Does sodium chloride or magnesium chloride have any effect on hardwood floors? I use ice melt outside peoples houses when moving in their furniture in the winter, some people ask if it will hurt their flooring?

I do not have any scientific proof, but I think that it can't be good for the finish.

While it is probably not good for the flooring, i doubt you would "see" any problems with it.

I tried to search Google for a definite answer for you and was unable to find anything worth posting. But if you haven’t had problems in the past, I wouldn’t really worry about it. Just wipe the floors before you leave.

In my opinion, water on wood is never good. Salt will stain red oak, for sure. It goes green. I know from experience. If you are installing unfinished, the stains will come out when you sand it. Salt won't react with aluminum oxide on prefinished. Put it this way: Aluminum doesn't rust with salt. Aluminum is naturally always covered by a thin layer of aluminum oxide. Aluminum oxide is what they use on prefinished. I'm sure if you let water soak in between the boards long enough, the floors will get wrecked.