Wrap outside of pan tightly with 3 layers of heavy - duty foil. (epicurious.com)
Thoroughly grease the springform and wrap at least 2 layers of heavy aluminum foil around outside of the pan (especially the bottom) to prevent butter from escaping (like life, it will find a way) and water in the later water bath from entering. (illmakeitmyself.net)
Wrap outside of pan tightly with foil (this will help prevent custard from leaking out). (bonappetit.com)