Wet sanding is an effective way to wash away grit particles and prevent them from accumulating on the sandpaper. Hand wet sanding can be tedious due to the need to dip the sandpaper in water and wring it out regularly. Although an orbital sander can make the process easier and more consistent, is it safe for your wood?
You can wet sand with an orbital sander but must be cautious not to hurt yourself or damage your surfaces or tools. Orbital sanders rotate quickly, making them very aggressive in their sanding. Therefore, the aggressiveness can damage your surfaces if the device is used for wet sanding without care.
In the rest of this article, I’ll discuss how to use an orbital sander for wet sanding. I’ll also discuss the differences between dry sanding and wet sanding, including when the latter is preferred. Let’s get started!
How To Wet Sand With an Orbital Sander
Wet sanding is your go-to option if you want a smooth, scratch-free surface and for finishing softwoods like pine and cedar. However, wet sanding a larger surface by hand is tedious, making it necessary to employ an orbital sander.
Since an orbital sander is not meant for wet sanding, you must take precautions when using it for this role.
The following are some guidelines on how to wet sand with an orbital sander:
Be Mindful of Electricity
Wet sanding involves adding a liquid lubricant like water or a detergent on the surface. The liquid lubricant can be a threat since orbital sanders use electricity. The free ions in water or detergent create a conductive path for electricity and can result in electrocution.
If you must wet sand with an orbital sander, it’s advisable to prevent the water from coming into contact with the motor. Moreover, you must ensure the orbital sander’s wires and cords are not damaged and are properly insulated.
Sanders with double insulation, such as those with a rubberized covering, are best for wet sanding. A good example is the BO5041 5” Random Makita Orbital Sander, available on Amazon. Not only is the grip for this sander rubberized, it is also ergonomic, ensuring you’ll be as comfortable as possible while working on your project.
Use the Right Sandpaper Grit
When wet sanding with an orbital sander, you must use a grit lower than what you would for dry sanding since liquid lubricants like water can clog up higher grits quickly.
Additionally, using too high-grit sandpaper on wet wood can easily damage it, resulting in an uneven surface.
It’s best to start with grit between 600 and 1,200 for wet sanding before gradually progressing to higher grits.
Apply Minimum Sanding Pressure
As mentioned earlier, orbital sanders have high revolutions per minute. Some can go as high as 12,000 rpm. Such high revolutions make their sending process more aggressive and can damage the surface if too much pressure is applied.
When wet sanding with an orbital sander, it’s best to apply little to no pressure and let the tool do most of the work. This way, you can avoid damaging your surfaces or creating uneven areas on them.
You must also be extra careful when sanding the edges as surface tension in these areas is weaker, making them more prone to damage.
Choose the Right Liquid Lubricant
As stated earlier, water is a common choice for wet sanding. However, it is not always the best option as it can easily create unwanted marks on softwood surfaces.
In cases where soft surfaces are involved, using a lubricant specifically designed for wet sanding gives better results. One example is WD-40, which adds additional protection to wood surfaces while promoting smooth sanding.
Use Wet Sandpaper
Wet sanding is specifically meant to bring out a shine on the object. However, regular sandpaper is not perfect for this job. Instead of polishing the surfaces, regular sandpaper will likely disintegrate when exposed to moisture.
Wet sandpapers are the best option for the job since they are designed to withstand moisture and promote a smooth, shiny finish on surfaces. They also come in various grits, allowing you to choose the best option for your desired polish level.
Protect the Moving Parts from Sizing or Rusting
Water exposes the orbital sander’s moving parts to moisture, making them susceptible to rusting and seizing. When this happens, you’ll have to replace the plate or the flat surface where sandpaper is attached.
An orbital sander with a sealed bearing is the best option for wet sanding. Sealing the bearings prevents water from getting in and causing rust or size build-up.
Alternatively, you can water the surface you’re wet sanding instead of the orbital sander’s pad. This method reduces the sander’s exposure to moisture, minimizing the risk of rust and size build-up.
Buff up the Surface
The final step in wet sanding is buffing the surface to bring out a smooth, shiny finish. You can use a soft cloth or buffing pad for this role.
Finish by applying wood polish or wax on the surface to maximize the results. This added step helps protect and preserve the wood for years to come.
Dry Sanding vs. Wet Sanding
Dry and wet sanding are common terms in the woodworking world. Dry sanding is the traditional method of sanding wood surfaces using only dry sandpaper and a sander. In contrast, wet sanding uses a liquid lubricant to help smoothen out the surface and prevent grit accumulation.
Each method has benefits, as discussed below:
Benefits of Dry Sanding
- It smoothes out significant blemishes on the surface.
- It slims down on uneven corners.
- It eliminates curves, errors, and major bumps.
- It’s more convenient since it doesn’t require additional materials like water or lubricant.
Benefits of Wet Sanding
- It eliminates minor surface issues, resulting in a smooth, polished finish.
- It prevents the accumulation of wood particles and grit on the sandpaper, preventing scratches that can ruin the finish.
- It reduces friction and heat build-up during sanding, protecting the surface from damage.
- It’s a suitable option for polishing surfaces like metal or plastic.
The table below summarizes the differences between dry and wet sanding:
| Dry Sanding | Wet Sanding |
| No lubricant is needed | Uses water as the main lubricant |
| Removes more material | Removes less material |
| Requires lower grit sandpaper | Requires high grit sandpaper |
| Creates smooth finishes | Creates super smooth finishes |
| Takes less time | It’s time-consuming |
| Causes a significant mess | Has less mess |
Table 1: Differences between dry and wet sanding
While both methods have their benefits, it’s important to note that dry sanding is often used as a base for wet sanding. Dry sanding takes care of the major blemishes on the surface, while wet sanding smoothes out minor imperfections, bringing out a shine.
When To Wet Sand
Wet sanding is suitable for finishing softwood surfaces, particularly those that produce burn marks when dry sanded. It’s also best for obtaining a fine and smooth finish on wood or bodywork surfaces.
However, wet sanding may not be necessary if you’re working with hardwoods like oak or walnut since they typically don’t produce burn marks or require a fine finish.
It’s worth noting that wet sanding bare wood doesn’t make sense for the following reasons:
- It’s not yet time for a super smooth finish: Since fine dust clogs wood pores and prevents proper finish adhesion, it’s best to wait until after applying a finish before wet sanding.
- Wet wood swells and can damage the surface: Wet sanding on bare wood will only cause swelling and potential damage to the surface.
- Wet sanding is intended to remove manufacturing flaws and marks: Sanding bare wood won’t remove them since the surface hasn’t been worked on yet.
The Downsides of Using an Orbital Sander for Wet Sanding
An orbital sander is not the best tool for wet sanding due to the following reasons:
- It’s aggressive: Wet sanding is meant to create finer and smoother finishes. However, the orbital sander’s circular motions are more aggressive and can lead to scratches on the surface if not used cautiously.
- It doesn’t have enough control: Wet sanding requires slow and controlled movements, which may be difficult to achieve with an orbital sander since the tool operates based on its set RPM.
- It’s challenges to use in corners and tight places: The orbital sander’s round pad shape and rotating motions make it difficult to maneuver in tight spaces or corners, where wet sanding is often necessary.
- The risk of electrocution: Using an orbital sander in wet conditions can increase the risk of electrocution. Therefore, apart from sanding, you’re tasked to ensure the water doesn’t come in contact with electricity.
- Costly repairs: The orbital sander’s parts risk rusting or seizing up when you use it for wet sanding. When this happens, you’ll need to replace parts like the bearings, adding unnecessary costs.
Ultimately, it’s best to use a hand block sander for wet sanding as it allows for more control and precision in movements. However, if you choose to use an orbital sander for wet sanding, make sure to go slow and gently guide the tool on the surface.
Using a Pneumatic Air Sander for Wet Sanding
Along with a hand block sander, the pneumatic air sander is the best tool for wet sanding. If you want to wet sand a larger surface which can be tedious to do manually, the pneumatic air sander can help you speed up the process.
Unlike an orbital sander, a pneumatic air sander doesn’t use electricity directly. Electricity only comes into play when re-pressurizing the air tank in the compressor. This makes the tool appropriate for wet sanding as it minimizes the risk of electrocution.
The main downside of a pneumatic air sander is that you need an air compressor to operate it, which can be a costly investment. However, the investment is worth it for those wet sanding large surfaces and projects efficiency.
Like an orbital sander, make sure to go slow and gently guide the sander on the surface to avoid scratches. Also, be wary of water getting into contact with electricity by properly sealing off all openings in the air compressor and hose.
Safety Considerations When Wet Sanding
Wet sanding can be a messy and potentially dangerous process. Therefore, it’s essential to take the following precautions to avoid injury or damage:
- Wear safety gear: This includes goggles, masks, and gloves to protect yourself from wood dust and possible chemical exposure from sanding agents.
- Be cautious of electricity: Avoid getting water on electrical tools or power sources to prevent electrocution.
- Secure the surface: Make sure the surface you’re sanding is securely in place since the lubricant makes wood slippery. You can use a roll or nonslip shelf liner to secure the wood.
- Clean up immediately: It’s advisable to clean up any excess water or sanding agent on the surface before it has a chance to dry and potentially damage the sanded surface.
Conclusion
Although you can wet sand with an orbital sander, it’s necessary to take prior precautions for safety. You should ensure the motor and wires don’t come in contact with water to prevent electrocution. Moreover, it’s advisable to apply the lubricant on the sanding surface instead of the orbital sander to avoid corrosion.