Carbowax is a water-soluble wax which can be used as a temporary support, and as a consolidant in both prep-work and fieldwork. It melts at low temperatures, and dissolves in water.
It can be used as a temporary support for fragile structures, for temporarily embedding a specimen for mechanical preparation, or for protecting structures like spines during shipping.
PEG 4000 (Polyethelene Glycol) - this grade is relatively hard. It can be chipped away during mechanical preparation and holds its shape, without being too hard and brittle.
Preparing the Carbowax
Melt at a low-medium heat and allow to partially cool. Either pour into a mould or drop onto the space required. Plasticine can be used to help contain the molten wax, as can homemade cardboard molds. Do not overheat.
Carbowax can also be used as a temporary consolidant in fieldwork, allowing the temporary support and excavation of fragile specimens that can’t be removed without being embedded. Surround the rock in a material like platiscine and pouring melted carbowax into the mould. Remove plasticine when the carbowax is removed. Slowly melt the carbowax to remove.
It is often used in marine archaeology for preservation of timber. There are very few approaches that can be used to recover wet and fragile speicmens from moist environments. However, in this instance it wouldn’t be considered reversible as it is likely the specimen would fall apart without the carbowax binding it.
It can be used as a structural support for spines or other delicate features during preparation. Smaller specimens can be entirely embedded in Carbowax for strength and rigidity during mechanical preparation, which means you can prep both sides (e.g. microvertebrates). It can also be brushed on to fill holes and pores. Cracks can be temporarily filled for stability. Plasticine can be shaped to create a container for the Carbowax, which can be removed when the Carbowax has set.
Protective Packaging and Transportation
Carbowax is also useful to protect fragile features like ammonite spines during shipping and transportation, as the recipient simply has to soak the fossil in warm water to remove. It can also be used to help safely transport fossils from the field back to the workshop.
Removal When finished, simply place the fossil with the wax in warm-hot water (approx 75°C) and the wax will dissolve. You can also chip away most of it first or remove entirely mechanically if it is safe to do so. Run through a coffee filter first if there are bits of matrix in it. To recover and reuse the wax, wait for the water to evaporate at room temperature and collect.