Saw a couple of posts asking for sources of guaranteed acid-free activated carbon.
Here is one way to actually test for that: 3D print a small carbon holding cube, have a small fan blow on it, enclose in a tupperware box with a few steel sbolts & drops of water. If any rust appears within 24 hours keep that carbon the HELL AWAY from your printer !
More details, with 3D CAD and STEP files, here: [DIY] Acid-Free Test for Activated Carbon in 3D Printer
