Drying/transportation and releasing MFC

A method of forming an aqueous solution comprising microfibrillated cellulose, the method comprising the steps of:

• providing a substantially dry composite material, comprising microfibrillated cellulose and a filler material, wherein said filler material is precipitated onto fibers or fibrils of said microfibrillated cellulose;
• providing an aqueous media,
• wherein the method further comprises the steps of:
• lowering the pH value of said aqueous media to a level at which the filler material decomposes by a method consisting essentially of adding an acidic agent, wherein the acidic agent is any one of hydrochloric acid, sulfuric acid, citric acid, phosphoric acid, and nitric acid,
• mixing said aqueous media with said substantially dry composite material, before, at the same time as, or after the step of lowering of the pH,
• such that the filler material precipitated onto the fibers or fibrils of said microfibrillated cellulose decomposes and generates carbon dioxide releasing said microfibrillated cellulose.