Power grinders and wire wheels leave scratches on the surface. Waxing is a reversible process. The wax should flow easily when applied to the warmed object without having to melt the wax first. Observe safety precautions. Wipe off excess wax when the item has cooled.
Microcrystalline wax is available from conservation supply businesses.
Silicone can also be used by spraying or rubbing it on. Avoid application to any wood surface, as silicone may interfere with refinishing the wood and is not easily removed. If your iron keepsakes include old wagons or farm machinery, etc., which were traditionally painted, rust-inhibiting paints may be used. Determine first the original color and design and whether painting will affect the antique value of the item. If the item can be protected without the addition of paint, the item may be best left alone.