Wet sanding is an essential technique for painting, buffing, and waxing. You can use it on many different surfaces to get a smooth, even polish. You can do it on metal, wood, or the hull of your speedboat. But can you sand spray paint? The answer: Absolutely!
Sanding is smoothing out a rough surface, like wood or rusting metal, by scrubbing it vigorously with sandpaper. Wet sanding involves a type of sandpaper that, when coated in water, acts as a powerful abrasive. It is used to create a nice glossy shine and scrape off particularly tough layers of paint.
Wet sanding will scrape off and smooth out the spray paint. However, that is hinged on whether you allow it to dry beforehand. When spray paint is coated with a finisher and given the chance to dry on a surface, it can make the rougher patches of that surface easier to see.
This will benefit you, as it means you can use wet sanding to remove those patches easily. Additionally, it gives the paint a nice, shiny look when finished.
Wet sanding is also uniquely abrasive when compared to its dry counterpart. That will mean two things you’ll need to factor in when using this method. One, it can remove coatings that dry sanding cannot. Two, you need to be very careful while doing it. It is far too easy to accidentally scrub too hard while wet sanding, and leave behind scuff marks that are difficult to remove.
How Long Before You Can Wet Sand Spray Paint?
Okay, so we’ve established that you can wet sand spray paint. But can you do so when it’s wet? In other words, you might be wondering how long to wait before wet sanding spray paint?
There are a few reasons you might want to wait until spray paint has dried before starting to wet sand. On materials like wood, dried spray paint can help highlight the rough patches on the surface, making it easier to determine where to focus your sanding efforts. And in general, dried spray paint is just easier to wet sand than wet spray paint.
So, how long to let spray paint dry before sanding? Ideally, wait 30 minutes for the spray paint to dry. Then, after carefully sanding the surface, apply another coat of paint.
Wet sanding between coats of spray paint is an excellent way to smooth out your surface while also ensuring your sanding hasn't made your coat uneven by scraping off too much paint. Once everything looks nice and even, you can put on a clear coat to ensure it stays that way.
How to Wet Sand Spray Paint Step By Step
Wet sanding requires a waterproof sandpaper designed to become more abrasive when wet. A sanding block or a sander is needed to hold it, plus some water to soak the paper in.
Different sandpapers have different grain sizes. Finer grains mean a more effective abrasive. The closer you get to the finishing coat, the finer the grain size you should be using, and the more careful you need to be with your sanding technique.
For this reason, it’s good practice to have two or three types of wet sandpaper on hand for your project. Of course, the specific grain sizes you choose to use will depend on the material you're painting, so research which papers work best for you.
There are several steps you will need to take for wet sanding spray paint.
First, soak the sandpaper in the water while your first coat of spray paint dries. The water on the sandpaper will unstick stubborn particles, making it easier for the paper to do its job.
Then, using a sander or sand block, carefully sand the spray paint to eliminate the most prominent rough spots. Remember, you’re not trying to smooth it out completely, at least not yet. For now, you just want a general sanding of the surface. Although it does depend on the surface material, you probably want to use 200 grit sandpaper for this stage.
Apply a finisher to the paint, and leave it to dry overnight. After 24 hours, the spray paint will have revealed the uneven portions of the surface, which your first round of sanding might have missed.
Soak your sandpaper again, preferably one of finer grain size, and start another round of wet sanding.
Usually, two or three coats of spray paint are recommended before you start on the clear coat. You should sand in between each coat you apply to keep the paint nice and even across the surface you're working on.
The final round of sanding happens right before you apply the clear coat and uses the finest sandpaper. Once again, it depends on the surface, but sandpaper for this final step tends to be in the 1000-2000 grit range. This is where you need to be extra careful, as such an effective abrasive can easily strip away the layers of paint you’ve spent so long working on!
Finally, apply the clear coat, and admire the results of your hard work!
Tips & Tricks
Always remember to check the type of sandpaper you’re buying. If it's not advertised as wet sandpaper, you probably shouldn't use it for wet sanding. You can also use the internet to determine which grain size works best for your project. Remember: the finer the grain, the more gentle you need to be while sanding.
Wet sanding, combined with any form of paint, inevitably leads to droplets of liquid paint dripping onto the ground. So if you’re sanding spray paint, be sure to do it outside or you may end up with drips to fix later.
When spraying with single-stage paint or paint which does not require a clear coat, you should check with the manufacturer before deciding to wet sand. Because the clear coat is mixed directly into the paint, sanding could strip away the much-needed UV protection that the clear coat usually provides.
Frequently Asked Wet Sanding Spray Paint Questions
Can you wet sand over a clear coat?
Yes, as long as you are careful and apply another clear coat afterward. Clear coats protect your paint against the elements and ensure that it takes longer to fade away. The uneven clear coating can result in unsightly splotches as time goes on.
Can you wet sand with a palm sander?
Generally, the answer is yes, although you should check with the sander’s manufacturer to be sure. Mixing water with electrical equipment isn’t always a good idea, especially if the equipment wasn’t meant to be waterproof.
So, can you sand spray paint? Wet sanding is a great way to even out the surface of your project, and it provides a strikingly glossy visual once the process is complete. And if you’re being careful, you can apply this technique to spray paint as well.