a continuous process for manufacturing a polyester includes introducing reactant components including a terephthalic acid slurry having an ethylene glycol to terephthalic acid molar ratio of about 2 and a tio 2 slurry to an initial reactor vessel and stirring the reactant components at greater than 0 to 200 rpm to form an oligomer ; transferring the oligomer , phosphoric acid , and at least one additive to an intermittent reactor vessel and stirring at 400 rpm to 1000 rpm to form an intermediate , wherein the oligomer , the at least one additive , and the phosphoric acid have a residence time of from 1 minute to 5 minutes in the intermittent vessel ; and polymerizing the intermediate in a final reactor vessel at a temperature of 285 ° c . to 320 ° c ., and in the absence of a polyethylene glycol , to obtain the polyester .