Styrafoam cement covered rocks???

[MonkeyMonk86]

Does anyone know how long it takes to cure them. I've seen some YouTube videos on 3D backgrounds made that way. They all mention a curing ( water exposure ). Does anyone know how long to soak them after you make them. And are the cement dies really safe?

 

[jwh0818]

They are safe and you have to cure them or your ph will rise very very high. I'm not sure of the cure time