A method for preparing a vacuum insulated panel includes forming an internal cavity between a liner and a wrapper and preparing a filler material to be disposed in the internal cavity. The filler material includes a first part and a second part and is prepared by treating a surface of the first part. A coating is applied to the surface of the first part with a chemical having a first charge. The coating forms a first surface charge on the surface of the first part. The method further includes mixing the first part with the second part forming the filler material. The second part includes a material having a second surface charge opposite the first surface charge.