ASNT Level III- Visual & Optical Testing
My Level III Self Study Notes Reading 4 Section 4B
My Level III Self Study Notes Reading 4 Section 4B
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5.2.1 Use of Silicone Replicating Materials<br />
Silicone replicating materials are supplied in two parts: a base material and<br />
an accelerator. Although it is best to follow the recommended mixing ratios,<br />
these can be altered slightly to change the working time of the material. The<br />
two parts are mixed thoroughly and spread over the subject area. Additional<br />
material can he added to thicken the replica. Molding clay can also be used to<br />
build a dam around a replicated area. The dam supports the replica as its<br />
sets and allows thicker replicas to be made. Measurements of pit depth and<br />
surface finish can be obtained easily because of the silicone's ability to flow<br />
into crevices on the test object. To evaluate pit depth and surface finish, the<br />
replica is cut and the cross section is examined with a microscope or a<br />
macroscopic measuring device (a micrometer or an optical comparator).<br />
Charlie Chong/ Fion Zhang