By Steve FritzingerNova Labs’ Plastics and Composites Steward
A gentleman named Geoff recently contacted me looking for help restoring a family heirloom. His grandfather was an executive at the New York Central System railroad. When NYCS was retiring their steam locomotives, the bells on the front of the engines were prized keepsakes. His grandfather got two bells from two engines. The bells were passed down through the family; today, Geoff and his sister each have one.
Both bells were missing the New York Central emblem. The emblems had been attached to the bells with a steel peg – the combination of cast iron, steel, and whatever the emblems were cast from caused the pegs to corrode. Over time that caused the emblems to crack and crumble. All the bells from that period are missing their emblems.
After years of searching, Geoff finally found one that was in good enough shape he could repair it. He carefully cut an oval from an empty beer can and epoxied the two halves of the emblem to it. Now his problem was he had two bells and only one emblem.
Geoff came to the May Open House. I showed him how to use silicone rubber to make a mold of the piece.
Then we cast two copies in resin using different techniques to get a metallic finish. For the first one, we add aluminum powder to the resin and painted the inside of the mold with more powder. This is called Cold Casting. That didn’t work well. Cold cast pieces must be gently polished to bring out their luster. The surface of the emblem was too rough to polish properly. We couldn’t polish the low spots without removing the shine from the high spots.
We cast the second attempt using just resin. When the piece was fully cured, we applied several layers of Rub ‘n Buff silver leaf finish. That one came out great!
Here’s the replica next to the original. All he has to do is paint the background, weather it a bit and mount it to his bell. He’s going to make a second one for his sister’s bell so he can keep the original safe.
We made a second mold which I’m now using in my Casting for Makers demonstration class to show how to use casting to restore otherwise irreplaceable pieces.
The best part? When I told him we’re an all-volunteer non-profit, he donated $50 to Nova Labs!
Nova Labs is offering Summer Camps for Teen Makers and Youth Robotics!