How to polish gloss paint and remove scratches
Ever wondered how to get that sheen back on your once-sparkly gloss-painted bike? Perhaps a little heel rub or bike lean gone wrong has left a scratch in the surface of your paint?
In many cases, all it takes is a few basic supplies, a little elbow grease, and a bucket of patience. And to show you how, we enlisted Steve Gardner of Velocraft in Melbourne. Formerly known as Bikes by Steve, VeloCraft has quickly become one of the most sought-after bicycle paint shops in Australia. If you’ve ever seen the paint on a Prova or Bastion you’ll understand why.
A quick disclaimer: This is just a quick guide to the process and includes tips used to add a mirror-like shine to gloss painted frames. The same technique and process applies to remove superficial scratches and rub marks. It’s important to note that the instructions in this article do not apply to satin and matte finishes.
What you’ll need
Air or electric-powered tools make quick work of polishing, but it can all be achieved by hand, too. In either case, you’ll want a well-lit area that will show off imperfections.
If polishing by hand:
- 2,000- and 3,000-grit sandpaper
- Microfibre cloths
- Abrasive compound
- Machine polish
If polishing by power:
- 2,000-grit sandpaper
- 3,000-grit sandpaper or 3,000-grit sandpaper disc and air-powered paint buffer
- Paint buffer machine
- Paint cutting pad (VeloCraft uses generic pads from eBay, sold in a bundle pack)
- Paint polishing pad (as above)
- Abrasive compound
- Machine polish
Polishing a frame in three steps
Polishing a freshly painted gloss frame is often done in three stages, with each stage using a progressively finer and smoother abrasive material.
Those with a previously painted frame can likely skip the first step. Likewise, if your paint is in good condition but the finish has gone dull then you may be able to skip the second step, too.
Step one: Removing the dust and peel
Most freshly painted frames will have a small amount of dust or imperfections in the surface. This first step is to use a light abrasive material to remove these imperfections.
Before starting, Gardner will mask off the ending and raised edges of the paint commonly seen around the head tube, cable ports, bottom bracket, dropouts and similar. Doing so protects these delicate areas where it’s possible to accidentally wear through the paint.
Then Gardner uses 2,000-grit sandpaper with water to gently remove any trapped dust or other imperfections. This is then followed by a finer 3,000-grit wet sandpaper to remove the light scratches caused by the 2,000. Both of these are specialty grits – you won’t find them at a hardware store. Simply rub the area gently in a circular motion. Patience is key with all steps.
Once that step is done, wipe the frame with a clean microfibre cloth.
Step two: Cutting compound
This middle stage starts bringing the paint to a polish by gently abrading any peaks and troughs in the paint and creating a smooth finish.
Here Gardner uses the Milwaukee M12 paint buff tool, something he describes as the “Best thing I’ve ever bought”. This is used with a generic and low-cost cutting pad and his preferred paint cutting compound – Farecla G3 Premium. You can achieve the same result with a microfibre cloth, cutting compound, and some serious elbow grease (especially hard work if the paint isn’t fresh, where the surface will have hardened).
Gardner applies a small amount of cutting compound to the pad and then rubs it along the frame surface he’s about to prepare – this reduces the compound splattering.
Gardner moves the tool in a smooth, random motion along the painted surface, noting that spending too long in a single area can create heat which can damage older paints and potentially carbon frames, too. If doing it by hand, do it in a circular motion.
This stage should leave you with a smooth and even finish, but a close look under light will reveal swirl marks from the cutting compound.
Wipe the frame with a clean microfibre cloth.
Step three: Polish
This final stage is much like the previous, but here Gardner moves to a fine polish compound that removes the swirl marks from the paint.
Gardner sticks with his well-loved Milwaukee paint buff tool but swaps to a smoother and softer polishing pad and 3M’s 05996 machine polish (aka swirl remover). That machine polish liquid can be used with a microfibre cloth, too.
The technique is the same as step two, using a smooth random motion across the surface.
Wipe clean and marvel at your own reflection.
The whole process of polishing a frame can take anywhere from an hour to five hours (a show bike is likely to be closer to five hours).
Removing surface scratches
Surface scratches are common on bicycles and can often be found at the chainstays from heel rub, on the top tube from a cleat, or on the head tube from where a little cable rub has occurred. Assuming the scratch is only on the surface then it’s possible to make it disappear.
Removing surface scratches from a gloss paint follows the same process as outlined above, and in many ways, it’s not all that different to the process for polishing raw aluminium and steel. The goal is to remove the scratched layer of paint and effectively make that area progressively smoother until it matches the surrounding paint.
To remove surface scratches you’ll want to remove the bare minimum amount of paint. For this, you’ll skip the wet sanding stage.
Step one: Cutting compound
This is the same as outlined in step two above. You’ll need a cutting compound and a microfibre cloth. Powered tools can also be used.
Here you’ll use a firm pressure and rub the scratched area with a circular motion. Don’t focus solely on the scratch, but rather the surrounding area as you’re effectively trying to smooth off the paint in this area and blend it in.
Repeat until the scratch has faded or ideally is no longer visible. Wipe the area clean. You can call it good here, or move to the polish stage.
Step two: Polish
This stage will remove the swirl marks and bring out a polish from the previous work. Repeat the directions outlined in step three above by using a microfibre cloth and a polish.
Rub the area until the scratch is gone and the surface has a consistent shine to it. The whole process of removing a surface scratch should only take 5-10 minutes.
Don’t forget to marvel at your handywork when you’re done!