FIGURE 1. An example of damage caused by air-abrasion on a piece of dinosaur rib bone (unregistered float). The untreated bone surface is in the left-hand half of the image, while the right-hand half has been abraded for 5 seconds with 53µm aluminium oxide powder, delivered via a 1 mm diameter nozzle from 1 cm distance. The abraded half shows significant pitting and complete loss of the bone surface. (304 x magnification SEM image at 20Pa variable pressure and 12 mm working distance)

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FIGURE 2. Powder type and size used by the respondents of the survey. Respondents also reported use of: Iron 150-200 μm, garnet, rice flour 100-200 μm, potato flour 20-200 μm, pumice 50 μm, Armex composite formula, Tantalum beads and calcium carbonate 150-200 μm.

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FIGURE 3. Health and safety precaution responses from the survey.

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FIGURE 4. Twinned SEM images of glass bead powder. Left (4.1): before use. Right (4.2): after single use.

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FIGURE 5. Twinned SEM images of sodium bicarbonate powder. Left (5.1): before use. Right (5.2): after single use.

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FIGURE 6. Four polished limestone samples, painted with Paraloid B72 and copper powder, each showing an abraded central area with a polished copper halo surrounding it, which would not normally be visible with the naked eye.

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FIGURE 7. Comparison between powder types at 50 μm particle size, 30o angle and 30 mm working distance between nozzle and substrate.

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FIGURE 8. Comparison between nozzle angles in relation to the substrate using 50 μm Aluminium oxide powder.

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FIGURE 9. Comparison between nozzle angles in relation to the substrate using 50 μm crushed glass.

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FIGURE 10. Comparison between working distances between the nozzle and the substrate using 50 μm aluminium oxide powder.

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FIGURE 11. Comparison between powder size using aluminium oxide 30o angle and 30 mm working distance between nozzle and substrate.

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FIGURE 12. Comparison between trench scatter halo lengths of the various powders trialled with 30o angle and 30 mm working distance between nozzle and substrate.

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FIGURE 13. Comparison between trench scatter halos with varying angles using 50 μm aluminium oxide powder.

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