#33b: Cast Iron Restoration Illustrated

Perhaps digital scanning and additive prototyping will become more sophisticated, replacing my old fashioned hands-on work, but here's how I have recreated decorative cast iron objects:

This illustration represents a flat surface that is badly pitted and rusted.  You can imagine swirls of acanthus leaves, grape clusters, or even cherubic faces, quite complex surfaces being this damaged by time and atmosphere. There would formerly have been lines and smooth transitions defining the surface.

The great thing about cast iron is that it came from a moulded surface, so finding parting lines and taking moulds from the surface is relatively easy.

I have made the mould transparent to illustrate that the mould picks up all the detail from the surface. I wax the surface quite thoroughly and pour a quick-cast polyurethane over it to create a rigid, sandable surface.

I use Repo One from Freeman, a nice, predictable two-part urethane, one that keeps really well, without reacting to the atmosphere.  Many other resins start to go crusty and bad within days of opening the container.

Here's the plastic mould, shown open. Note how all those pits have become raised bumps. The original surface gradually became more and more pitted. The mould can now be sanded, removing that damage while following original lines and curves. I've worked a lot in the negative, as it's a great way to make detail come alive.

A typical surface, an historic iron gate or post might require many hours of sanding to level out the damage.

And here's the sanded mould in blue, with a copy taken in plastic. This copy is used to produce the new cast iron reproduction. 

In reality, there might be some hours of work on that plastic copy, fairing lines, cutting in lowered detail that was lost, and sharpening features.