Scorpion Paperweight (blue)

This unfortunate scorpion is entombed in a bubble of transparent plastic with a pearlised blue base, and is being used for weighing down paperwork, or as a slightly alarming ornament. It is stuck to a disc of synthetic felt to protect your desk. The plastic is a two-part synthetic liquid casting resin – usually acrylic or polyurethane. In its liquid state it’s a monomer, which is mixed with its chemical curing agent or catalyst, and poured into a mould containing the scorpion. As the resin hardens, it ‘polymerises’ into a polymer. The chemical exothermic reaction causes the plastic to heat up as it cures, making most casting resins unsuitable for waxy or other low melting objects. Just before the clear resin is hard, the maker would pour in another thin layer containing blue pigment and some sort of pearly powder, to give the paperweight that sea-bed effect. 

The mould used for the bubble shape was probably made from silicone rubber, which allows the object to emerge clear and shiny, with no need for polishing. Resin is not a pleasant substance to work with, as it gives off irritating chemical fumes which are very smelly. Earlier types of resin tended to go yellow, brittle or cloudy with age and exposure to the UV rays in daylight, ruining many a museum display, but more modern formulations will stay clear and hard indefinitely.