This is a close up of a situation we encountered when doing the underside of the steps in the northwest corner. You can see pieces of metal running through the aggregate that are rusting. We know that the metal rusting will cause a problem if we repair over it, so we get some pliers and start pulling. Most of it came out easily, but a few pieces were running deeper into the structure. We ended up getting the grinder out to nip those pieces off below the rust line. I thought of the rustoleum, but we decided to repair over the nubs. We'll keep an eye on this region of the Stupa next year though...