The effects of salt, water, and temperature on the cross-linking of peptones with glutaraldehyde were studied. At low reaction temperatures, amine groups from peptones form Schiff bases with carbonyl groups of glutaraldehyde. The resulting C=N bond is weak and can be easily broken by heat or dissolution in water. As the reaction temperature is increased, the more stable C-N bond is formed. A network with low water solubility and significantly improved thermal stability is produced. The presence of salt (sodium chloride) increases the miscibility of peptones and glutaraldehyde solution but also increases the water solubility of the final product. The presence of water also has a dual effect. Water acts as a medium to disperse peptones into glutaraldehyde and is also a hydrogen source to drive the reaction forward. However, water is a byproduct of the reaction. Its presence suppresses the reaction from the standpoint of thermodynamic equilibrium, and it must therefore be driven off (by heat).