Epopast 400 Specimen Mounts: The Movie

Written by Lu Allington-Jones, Senior Conservator, Natural History Museum London

Epopast 400 is an excellent material for creating supports for heavy specimens. It is a 2-part mixture of a liquid and a fibre-glass putty that has passed accelerated ageing tests. The dough-like mixture can be applied to robust specimens and allowed to dry over night to create a rigid support which allows even distribution of weight and prevents point compression damage.

Presented below you will find a video of how to make support mounts out of Epopast 400, plus some practical tips and things to consider. But first some examples of the uses of Epopast 400 mounts:

Figure 1. This Iguanodon tibia NHMUK PVOR28702 has a double (clamshell) jacket for transportation in a padded crate. ©The Trustees of the Natural History Museum, London.
Figure 2. NHMUK PVR3804 Suchodus brachyrhynchus: A twin layered support reduces the storage footprint (specimen length 815 mm). The whole mount sits on a rigid base of corrugated aluminium (extremely strong but lightweight). ©The Trustees of the Natural History Museum, London.
Figure 3. NHMUK PVOR32599 Pelagosaurus typus: A double-sided mount to allow safe handling and transportation of a very delicate specimen (length 190mm; mount created by A. Bernucci, NHM). ©The Trustees of the Natural History Museum, London.
Figure 4. NHMUK PVM12429a Elasmotherium sibiricum (length 940 mm): The underside of this heavy skull was extremely fragile but the specimen needed a display mount. Delicate areas were protected by adding Epopast 400 to the robust areas and allowing this to dry before using acid-free card bridges to support a second layer of Epopast 400. ©The Trustees of the Natural History Museum, London.
Figure 5. NHMUK PVM12429a Elasmotherium sibiricum (length 940 mm): The engineering team created a display mount using the Epopast 400 support. Once the specimen has been removed from exhibition, the brass rods will be removed, and the mount will be adapted for storage using more Epopast 400.  ©The Trustees of the Natural History Museum, London.

This film stars the elusive @StoatsMcGee and the femur of Loricatosaurus priscus, holotype stegosaur NHMUK PVR3167. ©The Trustees of the Natural History Museum, London.


  • Even distribution of weight.
  • Easy manoeuvring of heavy specimens.
  • Light weight but not brittle like plaster of Paris or Jesmonite.
  • Adaptable for display mounts.
  • Fresh Epopast can be added to cured Epopast at any time.
  • Good for transportation of specimens.


  • H&S issues of Epopast itself – corrosive, sharp edges.
  • Physical mixing can be tiring.
  • You tend to run out of catalyst if you don’t measure it carefully.
  • H&S of grinding the sharp edges down (excellent dust extraction is required). An alternative to grinding the Epopast is coating the mount with a smooth layer such as Tiranti multipurpose polyester resin with a slate filler.
  • Very messy – but can be cleaned up with IMS and tissue before it dries.

Materials list

  • Cling film barrier layer(s).
  • Modelling clay for undercuts.
  • Relic WrapTM (polytetrafluoroethylene film) or aluminium foil barrier layer.
  • Epopast 400.
  • Grinding equipment or polyester resin for creating a smooth finish.
  • Plastazote® 2 mm for lining finished mount (if you want to use 10 mm foam lining, lay a 10 mm layer of modelling clay between cling film layers on your specimen to create a contoured void to accommodate it).
  • Hot glue for attaching Plastazote®.
  • Acrylic paint.
  • PPE (disposable nitrile and marigold gloves, Tyvek® sleeves, lab coat, safety spectacles for mixing). Please always check the manufacturer’s most recent Safety Data Sheet before using any chemical.

Happy ‘pasting’!

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