Because people have a need to glue things to other things
Plastic to StyrofoamFor the strongest bond we recommend:
There are so many kinds of plastic its hard to give advice here that applies to them all. If possible try a small test in an area that doesn't show.
Styrofoam is a plastic that has been whipped up like a milkshake and then cured that way. That's what makes it light. Like plastic, there are many different formulas for styrofoam. They may contain any combination of styrene, urethane, neoprene or vinyl. For this reason choosing the correct adhesive is not easy. For our tests we used polystyrene which is a composition of styrene, chlorodifluoroethane and ethyl chloride, for those of you who care. The most important things to remember when choosing an adhesive for styrofoam are:
- Never use an adhesive that contains a solvent. It will erode the styrofoam releasing all sorts of toxic fumes
- Choose adhesives that are suited for not porous materials (remember styrofoams are plastics and plastics are non-porous)
- Never use hot glue directly on to styrofoam. There are some cases when hot glue is an appropriate adhesive, but it should be applied to the material you are bonding the styrofoam to and left to cool a few seconds before contacting the styrofoam. The glue will get lost in the hole that it has burned, and burning plastics releases toxic fumes.
- Remember, a glue is only as strong as the weakest material in the union. Styrofoam is easily broken and has very little tensile strength. In our tests, if the styrofoam broke before the bond, the glue was considered strong enough.
Some plastics have a smooth surface finish that can be sanded off with a 120 grit sand paper, for better adhering properties.