An analysis of different polyvinyl alcohol films dyed with Malachite Green is presented. Absorbance and diffraction efficiency of holographic gratings are compared, taking as a parameter the molecular weight and hydrolysis degree of the polymer. It is observed that, using the same dye concentration, the absorption coefficient of the films increases as the molecular weight increases. The absorbance of these plates can be modified when exposed to UV light. In addition, it is found that for holographic recording there is an optimal dye-polymer system film.