So you've finished spraying, laid down your clear, and you're staring at fresh paint that looks good but not quite showroom. That mirror-deep, wet-look shine you see on the top jobs doesn't come straight off the gun. It comes from what's called a cut and polish, also known as colour sanding and buffing. It's the step that takes a paint job from impressive to spectacular.
If the idea of dragging sandpaper across your brand new paint makes you nervous, relax. Everyone flinches the first time. Follow the steps below and you'll get there.
Before You Start: Let It Cure
This is the one rule you cannot skip. Your clear coat needs to be properly cured before you touch it. Cut into it while it's still soft and you'll wreck the finish.
Curing time depends on your clear, your hardener, and the temperature, so don't just watch the clock. Use the fingernail test instead: press your fingernail firmly into an inconspicuous spot, an inside edge or a hidden section of the panel. If it leaves a mark or you can dig in, it isn't cured yet and needs more time. When the surface is hard enough that your nail won't dent it, you're good to start.
Warmer conditions speed curing up and cold slows it right down, so give it longer in cooler weather. When in doubt, wait. Rushing this step is the single most common way beginners ruin an otherwise good job.
What You'll Need
Before you start, get your gear together so you're not running around mid-job:
- Wet/dry sandpaper in a range of grits
- A soft sanding block
- A machine polisher
- Buffing and polishing pads
- Cutting compound and fine polish
- Wax or paint sealant
- Clean microfibre cloths
- A bucket of clean, slightly soapy water
Step 1: Knock Back the Nibs
Once the clear is fully cured, run your eye (and your hand) over the surface. You'll usually feel little bits of dust or dry spray sitting proud of the finish, called nibs. Knock these back gently with a tungsten block or a piece of high-grit paper before you start wet sanding properly. You're just levelling the high spots, not sanding the whole panel yet.
Step 2: Wet Sanding
This is where you flatten the surface and kill the orange peel, that slightly rippled, dimpled texture that comes off the spray gun. Wet sanding levels those ripples out so the clear can be polished to glass.
Here's how it works: you start with a coarser grit to do the levelling, then step up through progressively finer grits. Each finer grit removes the scratches left by the one before it, until the scratches are so fine that polish makes them disappear completely.
Soak your paper first. Let it sit in the soapy water for up to an hour before you start. Wrap it around a soft block, never your bare hand and never a hard block, or you'll dig uneven grooves into the paint.
Sand a test area first. Lay the block flat, slide it left and right a few times, then move down and repeat. Use light, even pressure and change your stroke direction as you go to get a cross-hatch pattern. Let the grit do the work. Pressing hard doesn't sand faster, it just causes damage.
Which Grit Do I Use?
Here's the breakdown for a DIY clear-coat job:
| Grit | What it's for |
|---|---|
| P800 to P1000 | Only if you've got heavy orange peel, runs, or bad texture to level first. Skip this on a decent finish. |
| P1500 | Your normal starting point for wet sanding fresh clear. |
| P2000 | Refines the P1500 scratches. Good enough to polish out with most cutting compounds. |
| P3000 | The finishing grit. Essential on dark colours, where sanding marks show up far more, and worth it on any colour for the ultimate finish. |
Pay attention to your colour. Dark colours (black, dark blue, deep reds) are brutal at showing up fine sanding scratches, so finishing at P3000 matters most on those. Lighter and metallic colours are more forgiving, but P3000 still gives you the cleanest result.
Step 3: Cutting (Machine Buffing)
Once you've wet sanded, the paint will look dull and hazy. That's completely normal. Don't panic, that haze is thousands of tiny sanding scratches, and buffing is what clears them.
First, wash the panel down with clean water and dry it with a lint-free cloth to get rid of all the sanding grit. One bit of leftover grit under your pad will drag a scratch right across your fresh work.
Rotary or DA?
There are plenty of opinions out there on polishers, but here are the basics. There are two main types, and picking the right one matters if you're new to this:
- A rotary polisher spins in one direction and cuts fast. It generates heat quickly, which makes it the easier one to burn through an edge or panel with if you're not experienced. Powerful, but less forgiving.
- A dual-action (DA) polisher wobbles as it spins, which keeps heat down and makes it very hard to do real damage. If this is your first cut and polish, a DA is the safer choice. It's slower, but much more forgiving.
Buffing Technique
Make sure your pad is 100 percent clean and properly attached before you start. Apply your cutting compound evenly to the pad. Don't overload it, too much compound is how you burn paint.
Keep the speed sensible. Around 1800 RPM is a good working range. Use a slow-start tool if you've got one, and never stab the trigger, sudden starts and stops burn paint. Keep the machine moving the whole time so no single spot overheats.
Work in small sections, around 30cm x 30cm. On a foam pad, work the compound in with steady overlapping passes, left to right, then up and down, and repeat the pattern. It usually takes two or three passes to bring the shine up. Once you're happy, drop the revs slightly and do one final light pass.
Golden rule: never buff into an edge. Always buff away from edges. The paint is thinnest on edges and body lines, and that's exactly where beginners burn through to primer. If you do burn through, there's no polishing it out, you're back to re-clearing that panel.
Step 4: Finishing Polish
Cutting compound removes the sanding haze but leaves its own very fine marks. A finishing polish on a soft finishing pad removes those and brings up the deep, wet gloss.
Swap to your finishing pad and finishing polish, keep the pad slightly damp so it doesn't grab, and don't sit on any one spot for more than a second or two. Work it until the polish goes clear and the shine comes up, then wipe clean with a damp microfibre cloth before the polish dries and cakes.
Step 5: Lock In the Shine
Last step. Now that your paint is cut and polished to a mirror, protect it with a wax or sealant. This adds a thin protective layer and a bit of extra depth and gloss on top of all your hard work.
Apply a small amount to each section, let it haze over for a few minutes, then buff it off with a clean microfibre cloth. Stand back, and if you've done it right, you'll be looking at a deep, mirror-like shine that makes all that sanding worth it.
The information on this page is general information only. Always read the product data sheet and safety data sheet before starting any work.