I have a bag of powerhouse cement I mix with water, it makes a mortar looking and acting goop for cementing in a smoke pipe to the chimney, or other boiler spots that need sealing. Sets up like cement, but if I have to move something I just break it out, add water, and reuse it. I know I have some that's been reused a dozen times.
There's the white liquid stuff you add to cement for laying a thin coat, like filling a hole that tapers to nothing. Strengthens the thin parts so they don't snap when you walk on them. Maybe they could add a little to the sand to make it hold it's shape.
We had a 55 gallon drum of a liquid to mix into the casting mold sand for better detail when the pattern was pulled. No label, no cautions, no name, but it didn't seem to bother any of my 16 fingers.
