How do you finish the last coat of polyurethane?
Click to see full answer.
Then, do you sand after last coat of polyurethane?
You shouldn't have to sand the final coat. You apply the final coat, let it dry and you're done. When you sand and rub out the final finish you take off most of the surface which contains the satin. If you are going to do that you might as well use a gloss finish.
Also, how do you fix an uneven polyurethane finish?
- Sand the uneven finish using fine-grit sandpaper. Try not to sand too hard or you may go through into the stain, requiring that you re-stain the area.
- Wipe away dust and debris with a clean cloth.
- Apply a very light coat of polyurethane to the sanded area with a brush.
Furthermore, can you apply a second coat of polyurethane without sanding?
There is no substitute for sanding between each coat if you want the best finish. I get the best result building or refinishing furniture when I thin oil based urethane 3 parts urethane- 1 part mineral spirits for the first coat. Sand with grit after first coat and wipe down with a tack cloth.
What happens if you don't sand between coats of polyurethane?
Q: What will happen to a wood floor if you do not sand between coats of polyurethane? A: Nothing, provided you apply each coat of finish within a reasonable amount of time. If you get dust nibs or brush marks in the finish, sanding will smooth them, and your next coat will look better if you work on a smooth surface.
4 steps to a perfect polyurethane finish
Prepare your workpiece
A glass-smooth finish begins with a level, even surface. To achieve this on open-grain woods (oak, ash, walnut, or mahogany, for instance), first fill the pores with a wood-grain filler, photo below.
Scrape off the excess and let dry. Sand the workpiece to grit.
Quick Tip! Wood-grain fillers come in different colors; you can choose one to blend with the color of the workpiece for an even appearance, or select one that contrasts for more pronounced grain.
Apply stain and poly
Move to a low-dust setting: somewhere without lots of foot traffic and with dust-free surfaces. You can create such an area by hanging an inexpensive vinyl shower curtain in a corner of your shop. With your workpiece wiped clean, apply stain, photo below. (Skip the stain if you intend to leave your workpiece natural-color.) Let dry.
Prepare the polyurethane by reducing it about 10 percent with mineral spirits, unless you're using water-based polyurethane, which doesn't need thinning. Thinning the polyurethane makes it flow on more smoothly and reduces brush marks.
Brush on three thin coats with a foam brush. (You can use a natural bristle brush with oil-based poly, but keep an eye out for loose brush hairs.) Coat the entirety of your workpiece, but don't brush excessively or you'll create areas with too little polyurethane. Allow each coat to dry fully. To give the subsequent poly layers something to bond to, sand lightly between coats with grit sandpaper wrapped around a hard block. Note: The first coat needs the most sanding to appear smooth; don't worry if it doesn't look as flawless as you'd like at first.
Quick Tip! To reveal flaws (bubbles, brush marks, etc.) as you work, shine a light at a low angle across the surface.
After the third coat, sand with grit, then , and finally grit sandpaper. Sand in alternating directions with each abrasive to make it easier to see whether you've removed the scratches from the previous grit. Sand with the grain on the final pass. Then, wipe off the dust with a rag dipped in mineral spirits.
Put on the polish
The final coat gives your workpiece its smooth feel and flawless appearance, so give it extra attention. Spray on this coat using an aerosol polyurethane and let it cure overnight, photo below.
Then, remove any dust nibs with 1,grit sandpaper or a piece of brown paper bag. Finally, using a soft cotton rag or polishing pad, buff the finish to a high shine using automotive paste wax, photo below, which has fine abrasives that polish the finish even further.
Wooden furniture never goes out of fashion, although there are times you need to give it a refresh to make it look its best and to help prolong the life of your furniture.
One of the most common coatings is polyurethane, yet you wonder how you get the perfect finish if you are taking up woodworking for beginners. You will need to go through several phases to get the right finish, and they can comprise dusting, cleaning, waxing, and polishing.
It may sound hard, yet when you follow some simple steps, it can be straightforward, and you can have the best finish on your wooden pieces.
Here you can find out all you need to know about applying polyurethane to obtain the best finish. (Read Best Belt Sander)
What is Polyurethane?
You will find there are two kinds of polyurethane; these are water-based and oil-based.
While they both have used, you tend to find the best finish and protection of your wooden surfaces; the oil-based polyurethanes come out on top.
While it sounds counterproductive, the oil ones are easier to apply. The reason for this is they are thicker and contain more solid compounds. While they take two or three coats, they can offer a depth of shine not achieved by water-based polyurethane.
One of the downsides of obtaining a better finish is that it can be prone to brush marks, and drying takes much longer. With this, you can also find you have a slight run, or there are insects and dust on the surface.
Water is faster drying and looks like milk when you apply it, yet this vanished after drying. Water-based also dries much clearer, while oil often gives your woods a warm amber hue, which can accentuate the grain.
How Do You Sand a Coat of Polyurethane?
Before going into the steps and getting the best finish, you need to understand what happens with your prepping and your first coat.
The best finish begins before you apply your first coat. Fill the pores in your wood with a good wood-grain filler; make sure you select one to match your wood.
Apply your oil-based Minwax polyurethane and let it dry. Once dried, lightly sand the surface with grit sandpaper. You may find it easier to use a sanding block to keep an even pressure. (Read Best Random Orbital Sander For Woodworking)
These are the most basic steps of applying polyurethane to the wood, although there is more to it to get the best results.
What Happens if You Dont Sand Between Coats of Polyurethane?
You find many woodworkers say that sanding between coats is so the previous layer can adhere to the last.
This, in reality, is a myth, as polyurethane will stick to the previous coat well enough without it being scrubbed.
You may find brush marks, yet the biggest issue is that of dust. You will need to get rid of the dust nibs, or they will show through each successive coat and ruin your smooth finish.
How Do You Smooth the Final Coat of Polyurethane?
Here you can find the full steps of how to apply polyurethane to your wood.
1. Pencil Marks
As you are prepping your wood, lightly draw pencil marks across the surface. As you progress through your sanding, redraw the lines, and each time they all disappear, you can move to the finer grit.
Pro Tips: Begin with 80 grit, and finish on or grit. Dont be tempted to go to just yet.
2. Keep a Clean Area
It would help if you had a dust-free area. Vacuum everywhere, including the wood you are working on. Place your workpiece on some plastic sheet if possible (6-mil poly is ideal). One tip is not to begin adding your polyurethane on the day you have sanded.
3. Wipe Your Wood
Take a lint-free cloth and add some mineral spirits. Use this to wipe the surfaces you will be finishing.
One tip is never to use water. It will raise the grain, and you can find yourself sanding one more time.
4. Use the Right Tools
Depending on the size of the piece you are working on, you can find a roller a better option than a brush. Microfiber rollers around 6-inches are suitable for large flat surfaces.
On smaller surfaces, you can opt for a foam brush or wipe on poly instead of soft bristle, although there are times you have no choice but to use bristle brushes. Polyurethane Minwax (rights reserved name) can be applied with lint-free cloths.
Be sure always to clean your rollers and brushes in mineral spirits and put them in plastic bags between coats.
5. Sand with Paper and Pads
When you have each coat laid down, you need to decide which way you want to sand. You can use sandpaper on a sanding block, or you can use synthetic sanding pads.
You can find some woodworkers who use these synthetic pads with orbital sanders to help them get a smooth finish before they add their final coats of polyure-ethane.
You can work up to grit in sandpaper for the coat before your finishing coat. Alternatively, if it doesnt feel too bad, you may be able to get away with using steel wool.
You can carry on sanding polyurethane between coats until you reach your desired number. Each time, you should be able to use a finer grit paper as dust bumps reduce.
How Do You Smooth the Final Coat of Polyurethane?
Woodworkers choose the direction they wish to go, and it is here where they can go for a gloss finish or want a matt polyurethane finish on the wood.
Once you reach the last coat, you will be taking more care than using wipe-on poly.
Again, you have a couple of ways to obtain the best look. If you use the finest grit sandpaper you can get, you will have a silky smooth finish, though be sure to use a sanding block.
You can use synthetic pads rather than fine-grit sandpaper and add some paste; however, doing this, you may see you lose your sheen, although the surface is smooth as silk.
You can also take your steel wool and add some paste wax as you rub it against the surface. (Find the Best Porter-cable )
You will find finishing with polyurethane wax and steel wool will deliver the best finish on your last coat. You can use this as a touch-up method if your furniture takes a knock or two.
*This post may contain affiliate links, which means I may receive a small commission, at no cost to you, if you make a purchase through a link!*
Does It Hurt Your Project To Sand The Final Coat Of Polyurethane? Results Included!
Have you ever wondered if you’re supposed to sand the final coat of polyurethane? The polyurethane can says to sand between coats, but it’s a little confusing as to whether that includes the final coat or not.
So I ran an experiment to determine how the final coat turns out if you sand it (or if you don’t). Here is what I found out:
Sanding the final coat of polyurethane leaves a scratched, rough finish to the polyurethane. To achieve a smooth finish, only sand between coats of polyurethane using very fine sandpaper, and leave the final coat unsanded.
To see for yourself how the finishes turned out, see the pictures of the experiment below.
Let’s dive in!
Quick Navigation: Sanding The Final Coat Of Polyurethane
- What Happens If You Sand The Final Coat Of Polyurethane
- The Final Results: Do You Sand The Final Coat Of Polyurethane?
- Other FAQs About Sanding Polyurethane
- Final Thoughts
- Related Polyurethane & Woodworking Articles
What Happens If You Sand The Final Coat Of Polyurethane
To find out what happens if you sand the final coat of polyurethane, I stained a piece of pinewood and applied 3 coats of semi-glossy oil-based polyurethane (and sanded with grit sandpaper between each layer).
Then for one section of the wood, I sanded the final coat, and the other section I left unsanded. Here are the results:
|Final Coat Unsanded||Smooth, Semi-Glossy||Hard To Scratch*|
|Final Coat Sanded||Scratched, Rough||Easy To Scratch*|
The polyurethane finish was the most notable part of this experiment.
Without the final coat sanded, the polyurethane was smooth and had a nice glossy sheen to it like you’d expect a semi-gloss finish to have.
On the other hand, with the final coat sanded, it sanded through part of the topcoat. That left a scratched, uneven, rough surface.
Not ideal for the final coat of a wood project where you’re expecting a nice and smooth finish.
The other notable part of the experiment was the durability of the polyurethane. Since the sanded final coat ate into a part of the final coat, it took away from the durability of the polyurethane.
I was able to scratch the wood surface with my fingernail because it didn’t have the solid final coat anymore.
For the unsanded final coat, however, I couldn’t scratch the wood with my fingernail because it was doing its job and fully protecting the wood.
The Final Results: Do You Sand The Final Coat Of Polyurethane?
After completing this experiment, I can definitively say that you should not sand the final coat of polyurethane.
You will have a much smoother, clean finish to the topcoat of your wood project if you only sand between coats of polyurethane and skip sanding the final coat.
This result is super positive because now you don’t have to waste your time sanding the final coat! Just sand between the coats if necessary, then apply your final coat, and you’re all done!
Related Polyurethane & Woodworking Articles
Other FAQs About Sanding Polyurethane
Here are some other frequently asked questions about sanding polyurethane to help you achieve a perfect polyurethane finish!
Should You Sand Between Coats Of Polyurethane?
Sanding between coats of polyurethane is beneficial and aids in an extra smooth finish. Sanding between coats is required if there are drip marks, prominent brush strokes, or any other unevenness in each coat. Otherwise, sanding between coats is optional.
What Happens If You Don’t Sand Between Coats Of Polyurethane?
To be honest, I’m kinda lazy, and it seems like a lot of extra work to sand between coats of polyurethane.
So I was curious about what would happen if I didn’t sand between coats. I was surprised with the difference between the finish of a piece of wood that was sanded and a piece that had no sanding between layers of polyurethane.
You can read my article to see the results for yourself.
Final Thoughts On Sanding The Final Coat Of Polyurethane
There you have it! Save yourself some time and skip the sanding on the final coat of polyurethane.
Knowing these little “best practices” of applying stain and polyurethane will level up your woodworking skills and help you create fantastic projects!
Let me know in the comments if you’ve ever sanded the final coat of polyurethane and how it turned out for you. And if you have pictures of it, send me an email with some pictures. I’ll feature some of them on this blog post to help or inspire others!
Catch you in my next post!
Related Polyurethane & Woodworking Articles
Getting The Perfect Polyurethane Finish: Do You Sand The Final Coat?
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Polyurethane final coat of
Refinishing a piece of furniture comes with many questions that you may have a hard time finding an answer to. After you get through the long process you make your way to the final steps, applying the clear coat polyurethane. However, you are now wondering if you need to sand the final coat of polyurethane?
Yes, you can lightly sand the final coat of polyurethane with a grit sandpaper, however, sanding is not required. Sanding can potentially leave a cloudy or scuffed looking surface to your polyurethane finish.
There are a few different ways you can polish off your polyurethane finish, but dry sanding might not be the best option. Let’s look at how we can create a final smooth touch to our poly projects.
How Do You Smooth the Final Coat of Polyurethane?
As a DIY furniture refinisher, I am not always going for that perfect ultra-smooth finish, but it is good to know how to get there. Refinishing dining tables and bookshelves, it’s nice to get as smooth as possible with your final coat of polyurethane. Here I will go over various methods that can be used individually or combined for great final results.
Dry Sanding The Final Coat of Polyurethane Finish
Like I mentioned above, you can sand down your final coat of polyurethane with a minimum of grit sandpaper, any less will almost guarantee a cloudy looking surface. Realistically, dry sanding polyurethane at any grit can potentially leave a scuffed looking cloudy surface.
If you plan to dry sand as a final touch, just do a quick wipe without applying too much pressure. This will lightly sand the surface removing dust particles while reducing the cloudy-looking finish.
If you do this process, I recommend implementing the wax buffing process I mention below. This will hide any scuffs in the finish from dry sanding. So if you already did this and thought you ruined your piece, just buff it out!
Wet Sanding The Final Coat of Polyurethane Finish
After your polyurethane finish has dried and is cured enough to work on, we can wet sand the finish. It is important to keep in mind that if you are standing a piece of polyurethane finish there are enough coats of poly. coats risks sanding through to the wood, apply coats to be safe.
Wet sanding is pretty simple, here’s what to do:
- Pour mineral spirits over the poly finish
- Use a minimum grit sandpaper wrapped around a sanding sponge
- Lightly begin wet sanding in the direction of the grain
- Let the mineral spirits evaporate
Now the finish is smooth and because you chose to wet sand you shouldn’t see any cloudy-looking surface scuffs. Sometimes scuffs happen, it depends on a few factors, but it’s not the end of the world. Following the buffing methods of using wax and steel wool, I mention below can fix up those final flaws. Or applying another coat of polyurethane will hide such sanding scuffs.
Not Touching The Final Coat of Polyurethane
When working on a schedule and time isn’t your best friend you can just leave your final coat of polyurethane without doing any sanding. Honestly, in many of my projects where I apply a clear coat finish, I will sand between coats but not the final one.
If I get that scuffed surface, I need to apply another coat or buff with finishing wax paste. This is a time sucker. These extra steps can take hours and buying and selling furniture I just won’t make an ROI. Plus, most people don’t even notice the surface isn’t glass smooth. But hey, I know if you are a woodworking pro or have your own business going you are pretty keen to get that ultra-smooth touch. So spend that little extra work and get the finish you want.
Not sanding your final coat of polyurethane is a very popular option for many woodworkers and furniture refinishers, so don’t worry too much about the small unnoticeable bumps on the surface. If anything, try to mitigate these issues by wearing clean clothes during the polyurethane coats, dirty clothes can cause dust particles to lay on or mix in the poly causing those little bumps.
Buffing Your Polyurethane To A Smooth Finish
Whether you sanded or not, doing this buffing method using steel wool and finishing paste can create a really smooth finish to your polyurethane piece.
Here is what you do:
- Use fine steel wool and dip it in your finishing paste wax.
- Take your wax-dipped steel wool and rub it back and forth in the wood grain direction on the polyurethane finish.
- Buff out any imperfections in the finish using a fresh piece of steel wool.
Yes, it’s that simple. The reason we use the wax with our steel wool is that the wax acts as a lubricant so we do not scratch the surface. The best wax to use is Minwax Paste Finishing Wax in a natural color. The buffing motion with the steel wool will remove any dust particles that may have reached the surface of the polyurethane before it had dried.
Buffing to this degree is recommend for busy surfaces that need that durable surface. This means tabletops, end tables, nightstands, and coffee tables. Places that aren’t used frequently you can probably skip and just let it be to save you some time. But hey, that’s up to you my friend.
What Happens if You Don’t Sand Between Coats of Polyurethane?
If you do not sand between coats of polyurethane, you risk dust particles causing minor imperfections in your finish. Although sanding between coats is not required it is highly recommended for creating maximum smoothness.
Is One Coat of Polyurethane Enough if Sanding?
No, one coat of polyurethane is not enough to create a durable clear coat finish. It is recommended to apply at least 3 coats of polyurethane to your wood projects.
Since we talk about sanding a piece of polyurethane, if you sand the final coat and you applied one coat of poly, you could quickly go through to the bare wood. This will cause your wood project to quickly become damaged from traffic or water. Seal your poly projects with at least 3 coats at minimum.
Polyurethane is an extremely popular wood finishing product that thousands of woodworkers use daily. Sanding it for a smooth finish is possible, but remember the other methods that are available. Maybe no sanding can work for you too! Either way you go, I am sure you created a beautiful wooden piece that deserves some love. Good luck with finishing your project!
Want a glass-smooth wood finish? The video and article below are one of my most popular, and youll be amazed by what you can accomplish with this wood finishing technique. More than 1,, people have given this video a 95% approval rating. Dont miss the article below, too.
Did you find this video helpful? Im Steve Maxwell, and I create all the content on this website. It would help me if youd consider contributing to my work by buying me a coffee via the button below. A few dollars make a big difference. Thank you!
By the time you finish reading this article and watch the videos here youll know exactly how to create a glass-smooth clear finish on wood, even if youre only using a paint brush to apply urethane. It sounds too good to be true, but it is true. If you pay attention and get the details right, youll be one of those people who can apply a really great finish on interior wood, and do it every time. It all comes down to an operation called buffing.
Why is Polyurethane Finish Buffing So Effective?
Buffing wood is the best-kept secret of the wood finishing world. What surprises me is how few woodworkers know about it considering how often people have trouble creating a wood finish they can be proud of. Buffing can create a glass-smooth finish, even after polyurethane has been applied not-too-well with nothing more than a brush in an ordinary home workshop. Buffing is especially valuable for dealing with the nasty side of waterbased urethane – the brush strokes, the bubbles and the less-than-smooth results many people struggle against. The dirty little secret of the wood finishing world is that waterbased urethane is significantly harder to apply well than its oil-based ancestor. Buffing really does make it easy to get superb results on wood finished with polyurethane, even waterbased. Thats what youll learn about here. Buffing works beautifully, even if youve applied a finish thats not too smooth to begin with.
Most ordinary people who attempt to apply a polyurethane finish eventually resign themselves to sub-standard results, all for lack of one tiny piece of information. But a rough, ho-hum wood finishing outcome isnt inevitable when you understand how to do power buffing. It works perfectly on all flat wooden surfaces, making use of the ubiquitous random orbit sander power tool. Im not talking about using this sander for sanding, but rather for buffing a finish that youve already applied.
How to Buff Polyurethane Finishes
You can power-buff all kinds of finishes wood, metal, and even car bodies. When you get to the bottom of this article, check out my video on how I used buffing techniques to get rid of scuffs and scratches on my vehicles. In this article I’ll show you how it applies here to a polyurethane wood finish – either oil-based or water based. Buffing can transform an ordinary wood surface into one that’s as smooth as glass and very inviting to the touch. And the work takes just a few minutes. Click the video window above to watch an overview of the power buffing process.
Before you do anything else on an actual project, read and understand all the steps below.
Polyurethane Finish Step#1: Start With a Thick Coating
The first thing to understand is the need to begin with a thick polyurethane finish film to ensure that you don’t buff right through to bare wood. Thats not to say you should apply each coat thickly. Four regular coats of urethane applied one over the other is a good starting point. Sand lightly with grit sandpaper between coats, then let the last coat dry for at least 24 hours. This is standard practice with any wood finishing job, and is nothing out of the ordinary. That said, sanding bare wood beforehand to create a smooth foundation is key. Click to watch the video on the right to see how Ive been sanding wood as a professional cabinetmaker since the mids.
Although buffing makes any type of urethane look and feel like glass, might as well use a formulations thats as easy as possible to succeed with. Click here for details of the best urethane Ive used from the options available now.
Polyurethane Finish Step#2: Level the Surface of the Finish
At this stage you’ll have an acceptable surface, but one that’s probably marred by tiny bumps caused by dust that settled on the finish as it dried. This is why leveling is the pre-buffing step required next. Start with one of the old pieces of the grit sandpaper you used to sand between coats earlier, then wrap it around a block of Styrofoam and rub the wood surface lightly in the same direction as the grain. Used sandpaper is best because its gentle. It only takes a few strokes to remove the dust bumps, so don’t overdo it. Also, be sure to avoid fresh sandpaper for this job because it cuts too aggressively. You definitely don’t want to go right through the finish to bare wood. Like I said, use a piece of old grit sandpaper left over from the sanding you did between coats of urethane.
After just a few strokes you’ll find that the surface feels noticeably smoother right after de-bumping, though the sheen will be irregular to the eye. It will be dull where the sandpaper did most of its work, and shinier where it did less. This is normal. As long as the surface feels perfectly smooth, it’s time to move on to the next step.
Polyurethane Finish Step#3: Power Buffing the Levelled Surface
Now comes the fun. It’s time to power buff. Grab your random orbit sander and a piece of superfine 3M rubbing pad. This is a thick, non-woven, synthetic abrasive material available at woodworking outlets and better hardware stores. It comes in different abrasive ratings, and the superfine type is what you need (it’s usually white in colour). I buy mine by mail order. Cut a 6-inch x 6-inch piece, place it on your project, then put your sander on top. Switch on the power. As the vibrations and rotations of the tool are transmitted to the pad and the wood, it buffs the surface, removing tiny imperfections while leveling out the sheen beautifully. Work over the whole area evenly and slowly in a grid pattern. A bright light reflecting off the surface at a shallow angle is the best way to highlight areas that need more work. The more you polish, the shinier the results.
You won’t be able to get a sander into every nook and cranny, and that’s why you should prefinish parts as often as possible before assembly. You can also extend the reach of the buffing treatment using the rubbing pad by hand. You’ll find that the process also works on curved surfaces and trim if you use # steel wool. This ultra-fine abrasive is excellent for buffing, but there’s a danger. Even though it’s metal, fine steel wool can catch fire and burn easily. Store it in a tightly-sealed metal can for safety. Finish up with a coat of paste wax, also buffed out under power, and you’ll have the smoothest possible finish that can be put on wood. You wont be able to resist running your hand over it.
Want to see buffing in action? Click to watch the video tutorial above. The transcript of this video sits below. Also, theres another video further down that explains how to use buffing to restore an auto finish, and the Q&A section.
VIDEO TRANSCRIPT: One of the biggest challenges of woodworking is finishing. Its sometimes a lot easier to build a good project until you get to the finishing part, and thats where disappointment often sets in. This is especially true if youre working in a home shop and youre applying a polyurethane finish with a brush. I want to show you a technique here that will allow you to produce glass-smooth finishes without spray equipment, just using an ordinary brush and polyurethane finish. Now you need to start with a finish of sufficient thickness, so that would be at least three coats of polyurethane, and preferably four. The problem at this stage is that your surface is probably going to have little bumps on it from dust particles that have settled out from the air. There may be some brush marks too, and these are the things that would make the finish ugly. These are the things that Im going to show you how to remove after the fact.
It all comes down to the right kind of abrasion. So what you want to begin with is a piece of fine sandpaper. This is grit, and its wrapped around a piece of foam. This could be styrofoam. This is a little squishier than styrofoam. You dont want to wrap it around a wooden block. You want something with a little bit of resilience, but you dont want to use the sandpaper by hand. Now this sample here has four coats of water-based urethane, and the first step involves knocking off the dust bumps. So, youre just drawing this back and forth across the surface like this.
Youre not trying to remove significant amounts of polyurethane, just to knock off those little high spots. You want to knock off the mountains, and youre going to know if youve done that sufficiently with your fingertips. A little bit of movement of this sanding block with paper on it is going to yield a much smoother finish. Youll feel the difference immediately. Its going to be smooth, but its not going to have an even sheen. Where more abrasion happened, its going to be dull; and where less abrasion happened its going to be shinier.
Further refining the surface is what happens next, and thats where something like this comes in. This is a 3M rubbing pad, so its non-woven. This is the fine grit, and you want to use this, believe it or not, in conjunction with a random orbit sander with no abrasive disc on it. So, the sander causes the rubbing pad to move and polishes the surface. Now if you want a matte polyurethane finish or something with just a little bit of gloss to it, then all you need to use is this fine pad. Itll smoothen things out and give you just the tiniest little bit of sheen. If you want something shinier, youd follow this up with the super fine pad used in the same way.
This is what it looks like. Its really pretty simple. You can turn the speed of your sander down a little bit, at least at the beginning until you get the hang of it. Ill just switch on and start the buffing. Now this is a very flat sheen, so youre not going to see some reflections off of it, but it is extremely smooth. It just feels like a piece of glass, and it didnt start off that way. Now if you want it a little bit shinier, you can continue with the power buffing using this ultrafine pad. Now it feels about the same, but you can see some shinier reflections there. It can get even shinier if you buff more. Youd have quite a bit of control over the level of sheen that you can achieve.
Now not every woodworking situation is as nice and flat and open as this sample piece Im showing you here now, but the same process can be used on any kind of shape or profile. You can start with the knocking off of the dust bumps, and the only difference is that you dont use the random orbit sander for buffing. You just do all the work by hand, and these are flexible enough that they can go around contours and along the edges of panels where they meet stiles and rails, so you can get this kind of result on any surface you might be dealing with.
Got some scratches on your car or truck? Buffing might be able to help with that, too. Click below to watch how I use the process successfully, including the kind of rubbing compound that makes it work. Transcript below.
VIDEO TRANSCRIPT: Many times, when my wife heads into the city with the van here, we come back with some damage. We dont know how this particular scuff happened here, must have happened in some parking lot or something, but Im going to try something to make this look better. I mean, this is not a new vehicle. Its a , but I believe in keeping vehicles good for the long haul, and that means little repairs and fix ups like this if you want to keep ahead of things.
So, what Im going to do is Im going to wash this area to get off any road grit. And then, Im going to use a buffing pad on a random orbit sander with some automotive rubbing compound. Im thinking that this is actually, Im hoping anyway that this is on the surface, that this hasnt actually effected the paint. So, Im going try the mild abrasion of the rubbing compound and hope I can get rid of this white stuff. If I cant, and I really dont know what Im gonna run into yet, Im gonna continue. I have some color matched paint for the van here, and Im going to show you how I would paint over damage like this with paint and clear coat, and then buffing to blend the repair into the surrounding areas.
So first, Ill wash and then well try some buffing.
So, this is my six inch random orbit sander. Ive had this for a long time. Ive sanded a lot of decks and done all kinds of woodworking with it, but it actually is a superb auto polishing tool, as well, if you have the right kind of pad. So, this is a foam polishing pad. Its got a threaded shaft that goes into the machine, just like the sanding pad would. I got this and the rubbing compound on Amazon, pretty convenient. And so, Ive moistened the pad, and I have put on some of the rubbing compound. Ive turned down the speed, too, you dont want it to operate at full rpm. Im gonna start it fairly slow, and then Ill just start buffing here.
The van is a little bit wet. This is a wet process, so I wanna keep it lubed with water and lets see if this works.
Well, I think that things are happening here. I know its not completely gone, yet, but lets just see what we have. And I dont There is something thats definitely going through the paint here. But if you remember, there used to be some marks up here. These are a lot less than they used to be, same with down here.
So, Im gonna continue buffing and just see how good I can get that. While Im at it, Im gonna buff a few other places on the van, too, that have gotten the clear coat scuffed a little bit. But this is a perfect example of how a little bit of TLC can really make a difference. And Im gonna continue, and then show you the result when I get it as good as I can get it.
Well, Im very pleased with whats happened here. Its The buffing that I Please excuse those crows in the background. The buffing approach Ive used has worked very well. This is just great. Theres no need for painting. There are a couple of spots, maybe Ill go at that a little bit more. Down here, too, there was some actual damage. That looks worse close up than it does from a distance, but Im not shooting for perfection here, but this is close enough. I think itll be just fine.
While Im at it, I also polished this headlight lens using the same rubbing compound. Theres a finer grade than this, but I find that this works pretty well for most things. This, Ive just finished and compare it to this one. Its got a little water on it, but it is definitely cloudier. It only took me about five minutes to convert this cloudy lens to this much clearer lens using the buffing compound on that random orbit sander with the abrasive pad.
Polyurethane Finish Q&A
Q: Can I buff a used table that has a pretty good finish? There are minor scratches that you can see, with a few that can be felt with your fingernail. Nothing deep, but a couple of nicks through the finish that Id planned to touch up with Polyshades. So, can I buff as you described, minus the grit on the foam block? I have a 6 orbital polisher to work with. Lord, how Id wish Id known of buffing years ago. Always spent hours trying to get that perfect result. Sprayed a coffee table couple of years ago but got a little overspray of varnish. Can I buff that now, too?
A: I’d definitely start by coloring the minor scratches with Polyshades as you planned. After that, do some gentle buffing and see what happens. I think you’ll be pleased. And you’re right. No sanding with , just gentle buffing. You don’t know how thick the existing finish is, so take it easy.
As for your coffee table, yes, it’s definitely a candidate for buffing, even now. Use the grit paper on a foam block to knock off the dust bumps, the go at it with a “fine” 3M rubbing pad. Thatll give you a nice, matte finish. A little work with the “super fine” will bring up a gloss. The more you use it, the shinier things get. But it’s not like the shine of gloss urethane, which I always find goopy and bad looking. A buffed gloss is a much more refined shine. I hope this helps. Please let me know how you make out.
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Do You Sand the Final Coat of Polyurethane?
It seems like the more you learn about polyurethane, the more complicated it seems. With many conflicting information, different hacks, and new products, it is hard to keep things straight.
In this article, well tackle:
- Do you need to sand the final coat of polyurethane
- How to lightly sand polyurethane for a smoother finish
- What happens when you do or don’t sand the final coat of polyurethane
- How to get bumps out of polyurethane finish
Now, let’s jump straight to it.
Do You Sand the Final Coat of Polyurethane?
No, you don’t need to sand the final coat of polyurethane.
The only time you should sand the final coat of polyurethane is if you havent gotten a smooth finish. Different problems can occur when you apply polyurethane, such as dust nibs, bubbles, and streaks.
If any of these is visible, the job isn’t complete.
How Do You Sand and Smooth the Final Coat of Polyurethane?
Okay, maybe we should start with can you sand polyurethane?
Definitely, YES! And there are two ways on how to get a smooth polyurethane finish through sanding.
- Dry sanding the final coat, which is what most people are familiar with. It involves only the use of sandpaper.
- Wet sanding, which uses a combination of wet/dry sandpaper and mineral spirits or water.
Dry sanding isn’t the best option as it could end up leaving scuff marks on the polyurethane. Remember that sanding scratches the surface of the finish. If you use anything higher than grit sandpaper, the final coat could end up looking cloudy and scuffed.
However, if you must use dry sanding, we will show you how to do it safely.
Before you start either of these, make sure there are enough coats of polyurethane on the surface. If you have only one coat, any type of sanding method will get to the bare wood, and youll have to apply another coat.
How Many Coats of Polyurethane?
Is one coat of polyurethane enough? Hell NO! If you are using water-based polyurethane, make sure you have at least 5 coats, although some people recommend 7 or 8. Most top-quality water-based polys work best with 3 or 4 coats, so if you have a fifth coat and you sand it slightly, you’ll still get maximum protection.
Of course, if you had to apply more coats because the polyurethane raised the grain of the wood, then add an extra layer or two before sanding.
For oil-based polyurethane, coats are also advisable. However, if the product you are working with only requires 2 coats, then sanding the third coat should be just fine.
Also, make sure the surface has cured fully before you start this process. If not, you risk abrading much more of the coat than you would expect and leave a mess.
Now, let us begin with the method for dry sanding.
Tools You’ll Need for Dry Sanding Polyurethane Final Coat
- grit sandpaper
- Sanding block
- Vacuum cleaner
- Tack cloth
- Mineral spirits or water*
How to Dry Sand the Last Coat of Polyurethane
Step 1: Vacuum the Surface
The main reason for sanding the final coat is to get rid of bumps, dust nibs, and other minor imperfections. It is then critical to ensure there is nothing that can cause bumps and an uneven polyurethane finish.
A vacuum cleaner will get rid of any dust particles on wood. It is important to hover across every inch of the space, particularly any crevices in the corners if you are working on a floor.
If you are working on something much smaller, like a chair or a desk, you can use a tack cloth instead of a vacuum cleaner.
Step 2: Wipe the Surface with Mineral Spirits or Water*
After you vacuum the floor, you might still be left with a few dust particles hanging around. To get rid of those, soak a lint-free cloth in water for water-based polyurethane and mineral spirits for oil-based polyurethane, then wipe the floor.
It is okay to use water for both.
This process may not be necessary if your vacuum cleaner did a great job and you were able to use the crevice tool and other bells and whistles. However, it doesn’t hurt to be safe.
Be careful not to drench the floor in liquid. Just a little bit will suffice. If you notice any dust on the cloth, discard it and use a new one.
Step 3: Let the Water Evaporate
Give the surface time to dry again. If you didn’t use a lot of liquid, it shouldn’t take too long. When it evaporates, inspect the surface to see if there are still any imperfections to correct.
There are times that dust on the surface makes the poly look bad. If the problems are still there, then it’s time for the next step.
Step 4: Start Sanding
Before you begin sanding, put on your respirator or face mask. Wood dust can cause different health problems, so dont take any chances, even with a fine-grit sandpaper.
Put the grit sandpaper on a sanding block and gently swipe at the part of the finish with the dents, bubbles, or dust nibs. You want to do this gently in order not to tamper with the smooth parts of the finish.
The sanding block will help you be more accurate. As usual, you should sand with the grain. grit is really fine, but you should still be extra careful, so the finished work doesnt look cloudy or blotched.
Step 5: Clean the Surface
Use a tack cloth and wipe the surface. Check to see if the imperfections are gone. If they are, then your work is done. If it looks better but still not as smooth as you would like, move on to step 6.
Step 6: Use a Finer grit
Move on to a finer grit, using the same technique as before. No matter how tempting it is, don’t sand against the grain, even if you feel like it will get the dust nibs or dents out better.
Repeat steps 5 and 6 until you get a smooth finish.
How to Wet Sand the Final Coat of Polyurethane
As mentioned before, wet sanding is the safer option of the two, as it is less likely to leave your work cloudy or scratched. However, you still need to be careful, so you dont end up abrading too much of the floor.
Tools You’ll Need for Wet Sanding Polyurethane Final Coat
- grit wet/dry sandpaper
- Sanding sponge
- Vacuum cleaner
- Tack cloth
- Mineral spirits or water
Steps to Wet Sanding the Last Coat of Polyurethane
Follow steps of dry sanding.
Step 4: Pour Mineral Spirits or Water into a Cup.
Pour about a quarter-inch of mineral spirits or water into a cup. You should only use mineral spirits for oil-based. However, you can use water even for oil-based polyurethane and still get good results.
Step 5: Soak the Wet/Dry Sandpaper or Sanding Sponge in the Water.
Immerse your sanding tool in the water until it soaks up a fair amount. You can either soak it for 24 hours, in which case you won’t need to pour water on the surface of the polyurethane or soak it for fifteen minutes.
Step 6: Pour Water on the Surface and Start Sanding
Pour a small quantity of water at a time and begin to rub the surface with the wet/dry sandpaper. Sand the imperfections in a circular pattern. The water will prevent the polyurethane from becoming cloudy and keep the sandpaper light’s scratch marks.
Step 7: Wipe the Surface
Water will obstruct your view, so you need to get rid of it often. Constantly wipe the surface with a clean cloth to properly assess your progress. Just as when cleaning the floor normally, don’t repeat clothes. Instead, get a fresh one each time you are wiping the floor.
If the particles you are trying to remove are still there, repeat steps 6 and 7 until you get the desired result.
Step 8: Leave it to Dry, then Buff with a Dry Rag
Once you’ve gotten the imperfections out, leave the surface to dry for 24 hours. When flooring, you can learn how long you should wait between coats of polyurethane on hardwood floors.
After that, use a lint-free rag and buff the surface. The surface will be shiny once again and smoother than ever.
What Happens if I Don’t Sand the Final Coat of Polyurethane?
Nothing happens if you dont sand the final coat of polyurethane. Therefore, you should only sand the last coat if you notice a few minor problems.
However, if there are bubbles, the surface is noticeably uneven, or there are many dust nibs, you should sand between coats of polyurethane as usual and apply another coat.
Can I Use Dry Sandpaper for Wet Sanding?
No, you should not. Dry sandpaper will get clogged quickly, which can ruin your work if youre not careful. Even when using wet/dry sandpaper, you need to be careful not to rub too much of the coat.
Buff Polyurethane Finish When Necessary
Back to your question: Do You Sand the Final Coat of Polyurethane? Well, sanding the final coat is not necessary and is also a rather risky process. When not done correctly, you will need to sand and recoat the entire surface.
If you must sand the final coat, the wet sanding method is safer and gives a smoother or glass-like finish on the wood.
The best solution is to ensure you get the polyurethane application right the first time, so you don’t have to go through this trouble.
Read the battle of polyurethane vs spar urethane to know which one is best for you and your projects.
Goodell is the founder of this website and an avid woodworker. His goal is to help you become a successful woodworker, whether as a hobbyist or as a professional. Goodell has been in love with woodworking for more than two decades.