By Sue Bassett
While the Trust’s on-ice conservators move the artefacts from the historic expedition huts to the laboratory at New Zealand’s Scott Base in Antarctica for thawing, documentation and treatment, there are also immovable items that require in situ treatment in the huts.
One such case was that of the cast-iron galley stove at Captain RF Scott’s hut from the British Antarctic ‘Terra Nova’ Expedition 1910–13 at Cape Evans. For the Trust’s metals conservators, it didn’t seem too daunting – mechanically remove corrosion, chemically convert corrosion, apply protective coating to surfaces. Straightforward, right? Well, not quite – this is Antarctica, after all.
First problem – removing the corrosion was going to create a lot of ‘rust dust’. So a tent of scaffolding and clingwrap film was erected to contain it, with doors of polyethylene sheeting to enable repeated access.
Second problem – the chemical reactions required to convert and stabilise the corrosion failed to work in the sub-zero temperatures. At first it was thought that deposits of fatty seal blubber on the metal surfaces may be interfering with the reaction, but no amount of scrubbing and degreasing achieved a successful result. And tests back at the lab indicated that it was indeed a temperature issue, combined with extreme dryness that caused rapid evaporation of the solvent in the solution, leaving a deposit of powdery solute on the metal surfaces.
The solution? Heat the metal using hot air from a glycol heater, after encasing the entire stove in blankets to minimise heat loss. And, despite some discomfort for the conservator working under the blankets with blowing 60°C air, it worked a treat and the results were worth the pain.