Q: I’ve made some large sculptures, and I want to site them outdoors. Do I need to make a foundation for each one? That seems like it would be astronomically expensive. Do I have to bury part of the piece in the concrete while it’s wet?
A: A sculptor should always (and this becomes more critical with large pieces), be sure that a piece is securely mounted. People tend to take offense when one’s work of art wipes out one or more of their children, even if they were told not to climb on it.
In garden and other outdoor settings, where the earth is soft, it is customary to pour concrete foundations when siting sculpture, sufficient to secure the item being displayed even in the most adverse possible circumstances. It is better to overestimate than to underestimate the amount of concrete needed to counterbalance destabilizing forces such as gravity, wind, erosion, and children.
It need not be very expensive if you do the work yourself. Build a form with recycled plywood, or find a scrap section of Burke (or Sono) tube, mix the concrete yourself in a wheelbarrow, and it would be cheap. What’s astronomical is the damages you would be liable for if your sculpture fell over and harmed somebody even slightly…
You can either cast some vertically protruding rods into the foundation which slide into corresponding holes in the sculpture, or cast tabs or studs in the concrete which bolt to tabs in the sculpture, or have rods protrude from the sculpture that cement into voids in the base. Wait for the foundation to set before installing the piece. If you are in a hurry, use Quickcast or another fast-setting concrete mixture.
As with any concrete project, the foundation must cure slowly, so if it’s dry where you are, keep the new concrete damp for the first month or so. As a generalization, a tripod has natural stability, so three footings evenly spaced are an efficient way to impart it a sculpture, but depending on the configuration of your piece, you could use a dozen smaller footings or one huge one—the basic idea is just to give the whole piece a stable base. Thus you will need less concrete if the footings are at the periphery than if they were—or it is—all in the center. Dramatic cantilever effects must be carefully calculated in order to work, and in larger projects the advice of a structural engineer should probably be solicited.