If you're working on a project that needs sanding, such as auto bodywork or sanding drywall, you may or may not be aware of how wet sanding fits works. Well, what exactly is it, and why do people use it? We're breaking down what this version of sanding is and all the questions you may have about what it is and how to do it.
What is Wet Sanding?
Wet sanding is the process of using an abrasive with water or another liquid to sand down a material. The water or other liquid helps remove any grit particles from the sandpaper left over from dry sanding to ensure a smooth and glossy finish. It's saved for the late stages of sanding, early stages of buffing and polishing, when doing touch-up work, to make minor surface repairs, or removes scratches to paint or other surfaces.
Wetsanding allows you to remove any scratches that dry sandpaper may have caused without removing too much of the underlying material. It can also be a great tool for paint correction to fix any defects or imperfections from an uneven paint job and remove any debris that may have gotten stuck in the paint finish.
Wet vs. Dry Sanding
Both wet and dry sanding help smooth out the surface of an object, but in different ways. You don’t always have to dry sand and wet sand together, but it’s common for some tasks. While many people pair them together, there are some differences between the two.
The obvious difference is that for dry sanding, the sandpaper is completely dry. When it comes to the wet method, you'll lubricate the sandpaper with water or another liquid, oftentimes a detergent.
Dry is going to be more aggressive, especially with lower grit sandpaper. This allows you to shape your workpiece or significantly grind down uneven surfaces to level them out. Wet sand paper is used in a later stage of the process to bring out a shine on the object or to prep for buffing and polishing.
Another significant difference between the two is the application process. When you're dry sanding most surfaces, you'll usually use small circular motions. When doing so, you'll apply pressure to sand down the material to your preference.
When you're sanding wood with wet sandpaper, you'll move in straight lines. To ensure the smoothest finish, you'll alternate the direction of the line each pass. A light hand is utilized here because you don't want to sand away more material.
Unlike regular sandpaper, wet sandpaper avoids loading, which is when the paper gets gummed up with the surface material sanded off. The liquid lubrication and the specific design of the wet paper's abrasive side pushes the debris away instead of sticking to the abrasives.
Common Applications
Without sanding, many of our everyday objects and furniture would be much rougher and duller looking. These are some of the most common applications for this method.
Wet Sanding Wood
More often than not, you'll see people dry sanding wood products to avoid splinters, reshape the surface, or flatten an uneven area on the wood. You'll typically use wet sanding on woodworking projects that you'll find in your homes, such as a table or chair to give the wood a smooth and almost glassy appearance.
Certain wood projects, like wet sanding a guitar, should be done with less water than other jobs. Wood has a habit of absorbing water, and it can leave the wood swollen or warped if you soak it too much. In these instances, it's best to spray just enough water onto the surface and wipe it away once you're done sanding.
Wet Sanding Drywall
A lot of people use wet sandpaper on drywall when prepping an entire room for paint or just repairing a section of drywall. While it does take a bit longer than using dry sandpaper, sanding spackle with a wet sponge noticeably helps eliminate the amount of dust that is normally produced.
There are specific abrasive sponges made for wetsanding drywall, but often a regular sponge can do the trick.
Wet Sanding Metal
Metal is commonly wet sanded to make the surface look flawless. When you do this to metal, it helps remove any minor defects on the material while improving the shine. This can also be beneficial in revamping a dull metal product that has lost its luster from use or age.
When using wet sandpaper on a metal surface you’ll want to pause regularly to reapply water. Reapplying water to the metal or the sandpaper will make sure your product turns out as smooth as possible.
Also check out - How to Wet Sand Metal Surfaces – A Step-by-Step Guide
Wet Sanding a Car
Cars are another very popular object for this method. Many autobody shops will do this to remove deep car scratches. It's also used when painting a car to remove any dust or other particles that may have landed on a fresh coat of paint, and fix other imperfections from a recent paint job like orange peel.
When wetsanding a car, you’ll want to use water with an advanced detergent.
FAQ
If you need help deciding if this sanding method is the correct method for you or what to do before you begin, we can help. Here are the most commonly asked questions regarding how to wetsand.
Is Wet Better Than Dry Sanding?
Both wet and dry sanding have their benefits. Dry is excellent for initially smoothing a material, whereas using a wet sandpaper can drastically improve upon the smoothness while removing scratches. Depending on the type of material you're working with determines which sanding method is better for you.
Dry will do most of the hard work that's usually necessary. Wet will make the surface look and feel professionally made with a cleaner and glossier surface.
The wet sanding process is also most helpful for many interior projects when your goal is to minimize how much of a mess you make. For example, if you're sanding drywall, you can drastically reduce the amount of dust and other particles that can get trapped inside or float through the air throughout your house.
When is Wet Sanding Necessary?
It is necessary when you want the project you're working on to have an ultra glossy finish without skipping any steps. Lots of times you can skip this step, but it's almost always going to be noticeable in the end. You may wind up being upset with your end results and may want to go back to fix the mistake, which will add a lot more time to the process.
It is entirely up to what you are working on and the look you want though. Many people wish to have this type of glossy finish on their car, furniture, or wooden guitars. Wet sanding is likely not necessary if you'd prefer a matte or brushed finish. If you want to have this glossy finish, you'll dry sand first and then wet sand. You can always finish off by buffing and polishing if you want to reach a mirror-like finish.
Can You Use Regular Sandpaper?
You won't want to use regular sandpaper sheets for wet sanding. The abrasive grit on regular sandpaper loads up with the material being sanded. This, plus the grains, will usually cause more scratches on the material. You'll want to use sandpaper that's made specifically for this method.
There is wet dry sandpaper made with silicon carbide abrasives that can be used for both types of sanding, wet or dry. The backing is made out of latex, rather than cloth or paper, to keep it intact throughout the process and help avoid loading.
Can You Wetsand With a Scotch Brite or Scuff Pad?
Yes, you can. Scotch Brite and other scuff pads made of unwoven nylon with embedded abrasive grains are great tools to use wet or dry. Their life span is much longer than traditional wetsand paper, and they come in multiple grit levels to ensure the smoothest possible finish.
What Are the Benefits of Wet Sanding?
One of the main benefits of doing this is reducing the number of scratches on your finished product. Other benefits include a super smooth finish and the ability to remove deep scratches from a variety of materials.
Should You Wet Wood Before Sanding?
You don't technically need to wet the wood before sanding. But, if you want a piece of wood that has an incredibly smooth finish, utilizing a damp surface is your best bet. When wood is damp, you cannot avoid raised grains. You can easily sand these away to get the finish you want, but it might take some patience.
You’ll want to be careful not to get the wood wet again after you’ve finished. If this happens, you’ll have to start the sanding process from the beginning. It’s not a huge problem, but it can be inconvenient.
What Grit Sandpaper Should I Use?
When you're first beginning to wet sand your material, you'll want to start with a grit between 600 and 1,200. Once you choose your starting grit, you'll follow dry sanding standards to increase the by 200 to 500 grits per pass to get the finish you want.
If you dry sanded first and you sanded with a grit of 600, you'll want to start sanding with an 800 grit that is damp, and so forth.
How Long to Wait Before Wet Sanding a Clear Coat?
Once you’ve applied a clear coat to your product, you don’t want to immediately begin sanding. Doing so will ruin your hard work. You'll want to wait at least 24 hours and no more than 48 hours. You want to give it at least 24 to dry and harden fully, but if you wait longer than 48, it might get too difficult to sand.
Will Wet Sanding Remove Paint?
Yes, you can use it to remove paint from most surfaces. It's a favorite among autobody workers and car restoration pros for this purpose.
If you plan to wet sand paint off of your vehicle, be sure to check your local regulations on wastewater pollution. Some states (New York, for example) have regulations about how to dispose of wastewater created by removing this much paint. To minimize wastewater pollution, you can use a spray bottle to apply water instead of having a continuous flow of water and paint dripping from your car.
Does Wet Sanding Remove Deep Scratches?
This is one of the preferred methods for removing deep scratches on most materials. While this process is effective for removing deep scratches, you’ll still need to do so with care. It’s usually best to start with a higher grit than you expect, just to make sure you don’t strip the paint from the surface of the workpiece.
Still have questions?
If you still need some more information about how to wetsand or whether or not wet sanding is right for your next job, feel free to call one of our abrasives experts to help you out.