A foaming additive and a catalyst additive may be used to foam polymeric materials having a low melt flow rate. The foaming additive may include a blowing agent and a hydrophilic component, and the catalyst additive may include a catalyst and a hydrophilic component. Since both the blowing agent and the catalyst are initially combined with a hydrophilic component, the blowing agent and the catalyst are able to find each other easier after being added to the polymeric materials. This makes it simple and economical to make low density foamed materials using polymeric materials having a low melt flow rate.