Magnetic Card Questions

[Thomas Okken]

A Staedtler Mars Plastic or similar eraser works great for getting pencil markings off magnetic cards. Probably not so great for marker ink, but I couldn't really say, I've never had to deal with that. Just one word of warning: be sure to hold the cards firmly at both ends while erasing, else it's easy to accidentally bend the cards too far and that can render them unusable.

I've never noticed cards wearing out. Age doesn't seem to hurt them, the ones I have are 40+ years old and work fine in my HP-67. If they have a limit for how often you can overwrite them, I haven't run into it myself.