Produced by Heritage Victoria
Tribal Media Makers
From the interactive exhibition produced by Heritage Victoria Viewbank: Unearthing a Forgotten Colonial Homestead in Melbourne Suburbia.
Heritage Victoria’s Conservator Susanna Collis explains the challenges in conserving the 19th century metal servants’ bells.
Click Here to hear archaeologist Dr Sarah Hayes speak about the history and use of servants' bells at Viewbank.
SUSANNA COLLIS: The metal servant's bells that came to the conservation lab from Viewbank were treated in a very complex way. There were two types of metals that comprise the bells. One was a ferrite, or iron, material. And the other one was a copper alloy, so brass or bronze.
The iron components of the bells were very degraded. There was a lot of corrosion and spoiling. So part of the iron was falling off in bands and spots. The copper-based elements were fairly intact, and so didn't need as much treatment.
The challenge was that these metal components are combined and attached to one another. And that makes it hard, because we need to have a more interventive approach with the iron than we do with the copper.
So to stabilize the iron corrosion, in this case, the conservator undertook a fairly multi-step approach. The first stage of which is brushing off that iron which is going to come up anyway. So to remove the spoiling corrosion. And that's with just a gentle brush. We're not hammering it, or anything like that.
After we remove the spoiling corrosion, it's then treated chemically, just to remove as much other corroded iron as possible from the surface, until we're left with what we think is a fairly stable base metal. After we reach that point, the iron surface was treated with a coating, a conversion coating, like a rust converter, but a little bit different. And so we'd create a stable outer metal surface, to show to the world, that wouldn't deteriorate further.
After that chemical process, then the process was sealed with a coating for iron, which does involve, actually, a little bit of fish oil. They don't smell anymore. But it complexes with the surface and creates an airtight surface with the metal.