I cleaned some rusty old parts (old milling cutters) last night in a water & citric acid solution and I left them too long and they all had a black layer over them. IIRC it's magnetite and it needs to be scrubbed off quickly before the parts dry or it sticks pretty good. So I've been scrubbing them and cleaning them with soap and a brush for a while now.
But now I am wondering if there is a better way to clean the parts when this happens, or even better, some way to avoid it, aside from not forgetting the parts and leaving them too long...
And does anyone know why this forms? And how to prevent it? I have some vauge memory of being told it happens because I use tap water. Tap water in Finland is pretty damn good, but it's not free from minerals and stuff like it was distilled or deionized water. But I am not sure what mechanism there is that causes trace minerals in the water to react with the iron in steel parts.
Or does it just come with the territory?
But now I am wondering if there is a better way to clean the parts when this happens, or even better, some way to avoid it, aside from not forgetting the parts and leaving them too long...
And does anyone know why this forms? And how to prevent it? I have some vauge memory of being told it happens because I use tap water. Tap water in Finland is pretty damn good, but it's not free from minerals and stuff like it was distilled or deionized water. But I am not sure what mechanism there is that causes trace minerals in the water to react with the iron in steel parts.
Or does it just come with the territory?
