If the wall is primed you can put up tape and plastic. If not a spray shields can be used. Though I have had large jobs where we just spray and then have 2 guys follow with 10" knives wiping the walls a soon as its sprayed then clean the top angle with a 6"
Not sure why you would use silica sand in your mix. There are applications that call for glass (really just plastic) but the ceiling is sprayed then glass or diamond looks is applied with a small hopper. Same process for silver or gold glitter . Easiest way to find out what it would look like is to do a test run on a scrap piece of sheetrock.
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