What is the recommended way to clean old 4x5 stainless hangers. Mine have a black tinge to them and my fingers get black now when I handle them.

Scrub them down fully inside and out with Scotch-Brite under warm water.

After each use... rinse, wipe and air dry overnight.

Typically what you described happens when left in tanks for extended lengths of time... as in the olden photo studio days.

It's probably caused from the buildup of silver when replenishment rather than changing chemicals was in vogue.

That "black tinge" is probably a fine powder of silver bromide, chloride, floride, and/or iodide that can be removed as suggested by George B. Almost any non abrasive material, including Scotch-Brite, can be used under warm water or in a mild dish washing detergent. If a detergent is used thorough rinsing is required to avoid contamination of the photo chemistry.

C. Henry