Abrasives are an important but rather traditional technology. Grinding wheels, abrasive papers and loose powders all exploit tiny particles of grit made by crushing larger chunks of the material. These grains tend to be roughly spherical; few have any acute, sharp cutting edges. Worse, their orientation in use is entirely random. Only a tiny minority do anything to shape the workpiece at all.
Daedalus now wants to make sharp and spiky abrasive particles directly. He points out that gases conduct heat very badly. Thus a snowflake growing in air cannot readily get rid of its latent heat of condensation. Its points and edges are much better cooled, and therefore grow much faster, than its core. Hence the highly branched, dendritic form of snowflakes. Accordingly, to make an ideal sharp and spiky abrasive powder, condense it from vapour in a large mass of air or inert gas. Indeed, when some metals (such as zinc) burn in air, the resulting smoke consists of fine, highly branched and pointed single crystals of metal oxide.
This is a preview of subscription content, access via your institution
