All simple carbon steels will rust and stain, if not protected or fastidiously cared for. And 1050 is certainly the most simple of carbon steels. Iron, and 0.50% carbon, and 0.6% to 0.9% manganese That's it.
This stuff will develop rust spots even indoors unless you wax the blades. It's not a problem indoors, you just wax.
Used for much of anything, they stain.
[This message has been edited by rdangerer (edited 02-08-2001).]