Measurements of the rate of sulfation of powdered pentelic marble at high temperatures (weight gain), of polymer-coated marble at ambient temperature (EPMA), of untreated and polymer-coated marble at ambient temperature (weight gain), and of the rate of attack of sulfuric acid (weight loss) on untreated and polymer-coated marble at ambient temperature, support and provide supplementary evidence for the validity of the model of a galvanic cell for the sulfation of marble and its mechanism as presented in the previous work, and of the danger of using protective organic films which accelerate the sulfation. For parts 1 and 2, see AATA 19-638 and 20-1529. -- AATA