I have a bunch of tool boxes used by masons, which have some concrete
stuck on them.

I want to remove that stuff quickly and efficiently and it is a lot of
items (four huge Knaack field stations, Knaack gangboxes and many
concrete saws).

What is the best and easiest way/chemical etc thanks

I tried a power washer, it seems to work on some stains and,
miraculously, not on others.

i