How to Sand Epoxy Resin (Wet & Dry Sanding)

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Sanding epoxy resin is usually advised to achieve a perfect surface. However, the process isn’t as easy as it sounds.

For starters, epoxy resin is usually very hard after it has cured and this makes sanding very difficult. There are several tips and instructions to follow while sanding epoxy resin.

In this post, you will learn all there is to know about how to sand epoxy resin as well as pro tips to make this difficult task seem like child’s play. So, let’s get on with it.

How to Wet-Sand Epoxy Resin?

To wet-sand epoxy resin, you need the following tools.

  • Waterproof sandpaper: Waterproof sandpaper comes in grit sizes from 60 to 1000 grit. It is always advised to start with a higher grit like 120-grit for epoxy resin. This is because waterproof sandpaper of less than 120-grit can cause scratches and dents on the epoxy which will be very difficult to conceal after.

Another alternative to waterproof sandpaper is a sanding pad. Sanding pads will work well on epoxy resin because they have increased flexibility for curves and edges. Waterproof sandpaper on the other hand isn’t too flexible so sanding edges with it will be difficult. Sanding pads can also be used with water so, they are great for wet-sanding.

  • A pair of gloves
  • Breathing protection: Though wet-sanding doesn’t produce a lot of dust, you should still protect your lungs.
  • A block or piece of wood to wrap the sandpaper around: Wet-sanding is usually done manually or by hand. This is because you need water for wet-sanding and using an electric sander will put you at risk of electrocution. So you shouldn’t use a sander for this method.
  • Water: Of course, you need water for wet-sanding.
  • Clean rags and a soft brush

To wet-sand epoxy resin,

1. Clean the Surface

Put on your safety gear. Your safety gear includes your pair of gloves, breathing protection, a pair of goggles if needed, and every other thing that protects you from harm and injuries while sanding.

Before you sand, you need to ensure that the surface is free from any debris. If the surface is dirty, then the result after sanding will be poor.

Leaving the debris on the surface before you sand can also result in injuries and bruises since you will be sanding by hand. Use a clean rag or a soft brush to clean the surface.

2. Get Water Ready for Sanding

You need to apply water to the surface before and while sanding. You can either get a bowl or bucket of water readily available or you can put water in a spray bottle.

Just pick the method that works best for you. Don’t use hot water on epoxy as the heat can cause the epoxy to dissolve and become very messy. Use cold or warm water to wet-sand epoxy resin.

3. Wrap the Sandpaper Around a Block if Needed

Wet-sanding is usually done by hand but that can prove tough for most people because the epoxy resin is usually hard.

Professionals advise wrapping the sandpaper around a hard rubber sanding block to sand epoxy resin. You should wrap the sandpaper in a way that proves convenient for you.

You should also take note of the scope of the surface to be sanded so you can wrap the sandpaper in a way that will make sanding easier.

If you notice that the surface to be sanded has a lot of curves, you should go for a sanding pad. Waterproof sandpaper is usually too rigid to be bent to sand curved surfaces.

Sanding pads on the other hand are more flexible. As an alternative to wrapping the sandpaper around a block or a piece of wood, you can just sand with the sandpaper directly if that will be more convenient for you.

4. Sand the Epoxy Resin

After you have prepped the surface and you have the sandpaper ready, you can go ahead to wet-sand the epoxy resin. Epoxy resins are usually not rough so you shouldn’t need aggressive or coarse sandpaper. So what sandpaper should you use?

You should start sanding with medium-grit sandpaper like the 120-grit sandpaper and gradually work your way up to fine-grit sandpaper like the 240-grit or 320-grit sandpaper for finishing.

However, if you notice that the epoxy resin has a lot of irregularities, you can start with the 60-grit or 80-grit sandpaper. If you will be using coarse sandpaper, you should exercise extreme caution because the wrong stroke or motion can ruin the epoxy.

5. Spray Water on the Epoxy Resin Surface

To sand, spray water on the surface from your spray bottle. If you don’t have a spray bottle, you can pour a bit of water on the surface with a bowl or simply dip the sandpaper in a bucket of water and sand with that.

The water is used as a lubricant so the sandpaper can move easily on the epoxy resin without any hindrance. You are not trying to soak the epoxy resin so do not add too much water or you will ruin your work.

After you add water, rub the abrasive side of the sandpaper against the surface of the epoxy resin in a circular motion. You should repeat this process a few times.

While sanding, you should take note of where you have sanded and where you haven’t, especially if you are working on a large surface. This will prevent you from over-sanding. After sanding with coarse sandpaper or medium-grit sandpaper, you should finish the surface with a fine-grit sandpaper.

5. Clean the Surface

After sanding for a while, clean the surface with a clean rag to inspect the surface. This will be even easier since you are wet-sanding.

Wet-sanding makes it easy to see the results after sanding. If you notice you have achieved the level of smoothness you are going for, you should stop sanding. If you aren’t pleased, you can continue sanding.

When you are done sanding, you should clean the surface again with a damp rag and then leave it to dry. It is always advised to remove any leftover debris or sand from the surface because it will be tougher to do so when the epoxy resin dries.

When the epoxy resin is dry, you can go ahead with your task. That’s how to wet-sand epoxy resin. Now, let’s check out dry-sanding.

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How to Dry-Sand Epoxy Resin?

Learning how to dry-sand epoxy resin is hard, there are a lot of steps included. To make things easier, we have made a 6 step guide that will teach you all you need to know about dry-sanding epoxy resin.

To dry-sand epoxy resin, you will need the following tools.

  • Sandpaper: You don’t need waterproof sandpaper since you wouldn’t be using water. For dry-sanding, you should get coarse, medium,-grit, and fine-grit sandpaper. Also, ensure you get quality sandpaper because dry-sanding renders sandpaper dull quickly.
  • A sander: For dry-sanding, this is non-negotiable. Sanding epoxy resin is usually difficult and it’s not a task I’ll advise you to take on by hand. Since you are not using water, you can get an electric sander or just go for a battery-powered sander.
  • Breathing protection: Dry-sanding will produce a lot of dust and possibly, chemical particles. You will need a high-quality grade face mask to protect your lungs. Do not take any chances with this.
  • A pair of gloves
  • A pair of goggles: To prevent dust from getting in your eyes.
  • Clean rags

To dry-sand epoxy,

1. Prepare the Surface

Before you can go ahead to sand, you should follow the same preparatory steps as discussed above for wet-sanding. This includes cleaning the surface to be sanded and putting on your safety gear. Remember dry-sanding produces a lot of dust to protect yourself.

2. Provide a Well Ventilated Space

Before you dry-sand the epoxy resin, you should get a well-ventilated space for the work. If you can, move the epoxy resin surface outdoors.

This will give you adequate floor space to work with. Also, you wouldn’t have to worry about inhaling the toxic dust as much. If you can’t move the epoxy resin surface outdoors, ensure all the windows and doors are wide open before you begin sanding.

3. Attach the Right Sandpaper

Since you will be using a sander, you need to attach the right sandpaper to the bottom of the sander. For a very rough epoxy resin, you should start with coarse sandpaper like the 80-grit sandpaper on the surface. Most epoxy resin surfaces will require you to start with 120-grit sandpaper or 150-grit sandpaper.

The instructions to attach the sandpaper are usually indicated on the sandpaper and the sander. Most Sanders use a clamp to hold the sandpaper. The clamp can be released by pulling a lever that is usually located at the back and by the side of the sander.

4. Power the Sander

After attaching the right sandpaper, you should power the sander and switch it on. If the sander is an electric model, you should plug-in the cord. If it’s a battery-powered model, you should slot in the battery.

Related Read — Best Combination Sanders

5. Sand the Epoxy Resin

After attaching the right sandpaper and powering the sander, you can go ahead to sand. Place the bottom of the sander on the surface to be sanded and pull the trigger.

You should start slow so you can keep track of your work. Sanders vibrate a lot while being used, so hold the sander firmly so it doesn’t ruin your work. Do not place too much weight on the sander or you will over-sand the area.

Dry-sanding will render the sandpaper dull quickly, so you should get a replacement nearby. If you notice the sandpaper isn’t doing a good job anymore, you should replace the sandpaper with a new one. Finish the sanded area with 240-grit sandpaper or 320-grit sandpaper.

Depending on the type of epoxy resin you are working on and the type of finish you are aiming for, you might still need to go for finer sandpaper. Sandpaper for epoxy resin can go over 400-grit so if you need very fine sandpaper, you can use that.

6. Dust or Clean the Surface

Since dry-sanding will spew a lot of dust around, you should use a clean rag or a soft brush to clean the sanded surface and to get rid of any residue. After doing that, you can go ahead to finish the surface. That’s how to dry-sand epoxy resin. Simple right? I’m sure it is.

Now you know how to sand your epoxy resin. However, which of the aforementioned methods is better? Should you dry-sand or wet-sand your epoxy resin? Keep reading to find out.

Should You Wet- Sand or Dry-Sand Epoxy Resin?

When it comes to sanding epoxy resin, you should wet-sand rather than dry-sand. Though both methods will work fine if all instructions are followed, the result you will get with dry-sanding cannot be compared with that of wet-sanding.

Asides from the result, the entire process of sanding epoxy resin is very much easier with wet-sanding than dry-sanding. By adding water to the surface before sanding, you will experience reduced levels of dust being spewed around the workspace.

Dry-sanding or sanding without moisture produces a lot of dust and you shouldn’t forget that epoxy resins are made from different chemicals too so it wouldn’t be just dust that would be spewed around. Chemical particles as well will be spewed in the air as you dry-sand and many of these chemicals can be hazardous to your respiratory system if inhaled.

What’s the Difference Between Wet Sanding and Dry Sanding Epoxy Resin?

Wet-sanding involves spraying water on the surface to be sanded and using waterproof sandpaper to sand afterward. Dry-sanding on the other hand as you have guessed doesn’t involve using water or waterproof sandpaper.

You just have to get your hands on the required sandpaper and sand with that.

Is Wet-sanding Epoxy Easier?

Wet-sanding is relatively easier, quicker, and cost-effective. The sandpaper used for epoxy resin is usually of very high grit which means a higher cost.

If you dry-sand, the sandpaper will get dull quickly because of the hard nature of the epoxy resin. This means you will need to occasionally replace the sandpaper (which again, is usually more expensive than regular sandpaper).

Related Read — How to Sand A Deck?

When Should You Dry-sand Epoxy Instead of Wet-sand?

Though dry-sanding epoxy isn’t usually recommended, there are instances where professionals will advise you to do so such as when working with epoxy resin that has been applied or combined with moisture-sensitive materials like wood.

Wet-sanding epoxy resin used with wood, especially light wood isn’t usually recommended because wood tends to absorb moisture quickly and this can affect the condition of the finish.

So when working with epoxy resin combined or applied on wood and other moisture-sensitive materials, dry-sanding will be your best bet. As a pro tip, if you will dry-sand epoxy or any material at all, you should ensure you are putting on very good breathing protection.

 Tips to Follow While Sanding Epoxy Resin

Ensure the Epoxy Resin Is Fully Cured (Dry) Before Sanding

Sanding wet epoxy resin or epoxy resin that hasn’t fully cured can be very dangerous to your health. This is because epoxy resins are made from different chemicals and if you sand the epoxy resin before it fully cures, the chemical particles will be released into the air and you can inhale them.

Do Not Press on the Sander

If you are dry-sanding, do not press on the sander. Most people press on the sander so it doesn’t vibrate. This will only ruin your finish.

You are to hold the sander firmly while sanding not press it down on the surface. You should also pause regularly while sanding to inspect the surface so you don’t over-sand.

Related Read — Best Straight Sanders

Do Not Use Lower-grit Sandpaper if You Have Moved to a Higher-grit

For instance, if you have sanded with 150-grit sandpaper and you are now using a 240-grit, do not go back to the 150-grit.

Using lower-grit sandpaper will only result in a very uneven and poor finish. So ensure you are done with grit before you move to a higher grit.

So there you have it. If you have any questions or comments about how to sand epoxy resin, please leave a comment down below. Have a great sanding experience.

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