About the service
I make plaster and resin study copies of fossils for school and club sets, and every piece leaves my bench marked as a copy on the back. A cast is a teaching object, never an item to be passed off as a genuine specimen, and I say so in the description that travels with the box. I take moulds only from material the customer has the right to supply; museum-held pieces need written permission from the keeper of the collection, and I ask for it before I quote a date.
Work starts with the specimen itself. I look at how sound the matrix is, whether the shell is flaking, whether there are old glue repairs, wax or salt bloom. Powdery and porous surfaces get a reversible consolidant, then a thin separator layer — not for my convenience, but so the rubber releases cleanly and the original goes home exactly as it arrived. The mould is platinum or tin-cure silicone in a rigid jacket; I plan the parting line along the shallowest undercuts and put the vents over the whorl of a coiled shell and over the sharp ribs of an imprint, because that is where air stands.
Casting is in dental-grade gypsum, or a filled polymer when the set will be handled by a hundred pairs of hands a term. Bubbles are beaten by three things at once: the mix is degassed under vacuum, a first thin detail coat is brushed into the finest sculpture, and the pour goes slowly down one wall so the air walks out ahead of the material. Tinting is built in translucent layers over a ground toned to the parent rock: overall body colour, a darker wash pulled back off the high points, then a dry-brushed highlight along suture lines and growth ridges, so the relief reads from the back row under ordinary classroom light rather than only in raking light.
What a class set includes:
— a silicone mould of your specimen, kept on file for repeat runs
— the agreed number of casts, each stamped COPY and dated on the reverse
— tinting matched to the parent rock and a matt protective seal
— printed labels: taxon, geological period, locality
— a compartment box with a seat for every cast
Work starts with the specimen itself. I look at how sound the matrix is, whether the shell is flaking, whether there are old glue repairs, wax or salt bloom. Powdery and porous surfaces get a reversible consolidant, then a thin separator layer — not for my convenience, but so the rubber releases cleanly and the original goes home exactly as it arrived. The mould is platinum or tin-cure silicone in a rigid jacket; I plan the parting line along the shallowest undercuts and put the vents over the whorl of a coiled shell and over the sharp ribs of an imprint, because that is where air stands.
Casting is in dental-grade gypsum, or a filled polymer when the set will be handled by a hundred pairs of hands a term. Bubbles are beaten by three things at once: the mix is degassed under vacuum, a first thin detail coat is brushed into the finest sculpture, and the pour goes slowly down one wall so the air walks out ahead of the material. Tinting is built in translucent layers over a ground toned to the parent rock: overall body colour, a darker wash pulled back off the high points, then a dry-brushed highlight along suture lines and growth ridges, so the relief reads from the back row under ordinary classroom light rather than only in raking light.
What a class set includes:
— a silicone mould of your specimen, kept on file for repeat runs
— the agreed number of casts, each stamped COPY and dated on the reverse
— tinting matched to the parent rock and a matt protective seal
— printed labels: taxon, geological period, locality
— a compartment box with a seat for every cast
