Preserving fossils This presentation looks at the very basic issues of preserving fossils.

The Pterosaur Database When to preserve? If a fossil is hard and stable – do nothing. For shale fossils use PVA solution to bind the surface. For bone fossils consider using hardeners. For pyrite fossils – Keep them very dry. The general rule is that every fossil is different. The Pterosaur Database

The Pterosaur Database 1. Hard stable fossils Brush of and remove soft sediment Wash in mild soapy water Dry with a soft cloth Consider soaking in a weak vinegar solution for about an hour prior to removing hard adhesions. After removal of adhesions, soak in fresh water for an hour. The Pterosaur Database

The Pterosaur Database Notes on Shale fossils Shale is a sedimentary rock that is often stable due to a high water content. If shale dries out, it can lose its integrity and collapse into a fine powder of mineral micro-crystals. To protect fossils preserved in shale, the surface needs to be bound with an adhesive like PVA to a reasonable depth below the surface. The Pterosaur Database

The Pterosaur Database 2. Shale fossils Remove excess sediment and clean appropriately with soapy water. Dry with a soft cloth. As appropriate, paint with a 25%-75% PVA and water solution to bind the surface. When dry, remove excess run off. A number of additional applications may be required. The Pterosaur Database

The Pterosaur Database Notes on bone If bone is sub-fossil (not fully replaced) or only one component of the bone has been mineralised, then it is likely to be brittle and subject to collapse. In such instances, a hardener needs to be infused into the bone to bind the structure and fill micro-cavities. The Pterosaur Database

The Pterosaur Database 3. Bone fossils ** Do not varnish ** Use a hardener like 1 part shellac to 6 parts denatured alcohol. OR resin consolidant like Bitvar B-76 which consists of resin beads dissolved in acetone. Use a water soluble adhesive to join fragments. The Pterosaur Database

The Pterosaur Database Note on Iron Pyrites FeS2 is an iron sulphide mineral which reacts with air and moisture, forming an acidic solution of iron. Over time this will react to break down the pyrites into iron dust and sulphides. This will leave a grey and yellow powder. Melnikovite-pyrites formed at low temperatures are more susceptible to decay. The Pterosaur Database

The Pterosaur Database 4. Iron Pyrites fossils Keep the fossils dry, below 45% relative humidity It slightly affected, brush off dust and keep dry. Where necessary, consult a professional conservator about the technical use of Ethanomine Thioglycolate (Cornish and Doyle Method). The Pterosaur Database

The Pterosaur Database 5. Other options There are lots of preservation techniques. However – if something is very unstable, a cast may be the only option. Casts are also taken before a fossil is physically excavated to show inside details. Take photographs of important fossils to preserve a record of the finds. The Pterosaur Database

The Pterosaur Database References Collins C., 1995, Care and Conservation of Paleontological Material. Boston: Butterworth-Heinemann Parker S., 1990, The Practical Paleontologist, Simon and Schuster http://www.kenmannion.co.uk/fossilpreparationtools.htm http://preparation.paleo.amnh.org/28/bibliography Preparation and conservation skills are often closely guarded by museum professionals in order to allow them to develop levels of expertise and gain continued employment. The Pterosaur Database