how after restoration of heavily rusted metal objects, they still have so much metal left

Question

I’ve seen a number of videos recently of people restoring very rusted objects, like toys and an anceint historical knife, where the rust seems to have eaten most of the metal. However, after restoration, the object seems good as new and don’t seem to have lost any significant amount of mass even though you’d expect there to be nothing left. How is this even possible?

In: 3

Answer 1

There are several types of rust actually, and they don’t al penetrante the metal in the same way. Therefore, some steel types just seem to disintegrate while others remain mostly intact. It all has to do with the alloy and surface treatment or annealing it underwent.