Can anyone tell me how to cast rocks on styrofoam so that they would bond to the styrofoam?
I would like to use plaster of paris in aluminum foil crumpled to stick on styrofoam. Is there anything I have to do special to accomplish this?
Will be looking forward to hear from any model railroader that has done this procedure before.
I thank you - model railroaders - if you can help me out on my question.
You could either cast them onto the foam, or cast them, let them dry, and glue them to the foam. Nothing special, just do what common sense tells you.
Welcome to the forums!
As stated above you can do either. The video I have seen put plaster cloth over the foam to help with the adhesion for damp (direct) applications. Latex caulk will hold dried ones in place right on the foam. If you are going to use the damp method do a couple pratice pieces, especially if you are going to be doing a vertical, curved casting. Have seen it said you have to do it at the right point of plaster setup, just when it cracks on the back a little as you flex it, I think. I have one planned, both sides of a cut. Be sure to spray a little wet water onto your form before pouring your plaster into it, will release better. I have seen some very spectular rockwork done using foil as the forms.
Good luck,
For added insurance for a good bond when doing the “wet mold” installation, Mix a small batch of plaster to butter up the mold as you press into place. If you allow the plaster to set just a bit too much, you may not achieve a solid bond to the foam.
This method will work better on extruded foam over the beaded styrofoam.
If you would like some other options and far better detail of the rock castings, consider the use of rock molds. Although I have seen some very good “crumpled foil” work, the proper pick and placement of decent castings from production molds will produce a more convincing look.
Gluing, screwing or nailing fine wire screen to the foam will also help with adhesion.