We often get asked if the Corten Steel Planters will stain the adjacent area by producing rust runoff or by being in direct contact with the surface the planter sits on. Below are some pictures of a Corten Planter that has been weathering in the same spot on the patio for about four months. The outside of the planter is completely covered with rust and the patina will act as a protective layer and prevent any further corrosion on the outside walls of the planter. From the pictures you can see that there is very little rust run off (virtually none). At this point the planter is weathered and the weathering steel should produce very little to no rust run off. A point to consider is that Corten Steel (weathering steel) seals and fully weathers best when it is repeatedly exposed to moisture and then is allowed to dry. Thus the amount of rust run off could vary by climate. As a reference the planter in the pictures is happily weathering in Seattle.