Workers from Amex, a Boston-based painting firm, apply a base coat of white to Tank 118 at the Sprague Energy oil terminal in South Portland on Monday. At the same time, an “abrassive blaster” crawls up the tank, removing the rust and old base coat and revealing naked steel. The work is being done to prepare the tank to join “Art All Around,” a project of the Maine Center for Creativity that will create the world’s largest public art installation on the tanks at Sprague Energy. The center this week formally launched its final fundraising push for $350,000.