2017-11-13 Building SV Satoshi - Wharram Tiki 38

In this video I am making a box for the storage of the epoxy at a temperature of around 20 degrees celcius. After that I continue with my epoxy experiments. I sanded some test pieces with 80 grit sandpaper. I was quite surprised about how much of the coating was removed. I am wondering if this is normal or am I sanding too much before applying a new coat?