The Mini’s fuel tanks were a bit rusty on the inside, a situation not all that unexpected on a 50 year old car. Fortunately, there’s a brilliant and fun way of restoring them; electrolysis!
There’s an in-depth guide to electrolytic rust removal on Andy Westcott’s page, which was enormously helpful. Brian used a length of steel reinforcing rod as the sacrificial anode, and a high current 5 volt power supply (a computer power supply is perfect).
After about a week of electrolysis the fuel tanks were looking much tidier inside.
A good slosh around with POR15 fuel tank repair kit, and they’re better than new.
Now for the outsides. What looked like slightly faded black paint turned out to be thinly applied underseal, hiding a very even coating of surface rust. *Sigh*.
The sandblaster made short work of the rust…
A coat of etch primer, then epoxy enamel, and we have two gorgeous fuel tanks.