Tumbling tumbleweed

In an effort to create tiny holes in our molded rubber parts, we made these small salt crystals by adding concentrated saltwater to alcohol, which is a poor solvent for salt. Right away, it starts to snow 25-micron cubes. The cubes are added to liquid rubber, then dissolved out in water, creating voids–an approach that other groups have used successfully with larger particles like sugar, table salt and rock salt. But can you spot something that isn’t a cube? We had some acrylic microspheres show up in this electron microscope sample, the same material that’s used in acrylic manicures. We were checking out this acrylic powder as another type of sacrificial material to make tiny holes. These plastic spheres charge up easily and seem to get everywhere.