Stone chips and minor scratches are inevitable on any vehicle – especially the front bumper, bonnet, and lower doors that are exposed to road debris. Treating them promptly with touch-up paint prevents rust forming under the paint and keeps the vehicle looking presentable. The result will not be invisible but is much better than leaving the bare metal exposed.
Why Treat Stone Chips Promptly
Once the paint is breached and bare steel is exposed, rust forms within days in humid coastal areas, weeks in dry inland areas. Once rust starts under the paint, it spreads laterally and lifts the surrounding paint over time. A small chip becomes a larger rust spot. The 5-minute job of touching up a chip when it is fresh saves hours of rust treatment work later.
Getting the Right Paint
The paint code for your vehicle is on a sticker – usually on the door jamb, in the engine bay, or in the boot. Note the colour code (a 3 to 6 character alphanumeric code) and any second code if it is a metallic or pearl finish. Order touch-up paint matched to this code from the dealership or specialty suppliers like Octoclean, Auspaint, or Australian Touch-up Paints. Generic “close enough” colours from auto stores rarely match well, especially on metallics.
Preparation
Wash the area thoroughly with car shampoo and dry. Inspect the chip – if there is any rust, it must be removed before painting. Use a fine pick or a small brass wire brush to remove rust from the bare metal. Wipe with isopropyl alcohol or panel wipe to remove all contaminants. The bare metal must be perfectly clean and dry. If the chip has loose paint flakes around it, gently remove them so the touch-up paint adheres to a stable surface.
Application
Use a fine brush or toothpick (the brushes that come with most touch-up paint bottles are too coarse for small chips). Apply paint sparingly – several thin coats are better than one thick blob. Let each coat dry for at least an hour before adding the next. Build up the paint level until it is just below the surrounding finish (it is better to be slightly low than slightly proud). For metallic paints, apply the colour coat first, let dry, then apply a clear coat over it.
Levelling and Polishing
After 24 to 48 hours of drying, the touch-up paint can be very carefully wet-sanded with 2000-grit paper to bring it level with the surrounding paint, then polished with a fine cutting compound. This step requires care – sand too aggressively and you cut through the surrounding clear coat. Many DIYers skip this step and accept a slightly bumpy repair, which is invisible from a few feet away.
Larger Chips and Scratches
For chips larger than about 5 mm or scratches that go through to the metal, a brush touch-up may not give a satisfactory result. Spray-can paint matched to the colour code can work for larger areas if you can mask carefully and use multiple thin coats. For visible body panels, professional spot repairs from a body shop start at around A$200 to A$400 per panel and give a near-invisible result.
Paint Pens and Sprays
Pre-mixed touch-up paint pens are convenient and produce decent results on small chips. Spray-can touch-up paint is harder to use precisely – good for refinishing larger areas after sanding but overkill for stone chips. Some kits include both a pen for the colour and a separate clear coat pen for sealing.
MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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