I am having a hard time figuring out how to make slurry. I've poured
countertops in pre-set forms, and I've got little air holes on the
edges. I need to fill them in with slurry, but I don't know how to
make slurry.

I know it is portland and water. Very fine sand can be used, but I've
heard I should use acrylic, plasticizers, or something else.

Can anyone clear this up?

Thanks.