Rheological studies of shellac

The melt‐viscosity of shellac at various temperatures, the solution viscosity of shellac and the solution viscosity of several shellac‐based varnishes were investigated using a cone and plate rheometer. The study revealed information regarding yield stress (minimum force required for initiating flow) and thixotropic properties of shellac and shellac‐based materials. Such information will be useful for developing shellac‐based moulded articles and shellac‐based varnish compositions.