When learning how to sand epoxy resin, you may be tempted to pick up a dry piece of sandpaper. However, we strongly recommend that you wet sand epoxy as opposed to dry sanding. There are a number of reasons why wet sanding is the best choice:
Waterproof sandpaper tends to last longer when wet sanding than normal sandpaper in dry sanding.
This technique removes smaller uneven areas straight away.
The moisture of the sandpaper allows for less dust to be produced.
As the dust collects in the water, you will be able to see the surface you are sanding more clearly, thus giving you an accurate gauge as to the progress you have made.