What is the best way to clean old equippment.

[hillegom]

I had some muriatic acid once, used it to remove concrete from a rock wall. It dissolves
the concrete binding agent and leaves you with sand.
But I can't remember. If you want to dilute it, do you add water, or do you add the acid to the water. I remember there is a big saftey issure here, if you do it incorrectly,