Hand Tools Archive
..I've used several manners of commercially available iron and steel plates, but none have been close to as good as the plate that phil sent me as part of the iron testing.
I still haven't figured out how to sharpen something on the cast plate every single time freehand without any defect, but the little nits that occur would never bother anyone else and are so tiny that they have no effect on longevity.
My cycle time using a diamond hone and the cast plate is no less or more than a simple iron on a medium that I find a little easier to use (low side just over a minute to two minutes for something with issues that need to be removed).
If those plates weren't fastened in a frame, I can't imagine how much damage they could do to themselves or the box in regular packing. They're potentially missiles.
I like to flatten planes, and have enjoyed learning to flatten infills with a file to flatness similar to premium planes, but the effort involved in filing slightly hollow and then lapping and checking just isn't worth the trouble with a flat plate.
Anything with slots in it is unsuitable (those types are generally flat), most of the inexpensive japanese kanaban aren't actually flat (and they're gummy mild steel), etc.