Usually, the word "sanding" is used to refer to dry sanding, but there's another technique called wet sanding.
Both techniques remove surface material, but there are crucial differences.
The main difference between wet and dry sanding is that wet sanding uses a lubricant, like water, along with the abrasive. As a result, it is more time-consuming but results in fewer scratches and a smoother finish. In contrast, dry sanding is faster and preferred for removing surface material quickly.
This article compares the wet and dry sanding techniques in detail to help you choose the best option for your project and also provides a clear step-by-step guide for both.
Difference between Wet Sanding and Dry Sanding
|Factor||Wet sanding||Dry Sanding|
|Type of sandpaper||Specifically designed, finer grit||Regular, coarse grit|
|Sanding technique||Circular movements||Straight-line movements|
|Application||Furniture, auto-body primer, tiles, metals||Drywalls, wood, latex-based primers|
When wet sanding, use a lubricant such as water mixed with detergent or dish soap.
This will help reduce friction and heat, minimizing the chances of leaving deep abrasions on the surface.
In contrast, when dry sanding, you don't use any lubricant, which may cause noticeable marks on the surface due to the lack of moisture.
Dry sanding removes more material than wet sanding. It can quickly smooth out rough surfaces.
However, using lubricant during wet sanding helps to reduce the amount of material taken off.
This makes wet sanding better for projects that require careful and gentle sanding. You can use it for a smoother and more even finish.
Type of Sandpaper
When wet sanding, you need to use sandpaper with a finer grit and a special design for use with a liquid lubricant.
The lubrication and specialized design of the abrasive side of the sandpaper helps to keep dirt and debris away, which is especially beneficial when sanding materials that are light or dark in color.
For dry sanding, you need to use sandpaper with a coarser grit. However, this type of sandpaper is not as long-lasting since it has a harsher nature.
Regarding techniques, dry sanding requires you to make circular motions with moderate pressure for an even surface.
On the other hand, wet sanding needs you to use a straight-line motion, alternating directions with each pass to remove any previous scratches.
Furthermore, wet sanding needs less pressure than dry sanding as the objective is to remove surface scratches and not much material.
Wet and dry sanding is equally helpful, and you can use either depending on the project and what you want to achieve.
For example, you can use dry sanding with power tools if working on a large wooden surface, such as a timber floor or a wall.
For more delicate tasks such as polishing and painting, it's best to use hand-held wet sanding.
Dry sanding is the better option for drywalls as they cover larger surfaces.
Wet sanding can achieve greater smoothness and avoid dust formation, although it will require more effort and investment.
Dry sanding is common for removing splinters, shaping surfaces, and evening out non-uniform areas on wooden products.
On the other hand, wet sanding is often used to achieve a glossy finish for woodworking projects like furniture.
Be careful when wet sanding wood as it tends to absorb water which can cause swelling or warping.
You should use minimal water for delicate wood projects like a guitar by spraying it onto the surface and then wiping it away after sanding.
This will help prevent the wood from becoming over-saturated and keeps its shape.
For latex-based primers, you don't need to wet sand as the final coat of paint will cover any surface imperfections.
However, for auto-body primers, it's important that you wet sand to ensure a smooth surface.
Wet sanding is the best way to achieve a smooth finish if you want to paint masonry, porcelain, or ceramic surfaces such as tiles.
Wet sanding removes any small imperfections and produces a professional-looking, polished surface.
Wet sanding is an effective way to remove minor imperfections and bring back the original shine of metal surfaces.
This method is also helpful in restoring the luster of metal products that have lost their shine over time.
To ensure the best possible results, you must frequently apply water to the metal and sandpaper during the sanding process.
Doing this will help create a consistent and smooth result.
Vehicle Body Parts
Wet sanding is an excellent method to remove deep scratches on a vehicle's body. The lubrication prevents the sandpaper from clogging with paint, allowing a more even sanding process.
You can also use wet sanding to remove particles or dust that may have landed on a new coat of paint and correct imperfections like orange peel from a recent paint job.
For best results, use water mixed with a specialized car detergent when wet sanding a car. This will help ensure you get the best results from your sanding project.
Pros and Cons of Wet Sanding
|Very smooth and polished finish||Takes more time than dry sanding|
|Minimal dust formation||Requires manual sanding tools|
|Can be used to remove imperfections||Can be difficult to assess sanding progress|
|Requires frequent rinsing and drying during sanding|
|Not suitable for creating rough textures on surfaces|
Pros and Cons of Dry Sanding
|Faster than wet sanding||Generates a lot of dust|
|Employs power tools for efficient sanding||Can create scratches and swirl marks on surfaces|
|More visible and easier to assess progress||Can damage delicate surfaces|
|Suitable for creating rough textures on surfaces||More difficult to produce a polished finish|
|Not ideal for surfaces that require a smooth finish|
Wet and dry sanding have distinct advantages and disadvantages, making them better for different tasks.
Therefore, it's essential to think about the benefits and drawbacks of each, in addition to your end goal.
You should evaluate which method is the most suitable for your purpose to get the best results.
Wet sanding is the best choice for achieving a smooth and polished finish with minimal risk of scratches and blemishes.
It effectively removes the haze or swirl marks that can sometimes be produced from dry sanding.
Additionally, it can be used to make wooden surfaces even after applying a layer of polyurethane or sealant and to remove minor surface imperfections.
In contrast, dry sanding helps create a rougher texture to improve the adhesion of finishes. You can use this method if a smooth finish is not required.
When wet sanding, you must rinse the sandpaper continually, the surface you're sanding, and your hands with water to ensure the surface remains moist and avoid contamination.
This process takes longer than dry sanding, so you should factor this into your plans.
Keep some towels handy, so you can quickly dry off any excess water and avoid further mess.
Wet sanding is more effective than dry sanding at reducing dust.
Professional interior painters often use wet sanding before painting as the moist sanding dust helps the paint to be applied more evenly and prevents it from becoming contaminated.
However, dry sanding generates a lot of dust that can harm your respiratory health and be difficult to clean up, especially in hard-to-reach places.
You should consider both methods' potential risks and rewards before deciding which is best for you.
Wet sanding can be difficult to tell if you've sanded away too much of the surface. To prevent this, periodically wipe the surface to get an accurate assessment.
On the other hand, dry sanding is more visible and easier when using the proper technique.
Wet sanding the right way - The Process
1. Clean the surface
Before you begin sanding, clean the surface thoroughly to ensure proper adhesion of sandpaper. You may need a solvent to remove grease or oil.
2. Choose the Right Sandpaper
You can use wet-dry sandpaper, but for best results, use sandpaper specifically designed for wet sanding.
Start with a low grit sandpaper, usually 400 or 800, and gradually work to a higher grit.
3. Prepare the Lubricant
Mix water and a few drops of detergent or dish soap in a medium-sized container.
The addition of soap enhances the water's slipperiness and reduces friction, which is ideal for wet sanding.
If you're working with wood, you can use mineral spirits as an alternative to water.
4. Start Sanding
Dip your sandpaper in the water mixture, and wrap it around a wooden block. Sand the surface in straight lines and alternate the direction in each pass.
Apply gentle pressure to avoid any damage to the surface. As the sandpaper dries out, dip it back in the water mixture. Rinse the surface occasionally to inspect your work.
5. Repeat the Process
Repeat the process progressively with higher grit sandpaper (800, 1500, and so) until you reach the desired level of smoothness.
You will usually see the desired results around the 2000-grit sandpaper.
Take regular breaks to avoid fatigue and ensure a consistent sanding pattern.
6. Final inspection and Buffing
After sanding with the finest grit, rinse and dry the surface using a clean, lint-free cloth. Inspect the surface for any imperfections and sand again if necessary.
Finally, use wax and a soft rag to buff the surface to a shiny and flawless finish.
Dry sanding the right way - The Process
1. Clean the surface
Start by cleaning the surface to remove dirt, oil, grease, and other debris that may obstruct sanding.
2. Ensure safety
Wear protective gear like a dust mask and goggles to avoid inhaling dust or getting debris in your eyes.
3. Choose the Right Sandpaper
Start with the lowest-grit sandpaper and sand the material's surface toward its grain.
To make the task easier and quicker, you can use an orbital sander if sanding over an extensive, flat surface.
Alternatively, you can use a wooden block to wrap the sandpaper around if you're sanding by hand.
Always keep the sandpaper flat when sanding and only apply light to moderate pressures.
Avoid lingering in the same spot, and make sure to sand in the direction of the grain to avoid scratches.
If it is difficult to identify the grain direction, look for the lines that run along the surface and sand in the same direction as them.
Once you have finished sanding, check for any visible dents or marks and continue sanding until you are satisfied with the results.
4. Clean the dust
It's important to clean the surface of dust and debris before sanding with the next grit sandpaper.
Otherwise, the debris can get stuck between the sandpaper and the material, causing deep scratches that are hard to remove.
You can use a shop vac, a clean cloth, or compressed air to clean it.
5. Repeat the Process
Repeat the sanding and cleaning step with each of the next grit sandpapers, usually 60, 80, 120, and 180. Check the surface regularly to make sure you've achieved the desired level.
This is important because you won't be able to undo any material that you've sanded away.
I suggest stopping at 180 grit if you’re working with wood because sanding past this grit may close the material's pores, making it hard for stains to penetrate.
6. Final cleaning
To finish up, clean the surface to get rid of any residue. You can use a damp cloth or a vacuum cleaner to remove dust or debris.
Wet and dry sanding can remove rough spots and smoothen surfaces.
You need an abrasive and a lubricant for wet sanding, usually water. It is excellent for delicate surfaces that need gentle sanding or a smoother finish.
While dry sanding requires you to use coarse-grit sandpaper and progress to finer ones, it is best for hard and durable surfaces or when you need rough and quick sanding.
You should begin with dry sanding and use wet sanding for the final touches.
Always wear a dust mask and safety goggles to protect your respiratory system and eyes, especially when dry sanding.
Frequently Asked Questions
Can I use dry sanding to remove paint or varnish?
You can use dry sanding to remove paint or varnish, especially on enduring surfaces. Start with coarser grit sandpaper to effectively remove the top layer, and then use finer grits for a smoother finish.
Which method is preferable for sanding a clear coat?
Wet sanding o a clear coat is preferable, as dry sanding can easily cause damage and leave you with a dull finish. Use finer-grit sandpaper, such as 800-1000, and apply light pressure evenly to avoid uneven surfaces.
Why is my orbital sander leaving swirl marks?
Swirl marks can be caused by several things when using an orbital sander. These include incorrect sanding technique, clogging, poor-quality sandpaper, and a malfunctioning sander. Make sure to take extra care to avoid these problems when sanding.