My Cryo, and the Manifold, are quite grimey inside the frame rails. Looks like a combo of mud/dirt, grease and pocket lint, and dust. The Cryo is the worst of the two, not surprising, its had more carry time and use.
Had a look and all of my open back knives have some degree of dust film in them, but not this bad.
Alaskan, Adventurer, Engineer. 
Dirt, dust, grime… the evidence of work.