May ’22

Plastic Skulls

The objects are a group of plastic skulls which form part of the Oriental Museum collections in Durham. Based on comparative examples of anatomical models found on antiques websites, as well as the history of the Deutsches Hygiene Museum Dresden, for which several of the models have distinct tags, these specimens were likely manufactured in the 1960’s.

The invention of plastic in the early twentieth century was an asset in studying anatomy. Starting in the 1940’s, the Dresden Hygiene Museum began to manufacture a wide range of plastic anatomical models, which were then used both within the museum as well as exported to educate the public about the human body (Deutsches Hygiene Museum Dresden, Sammer, 2015). These early hominin models are no longer produced by the museum, suggesting that their manufacture was limited to the 1960’s.

These models were intended to be used for teaching purposes, to clearly demonstrate the anatomy of early hominids in comparison to two-dimensional drawings, as visual instruction through exhibition grew more common. These models were intended to “simplify” the complex, scientific notions of anatomy and history to drive popular education and understanding.

Condition

• Sellotape had been wrapped around three of the skulls and was now discoloured and deteriorating
• There was a light layer of museum dust on the surface
• Two of the skulls were unnatural in colour.

Conservation

Initially, all Sellotape was manually removed from the Cro Magnon, La Chapelle, and Chimpanzee models. This was achieved using scissors and by hand. Unfortunately, this process left a layer of sticky residue on the models. The residue was not an issue for Cro Magnon and La Chapelle models, as this residue would mostly be covered by a layer of paint. However, the chimpanzee model required adhesive removal. This was primarily achieved using a bamboo skewer, though not all the residues could be removed due to the risk of scratching the paint surfaces which would leave plastic exposed for further degradation. Solvents were not considered for the adhesive removal process as they were likely to cause damage to the paint and plastic surfaces .

All general soiling was removed with the use of a large soft bristle brush and a rubber eraser. Although there was an attempt to remove the degraded plastic from between the springs of the chimpanzee model using a dental pick and a scalpel, this was deemed to not be possible, and the conclusion was made that this material would not lead to any serious degradation.

In order to repaint the Cro Magnon and La Chapelle models, the detail areas were taped off with masking tape before the surfaces were airbrushed with Golden High Flow Acrylic Paint. During this process, paper labels were protected using a small amount of melinex to ensure their retention.

After this, the tape was removed, and details were added by hand using acrylic paints to create definition in the surfaces and delineate areas of loss visible on the original skulls. The models were then airbrushed using an appropriate coating in order to protect the paint.. The flaking grey paint of the Rhodesier model was repainted by hand in a more neutral tone using Golden High Flow Acrylic Paint as a base. The recolouring allows the skulls to look more natural, assisting in their use as teaching materials.

Stay tuned for next month’s object!