Car & paint · 1 min read
Sanding and repairing rust bubbles on a car
Open the bubble, remove the rust down to bare metal, feather the edge: P80 to P320 – then primer, primer surfacer, paint.
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Down to bare metal
Under a rust bubble, the rust is almost always bigger than the bubble. Sand with P80 until there is bright, silver bare metal all round – any rust left in the pores will bloom again under the new paint.
If the panel is rusted through or very thin, sanding is no longer the repair: a section of the panel has to be replaced.
Feather the edge
Use P120 and P180 to feather the transition from bare metal to the old paint, so you can no longer feel the step with your finger. Then key the old paint around the area with P240 to P320 so the primer surfacer and paint will adhere.
Protect it quickly
FAQ
Can I just paint over the rust?
No. Rust under the paint keeps spreading and soon breaks through again. It has to come off, right down to bare metal.
Terms in this article
All terms in the sanding glossary →The whole sequence at once
5 grits, 1 × smallest pack each: PRO CUT 150 (10 pcs) P80 · P120 · P180 · P240 · P320.
Or as a set: Car paint starter set (P120–P600) for €69.90 →
incl. VAT, plus shipping
