Scanning Microscopy


The present paper describes a two stage impression technique using a silicone elastomer suitable for field replication studies; which requires high dimensional stability, defined resolution, and being capable of reproducing inaccessible details. A test object consisting of etched pearlite possessed fine detail [>1μm to <0.1μm] which was suitable for testing negative/ positive replica combinations. Coltene President light-body impression material was capable of resolving parallel side depressions of widths ≧0.2μm, and it possesses very good dimensional stability with time, allowing the production of positive casts to be deferred for several months. Low viscosity Spurr resin reproduced this detail, and flowed into inaccessible sites.

Although there was evidence of bulk contraction on curing, there was no significant shrinkage on flat [linear] surfaces or in vertical relief dimensions.

Replicas of fractured hominid teeth showed good surface detail, and reproduction of inaccessible three-dimensional features on enamel surfaces. Enamel prism shape was pattern 3.

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