An aqueous dispersion comprising: 30 to 70 weight % non-melt-processible fluoropolymer particles having a standard specific gravity of less than 2.225, said fluoropolymer particles comprising a core of high molecular weight polytetrafluoro-ethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene, wherein the average melt creep viscosity of the polytetrafluoroethylene of said core is greater than 1.2 x 10 10 Pa·s and wherein the average melt creep viscosity of the polytetrafluoro-ethylene or modified polytetrafluoroethylene of said shell is greater than 9 x 10 9 Pa·s and is at least 0.1 x 10 10 Pa·s less than the average melt creep viscosity of polytetrafluoroethylene of said core; and 2 to 11 weight % surfactant based on the weight of said fluoropolymer comprising a compound or mixture of compounds of the formula: R(OCH 2 CH 2) n OH wherein R is a branched alkyl, branched alkenyl, cycloalkyl, or cycloalkenyl hydrocarbon group having 8-18 carbon atoms and n is an average value of 5 to 18; said non-melt processible fluoropolymer particles being obtainable by a batch polymerization process in a stirred autoclave involving precharging deionized water, saturated hydrocarbon having more than 12 carbons which is liquid under polymerization conditions and a dispersing agent (fluorinated surfactant) to the autoclave, deoxygenating, pressurizing the autoclave with tetrafluoroethylene to a predetermined level, agitating, and bringing the system to the desired temperature, whereafter said polymerization is carried out in a first stage to form the core during which a first amount of free radical initiator and additional dispersing agent are added and additional tetrafluoroethylene is added to maintain pressure, and a second stage during which a second amount of persulfate free radical initiator and a telogenic agent are added and, for modified polytetrafluoroethylene, a comonomer, said first amount of initiator producing polytetrafluoroethylene having an average melt creep viscosity greater than 1.2 x 10 10 Pa•s, and said second amount of initiator being at least 10 times said first amount, said second amount of initiator and said telogenic agent being added before 95% of the total tetrafluoroethylene has been polymerized, said second amount of initiator producing polytetrafluoroethylene or modified polytetrafluoroethylene having a melt creep viscosity greater than 9 x 10 9 Pa•s and less than the average melt creep viscosity of the polytetrafluoroethylene of said core. 30 to 70 weight % non-melt-processible fluoropolymer particles having a standard specific gravity of less than 2.225, said fluoropolymer particles comprising a core of high molecular weight polytetrafluoro-ethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene, wherein the average melt creep viscosity of the polytetrafluoroethylene of said core is greater than 1.2 x 10 10 Pa·s and wherein the average melt creep viscosity of the polytetrafluoro-ethylene or modified polytetrafluoroethylene of said shell is greater than 9 x 10 9 Pa·s and is at least 0.1 x 10 10 Pa·s less than the average melt creep viscosity of polytetrafluoroethylene of said core; and 2 to 11 weight % surfactant based on the weight of said fluoropolymer comprising a compound or mixture of compounds of the formula: R(OCH 2 CH 2) n OH wherein R is a branched alkyl, branched alkenyl, cycloalkyl, or cycloalkenyl hydrocarbon group having 8-18 carbon atoms and n is an average value of 5 to 18; said non-melt processible fluoropolymer particles being obtainable by a batch polymerization process in a stirred autoclave involving precharging deionized water, saturated hydrocarbon having more than 12 carbons which is liquid under polymerization conditions and a dispersing agent (fluorinated surfactant) to the autoclave, deoxygenating, pressurizing the autoclave with tetrafluoroethylene to a predetermined level, agitating, and bringing the system to the desired temperature, whereafter said polymerization is carried out in a first stage to form the core during which a first amount of free radical initiator and additional dispersing agent are added and additional tetrafluoroethylene is added to maintain pressure, and a second stage during which a second amount of persulfate free radical initiator and a telogenic agent are added and, for modified polytetrafluoroethylene, a comonomer, said first amount of initiator producing polytetrafluoroethylene having an average melt creep viscosity greater than 1.2 x 10 10 Pa•s, and said second amount of initiator being at least 10 times said first amount, said second amount of initiator and said telogenic agent being added before 95% of the total tetrafluoroethylene has been polymerized, said second amount of initiator producing polytetrafluoroethylene or modified polytetrafluoroethylene having a melt creep viscosity greater than 9 x 10 9 Pa•s and less than the average melt creep viscosity of the polytetrafluoroethylene of said core.