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This stuff is your basic Polystyrene cement, and works by melting plastic parts together, using the solvent that is the majority of what makes this product (acetone). As the acetone evaporates, the plastic parts regrow polymer chains, resulting in a solid bond between the parts. While you could easily make your own cement from acetone and Styrofoam, it's much more convenient to use a commercial product. You can also depend on this to be uniform from jar to jar, which can be very important on a large project. The product is supplied in a glass bottle, and with a tightly fitting cap. It should have a long shelf life, because of the good seal on the cap. The cap also contains a brush applicator, which is handy, and saves you from having to find a brush each time you use it. Highly recommended. This one is the best.