Gorilla Glue is a moisture activated, foaming and expanding polyurethane glue.  One drop of Gorilla Glue will foam and expand 3 to 4 times in volume.  This is why tight clamping pressure is vital to the success of our glue.  Without appropriate clamping pressure, the foaming action of the glue may push your pieces apart.  Your clamping pressure must be evenly distributed across your surfaces.  Perhaps put some plywood sheets across the top of your surface and then place the weights on top of that. 

When using pine, we recommend that you apply water very carefully and only dampen one surface lightly, apply the Gorilla Glue to the other surface and then clamp your surfaces together tightly.  All pine types contain a natural resin/oil, but it glues up well because it has such an open cell structure.  The only difference is if you are using a Yellow Pine which has a very high oil content which tends to liquefy easily.  We recommend you wipe the surface with solvents before gluing and you extend the clamping time when gluing this species of wood.  If too much glue is applied, you will get some squeezing out between your two surfaces.  This can be wiped away when wet using a dry cloth, or paint thinner.  Once cured, you will have to sand or scrape it off since there is no solvent.