Casein, a milk protein, is commonly used for bonding transformer boards. These are cellulose-based substrates used for insulation of transformer components. Even though being used over decades, the microstructural features of the protein which contribute to the casein-cellulose adhesion is less understood. Casein as a protein, is very sensitive to the processing conditions experienced during adhesive processing and bonding. These changes in the environmental conditions such as pH, temperature and ionic strength can in turn can also affect its adhesion properties. It was observed from the studies that the secondary structures and the effective packing of casein particles can vary depending on the concentration, pH and temperature of the casein dispersions. These structural changes were also found to affect the wetting and adhesion of casein dispersions with cellulose-based substrates. Secondary structures such as β-sheets and random structures were found to be more favorable rather than α-helices for casein-cellulose adhesion. The conformational changes are mainly controlled by the pH and temperature during processing. Hence the adhesion properties of casein can be tuned by controlling the processing conditions. To enhance the processability and adhesion properties of casein dispersions, several natural additives such as carboxymethyl cellulose and natural gums were also added to casein. These casein formulations were found to have excellent adhesion, rheological, mechanical and electrical properties which are comparable to that of commercial grade glue.