Creating a smooth, sanded wood surface makes all the difference for your wooden project’s beautiful finish. Let’s talk all about how to sand wood, sandpaper, and the best process for sanding a project.
Sanding wood is one of the most important steps in getting the perfect finish on your project.
It can also be the most boring and annoying part.
“I love sanding!” said no one ever… except maybe sometimes you might find it therapeutic.
The process of sanding is very simple. Yet, if done incorrectly, it can cause more damage than benefit.
Sanding is a very crucial step in preparing your project for finishing – whether it is a piece of furniture you built or are simply refinishing it.
So, what is the best way to sand wood? What is the best sander to use? What grit of sandpaper should you use? Do you need to hand sand? How do we make it faster and less dusty?
I am sharing answers to all these questions and more.
- Why do you need to sand wood?
- Sandpaper Grits
- Types of Sanders
- Sanding Setup
- How to Sand Wood
- Why you should not skip sandpaper grits
- Why is my Sander making swirl marks?
- What is the fastest way to sand wood by hand?
- Can you sand wood indoors?
- How do you sand wood without leaving scratches?
- How do you fix uneven sanding?
- Is it better to sand wood wet or dry?
Why do you need to sand wood?
Wood needs to be sanded because the sanding process makes the surface of the wood even. This is important to get good finishing results with painted or stained projects.
Sanding can be done for a number of reasons:
- Sanding removes imperfections in the wood for a better look and finish.
- Sanding opens up the wood fibers to make them ready to accept stains.
- Sanding roughens up the surface to give paint or primer something to stick to and prevent peeling.
- Sanding between coats of paint or poly smooths out any bumps or raised areas for a super smooth, factory-like finish at the end.
Sandpaper is an essential tool used in sanding wood. Sandpaper is a paper or plastic backing with abrasive particles glued to it. These abrasive particles cut wood fibers and hence leading to the effects of “sanding”.
Note, the abrasive particles are NOT sand. They are specifically manufactured for the purpose of sanding.
Sandpaper can be used as is, with hand sanding blocks or with power sanders. There are specific advantages and applications for each and we will discuss those below.
Sandpaper is usually available in various grits. Sandpaper grits specify the size of abrasive particles on the sandpaper. By definition, the grit size is how many particles can fit through one square-inch filter.
This means that the larger the particle, the lower the number of particles in the sandpaper, and hence, lower the grit.
The grit of the sandpaper directly defines the finish you get with it.
- Lower Grit sandpaper (coarse grit sandpaper)> more abrasive > removes wood quicker > rougher finish.
- Higher Grit sandpaper (fine grit sandpaper) > less abrasive > removes wood slower > smoother finish.
There are different grits available ranging from 60 to 7,000. The most common include:
|Coarse||40-80||Rapid removal of material. Removing defects or non-uniformities|
|Medium||100-150||sanding to remove defects from previous steps.
Remove old varnish or finish.
|Fine||180-220||Preparation for finish|
|Very Fine||240-360||Sanding finishes between coats|
|Extra Fine||400-600||polishing of wood|
|Super or ultra fine||800+||polishing of final wood finish.|
So, which grit do you need to use? We will talk about that when we discuss how to sand wood.
Before we dive into that, let’s talk about sanders.
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Types of Sanders
There are many types of sanders available and each has its benefits. If you are just starting out, I highly recommend a sanding block and a random orbital sander.
Random Orbital Sander
A random orbital sander spins randomly in constant overlapping circles or a random orbit. This helps remove extra wood fibers and if used the right way, leaves a smooth surface with few scratches. It has a sanding pad that accepts round sanding discs that are attached using a velcro hook and loop.
There are many random orbital sanders in the market but I highly recommend getting a sander with variable speed and a dust collection port. These are both essential for getting a good quality finish. More about this is below in the tips for sanding success.
I have been using this random orbital sander for almost 6 years and it is still going strong. The key is to use good-quality sandpaper. I use these SandNet sanding discs which are washable and reusable!
A sanding block is great for quick finish sanding by hand. It is great for getting a reliable smooth finish and no scratches (unlike power sanders).
These are usually available are reusable blocks with the sanding sheets sold separately so you can switch out to whichever grit you need.
Also, sanding sponges are a great option for sanding curves, etc.
My favorite sanding block and sandpaper are these. The sanding block has a hard and a soft side making it useful for flat surfaces as well as rounded edges. The SandNet sandpaper is washable and reusable!
Finish sanders or detail sanders have triangular pads and accept triangular sanding sheets. These are specifically designed to help get into tight corners. They also operate in an orbital action but go at a slower speed leading to smoother results. These are great to have to refinish furniture. However, if you are building projects from scratch, you probably don’t need this. I don’t think I have taken mine out in the last 4 years!
Other power sanders
There are a few other power sanders that have very specific functions and capabilities like the sheet sander, belt sander, and spindle sander. These are great to have as you build more complex wood projects or want to be more efficient with your projects.
Sanding is the process of abrading the wood fibers and that means that there are a lot of wood particles that will be flying in the air. Safety is extremely important with sanding.
Do not take your health for granted. Here is the basic safety equipment needed for sanding:
- Respirator – sawdust when inhaled can be carcinogenic. dust masks work but I recommend a good-quality respirator for the best protection. I highly recommend this one.
- Eye protection – the fine dust when flying around can get into your eyes. Use good quality anti-fog safety glasses or goggles. Specifically, the ones that are sealed on all sides so the dust doesn’t get in are perfect.
- Hearing protection – sanders can be loud and when coupled with a vacuum (which we will discuss below) can be even louder. It is important to protect your hearing. Take a look at more information and my favorite hearing protection.
Setting up your workstation the right way for sanding is important to not only get the best results but also for safety. Here are a few tips:
- Pick a well-ventilated area. An open garage or shed is the perfect choice for this.
- Set up a non-slip, non-marring surface to keep your boards while sanding. This will keep your boards from flying away and the other side from getting scratched. The Kreg Project blocks or this silicone mat are perfect for this. If you don’t have one, you can also use an old yoga mat.
- If you are using a power sander like a random orbital sander, hook up a shop vac to it using a small port hose adapter kit. Not only will this make a huge difference in the amount of dust that will fly around, it will also give you better sanding results because it constantly removes dust.
I use this hose kit to connect my sander to the shop vac.
How to Sand Wood
Here is the general process of sanding unfinished wood for a project:
To sand wood, scribble a line using a pencil across the surface. Using a coarse 60 or 80-grit sandpaper and a sanding block or power sander, rub it in the direction of the wood grain until the line has disappeared. Repeat this process using 120 and 180-grit sandpaper. Remove the dust with a tack cloth or vacuum.
Step 1: Scribble a pencil line
Scribbling a pencil mark helps ensure that you are sanding evenly across the board. You do not want to sand one area more than the rest of the board.
Once the scribbled line is sanded away, it is an indication to move to the next area.
The scribbled line isn’t mandatory. However, if you are just starting out, it will be very helpful to make it easier to judge when it’s time to move to the next section. With more experience, you can forego making the line in the middle stages of making the lines and use it during coarse sanding and the final sanding of raw wood.
Step 2: Picking sandpaper grits
Picking the sandpaper grits to use can feel tricky – especially what grit do you start with?
The starting sandpaper grit depends on the type of wood, project, and finish. You do not need to always start with the coarse grit.
Here is a simple guide for how to pick sandpaper grit when sanding raw wood –
- If the wood has a lot of uneven areas and dents, like with an off-the-shelf 2×4, start with coarse sandpaper like 60-grit.
- If it is reasonably smooth already, like a pine 1×3, etc., you can start with 80-grit sandpaper.
- If you are using hardwoods, or if you are sanding to remove dried glue residue, you can start with a medium grit sandpaper like 120-grit.
- For plywood, do not use lower grits as they can wear off the veneer. 120 or 150 is a great grit to start with.
After the initial sanding, you want to go to the next higher grit but never skip more than 60 grit at a time. See why you should not skip grits.
Step 3: Sand the boards
If you are using a hand sanding block, sand in the direction of the grain of the wood applying light even pressure.
If you are using an electric sander like a random orbital sander, or palm sander, keep the sander on the board and turn it on. DO NOT press down on the sander. Your job is to simply hold the sander in contact with the wood and let the sander do its job. In fact, if you press down on it, the sander will run slower because of the friction and will also give you uneven sanding.
Sanding boards for stain
Sanding boards before staining helps get an even stain finish because it helps open up the wood fibers to absorb the stain better.
When you are going to be staining, here is the basic process to follow:
- Start sanding with the lowest grit necessary to get rid of the deepest scratches and go up to the 220-grit in 60-grit increments.
- If using oil-based stains, apply pre-stain conditioner or spray water on the board. This makes the wood rise.
- If using a water-based stain, apply the first coat. You will notice the grain pop as well
- Sand down the raised wood with 220 grit sandpaper until smooth.
- Clean with a tack cloth.
- Apply the stain, or re-apply the water-based stain.
This should give you a smooth finish ready for polyurethane.
Do not sand after applying the stain as this will cause your stained surface to lose its color and get scratched.
Sanding boards for paint
Sanding the boards for paint is just a little different from sanding the boards for stain. You want to only go up to 180-grit sandpaper because the primer and paint need a rougher surface to grip to.
- Start sanding with the lowest grit necessary to get rid of the deepest scratches and go up to the 180-grit in 60-grit increments.
- Apply primer. Wood absorbs the first coat of primer and swells up.
- Sand down the boards with 180-grit sandpaper.
- Apply the next coat of primer. Sand down with 180-grit only if needed.
- Apply 3 coats of paint and sand with 180- grit between the coats.
If needed you can also lightly sand after the last coat of paint.
Sanding boards for the final finish
Whether you have stained or painted your project, when you apply the final finish of polyurethane, polyacrylic, or lacquer, you want to sand with finer grit sandpaper like 220 or 300- grit between the coats. This will give you the best smooth factory finish.
Step 4: Clean up
Once the sanding is completed, you can clean up most of the sanding dust using a vacuum or a brush and dustpan. However, if your next step is to apply a final finish, be sure to use a tack cloth to completely remove all the possible dust from the surface of the pieces of wood.
Now, let’s dive into a few frequently asked questions about sanding.
Why you should not skip sandpaper grits
It may feel like a lot of effort to keep doing the same process with various grits of sandpaper. Why not simply go from an 80-grit to a 220-grit and get it over with?
It is important to not skip grits because each grit is designed to remove the scratches from the previous grit. Every time you sand, the abrasives in the sandpaper leave scratches that are as deep as the abrasive particles.
Each consecutive grit makes the sanding scratches smaller with the smaller abrasive particle sizes.
Skipping too many grits at a time can lead to leftover scratches as well as will increase the amount of time needed to get the results. Therefore, you should never skip more than 60 grits at a time.
Why is my Sander making swirl marks?
The most common reasons for swirl marks are putting too much pressure on the sander and moving the Sander too fast across the surface. The sander should be held in place just enough to support it and let the sander do its job. Another reason for the swirl marks can be poor quality or old sandpaper that is clogged up. This can be solved by switching to better quality sandpaper and connecting dust collection to remove the sanding dust efficiently.
What is the fastest way to sand wood by hand?
The fastest way to sand wood by hand is to use a good quality sanding block with the correct grit of sandpaper. Apply firm pressure and sand in the direction of the grain. Be sure to use the correct sequence of grits i.e., never skipping more than 60 grit at a time to get the fastest and best results.
Can you sand wood indoors?
Yes, you can sand wood indoors as long as you take steps to eliminate or control the dust that results from it. Sanding dust is carcinogenic and you do not want to inhale it. A few things you can do:
- Hook up a good-quality dust collection system or shop vac.
- Use a good-quality respirator (not a dust mask).
- Use a benchtop air filtration system near it.
How do you sand wood without leaving scratches?
The key to sanding wood without leaving scratches is to use the correct grit and the order without skipping more than 60 grit numbers at a time and using a good technique to clear the sanding dust from the surface as you sand.
How do you fix uneven sanding?
Uneven sanding occurs due to over-sanding. Fixing uneven sanding is essentially the same process as sanding:
- Scribble a pencil line across the area
- Sand starting with the relevant grit for the depth that needs to be sanded.
- Once the pencil mark is removed, use the next grit to repeat all the way up 220 grit.
Is it better to sand wood wet or dry?
When working with raw wood, you want to make sure that the wood is dry before you sand it. It is best to dry sand wood at this stage. Wet sanding is when you add water or a lubricant to help remove the sanding dust as you sand. This results in a smoother finish with fewer scratches. This should be done during the final finishing step of the project.
That is it!
That is everything you need to know about sanding to get the best results with your project.
Getting started with woodworking? Here are more tutorials for you:
Your instructions on sanding are very very helpful. As a 68 year old person who has done projects here and there, I have learned so much from you. Thank you