Spot welding advice

[bondy]

Hi I've just bought a second hand spot welded just need to know the best way do you need to bare metal all sides and can you use etch primer .

[davemk1]

Try this screwfix product. Item number 31074
It's what I used on mine. Cleans off everything and does no damage to metal whatsoever.
You can buy weld through primer but haven't got a clue how conductive it is as I never used it because my whole shell was electrophoretic primed (e-coated) in a tank after all the fabrication work.

[katana]

Metal should be bare or you can weld if the surface has weldable primer - not regular primer which will isolate the electrodes.