Exhaust Paste

[drewbie]

Hi, can anyone recommend an exhaust paste that wont go all powery a year later. The inner skin of my back box is fine so I tend to dress up the rusted parts of the outer skin once a year for the mot, but it would be nice if I could fine a paste that hasnt gone white and power like a year later and need digging out before replacing, i've tried all the popular brands.