It's a real bummer when you realize you need to get scratches out of plexiglass, especially if it's on a display case, a boat windshield, or a piece of DIY furniture you just finished. Plexiglass—which is basically just a fancy brand name for acrylic—is awesome because it's lightweight and way harder to shatter than glass, but the tradeoff is that it's incredibly easy to scuff. You move one heavy box against it or wipe it with the wrong kind of cloth, and suddenly you're looking at a hazy mess of lines.
The good news is that you don't usually have to throw the whole thing away. Most of the time, those marks are just on the surface, and with a little bit of elbow grease and the right supplies, you can make it look crystal clear again. Here's a rundown on how to handle it without making things worse.
Assessing the damage: The fingernail test
Before you start grabbing tools, you need to figure out what kind of scratch you're dealing with. Not all scratches are created equal, and the approach for a light haze is totally different from a deep gouge.
The easiest way to check is the fingernail test. Gently run your fingernail across the scratch. If your nail slides right over it without catching, it's a surface scratch. These are the easiest to fix and usually only require a bit of polishing. If your nail actually drops into a groove or catches on the edge, you've got a deeper scratch. This is going to require some actual sanding to level out the surface before you can polish it back to a shine.
If the scratch is so deep that it's almost a crack or goes halfway through the material, you might be out of luck. At that point, the structural integrity of the plastic is compromised, and trying to buff it out might just create a weird optical distortion in the plastic that looks worse than the scratch did.
Dealing with light surface scratches
If you've got those fine, wispy scratches that you can only see when the light hits them at a certain angle, you're in luck. You don't need a full-blown workshop to fix these.
The toothpaste trick
Believe it or not, basic white toothpaste is a great mild abrasive. Make sure you aren't using the gel kind or anything with big "whitening beads" that might actually scratch the plastic further.
First, clean the area thoroughly with a damp microfiber cloth to get rid of any dust. If there's grit on the surface when you start rubbing, you're just going to grind that grit into the plexiglass. Once it's clean, dab a small amount of toothpaste onto a soft cotton cloth or a microfiber pad. Rub it into the scratch using small, circular motions for about 30 seconds to a minute.
Wipe it away with a clean, damp cloth to see how it looks. You might need to do this a few times, but for very light scuffs, it works surprisingly well. It's basically a super-fine liquid sandpaper that levels out the edges of the scratch so the light doesn't catch on it anymore.
Using a specialized polishing compound
If toothpaste doesn't quite cut it, you can step up to a dedicated plastic polish like Novus No. 2. These products are specifically engineered to get scratches out of plexiglass without leaving behind a cloudy residue. The process is the same: clean the surface, apply a small amount of the compound, and buff in circles.
The trick here is consistency. Don't press too hard. If you push like you're trying to scrub a stain out of a carpet, you'll generate heat. Heat is the enemy of plexiglass because it can cause the plastic to warp or "smear," leaving you with a permanent blur.
Fixing deeper scratches with sanding
When the fingernail test fails and your nail catches in the groove, it's time to get serious. You're going to have to remove a tiny bit of the surrounding material to bring it down to the level of the bottom of the scratch.
Start with wet sanding
You'll want to get some wet/dry sandpaper. I usually recommend starting with 800 grit if the scratch is noticeable, then moving to 1000, 1500, and finally 2000 or even 3000 grit.
Wait! Before you start, soak the sandpaper in water for about 10 or 15 minutes. You also want to keep a spray bottle of water handy to keep the plexiglass wet while you work. The water acts as a lubricant and keeps the plastic cool.
Start with the 800 grit and sand in small circles over the scratch. Don't just stay on the scratch itself; feather it out into the surrounding area so you don't end up with a "divot" in the plastic. After a minute, the area is going to look "milky" or frosted. Don't panic! This is supposed to happen. You're essentially replacing one big scratch with thousands of microscopic ones.
Progress through the grits
Wipe the area clean and check your progress. If the original deep scratch is gone, move up to the 1000 grit. The goal of each subsequent grit is to remove the scratches left by the previous one. Spend a few minutes with each grit, always keeping the surface wet. By the time you get to 2000 or 3000 grit, that milky cloudiness should start looking more like a light haze.
Bringing back the shine
Once you've finished sanding, the plexiglass won't be clear yet. It'll look better than it did after the 800 grit, but it'll still be dull. This is where the final polishing comes in.
This is the stage where you use a heavy-duty polishing compound (like Novus No. 3 followed by No. 2). If you have a buffing wheel or a drill attachment, this goes a lot faster, but you have to be extremely careful with power tools. If the pad stays in one spot for more than a second or two, the friction will melt the plexiglass.
If you're doing it by hand, use a clean microfiber cloth and some serious muscle. Keep buffing in circles until the haze disappears and the clarity returns. It takes a bit of time, but seeing that clear surface emerge from the cloudiness is honestly pretty satisfying.
What to avoid when cleaning plexiglass
A lot of the time, people end up needing to get scratches out of plexiglass because they tried to clean it with the wrong stuff in the first place. If you want to keep your plastic looking good, there are a few things you should never do.
- No Windex or Ammonia: Most household glass cleaners contain ammonia or alcohol, which can cause "crazing." Crazing is a series of tiny microscopic cracks that make the plastic look permanently cloudy or shattered inside. Once that happens, there's no fixing it.
- No Paper Towels: This is the big one. Paper towels are actually quite abrasive because they're made from wood pulp. They will leave tiny swirl marks all over your plexiglass. Always use a clean microfiber cloth.
- No Dry Wiping: If there's dust on the surface and you wipe it with a dry cloth, you're just dragging those dust particles across the surface like sandpaper. Always use a liquid cleaner or at least a damp cloth.
Knowing when to call it quits
Sometimes, despite your best efforts, the scratch is just too deep or the area is too large to fix by hand. If you're looking at a piece of plexiglass that is covered in "spiderweb" scratches from years of bad cleaning, it might be more cost-effective to just replace the sheet rather than spending six hours sanding and buffing it.
Also, if the scratch is on an optical lens or something where perfect vision is required (like a helmet visor), be careful. Even a well-repaired scratch can leave a slight "lens effect" where the light bends differently through the thinned-out plastic. For safety-critical items, replacement is usually the better bet.
But for your average DIY project or home decor? A little sandpaper and some patience will usually do the trick. Just take it slow, keep things wet, and don't freak out when it looks blurry halfway through the process. It'll clear up!