One of the most crucial steps in the in the process of making chocolate is defined by this measurement: 30 microns.
That is the width of a chocolate particle that has been adequately smashed and compressed so that it won't feel gritty or rough in the mouth.
An average human hair, on the other hand, is about 100 microns wide.
Chocolate makers spend thousands of hours grinding their chocolate and mashing it with the sugar and milk to completely break down the chocolate particles so the final product is creamy and smooth. Some get the chocolate particles as small as 15 microns across. To do this they use refiners, enormous rollers that crush the chocolate paste into smooth, delicious chocolate.
After this the chocolate is conched, rolled and mixed even more to drive off any remaining moisture. Sometimes the chocolate will be conched for days - swept back and forth by enormous paddles. We were fascinated by both these steps at Scharffen Berger - it was hypnotic watching the grinders stir and mash such huge amounts of dark, fragrant chocolate.