Did your project end up with uneven and undesirable poly finish? Or maybe you’re looking for a quick and easy process to give your DIY furniture a professional look?
Try spray polyurethane and you might not apply poly with a paintbrush ever again! Read on for tips and everything you need about this spray method!
Can You Spray Polyurethane?
Yes, you can apply polyurethane with a spray gun. When spraying, polyurethane leaves a smooth finish free of brush strokes or roller marks. But not all polyurethanes are sprayable.
What is Polyurethane Used For?
You can protect DIY furniture with a layer of polyurethane because it is transparent and long-lasting. You can use it for the walls, ceilings, and trim around your windows, floors, and even your cabinets.
Can I Spray Oil-Based and Water-Based Polyurethane?
Spraying polyurethane yields a beautiful, glossy finish, but if you choose the wrong kind, you could end up with an unsatisfactory appearance. While both types of polyurethane serve the same purpose, water-based and oil-based varieties each have their quirks that should be considered.
Differences Between Water-Based and Oil-Based Polyurethane
#1: Color and Appearance
The most obvious difference is in appearance. Polyurethane spray with a water base looks milky in the can, while oil-based poly looks yellow. Oil-based polyurethane takes on a dark amber color when it dries.
However, water-based polyurethane dries transparent and keeps that quality for the duration of its useful life.
Oil-based poly is great if you want deeper, more vibrant colors. But, only water-based will do if you want the wood’s natural hue preserved.
#2: Drying Time
Spraying polyurethane instead of brushing or rolling helps speed up the drying process, but waiting for oil-based polyurethane to dry can be excruciating. It takes about 5-12 hours for oil-based polyurethane to dry before the second and third coats.
In ideal conditions, another spray coat can be applied to water-based polyurethane in as little as two hours. The quickest time is 4 hours, with fast-drying oil-based ones.
Read More: How Long to Wait Between Polyurethane Coats on Hardwood Floors
#3: Difficulty of Cleaning
You also must consider how simple or complicated it is to clean your tools after use. You can dilute and wash away water-based polyurethane spray with gun cleaning solvent.
Mineral spirits are used to dilute oil-based polyurethane and as a solvent to remove any residue.This is the same method used toclean an oil-based polyurethane brush.As might be anticipated, this is more time-consuming and challenging.
#4: Toxicity Level and VOC Content
Spray polyurethanes are toxic in general. They contain isocyanates and release VOCs  into the air. When sprayed, this toxicity is amplified.
Both types of polyurethane release volatile organic compounds, but oil-based polyurethane releases far more. That’s because more VOC-containing chemicals are required to produce oil-based polyurethane.
While water-based polyurethane is more costly, it speeds up the process and requires less expensive cleaning materials.
How to Spray Polyurethane in 10 Easy Steps
Tools and Materials You’ll Need to Spray Polyurethane
- Spray gun/paint sprayer
- Respirator/Face mask
- Vacuum cleaner
- Mesh filter
- Drop cloth
- Mineral spirits/paint thinner
- Pair of gloves
- 220-grit Sandpaper
- Tack cloth
Step #1: Don Protective Equipment
To avoid harm from polyurethane, you have to at least dress in layers. When working with polyurethane, it’s important to wear protective gear to avoid getting the toxic volatile organic compounds (VOCs) and isocyanates in your eyes, nose, or mouth.
Step #2: Prep the Poly
To get the polyurethane ready, you just need to do these three things:
- Blend the polyurethane by mixing it. Although there are bubbles when mixing or shaking the poly, this will not affect the finish. If the polyurethane has settled to the bottom, stirring it will bring any solids and flattening agents to the surface.
- If you want to filter the polyurethane, use a mesh filter or some old pantyhose.
- A smoother finish can be achieved by diluting the polyurethane, but this step is optional. Following the instructions on the can, dilute the finish with water if using water-based polyurethane or mineral spirits if using oil-based polyurethane.
Step #3: Set Up Your Workspace
Polyurethane finishes are difficult to keep from spreading when spraying, so they often do. To prevent spray from damaging other items in your workshop, lay down a drop cloth.
In addition, you should open the windows a little to let in some fresh air. Put the fan in the opposite direction or turn it off if it blows in your direction.
Step #4: Clear the Surface From Dust
Sand the wood down before you start working on it. To remove all traces of dust from the wood after sanding, use a vacuum or a tack cloth.
Although bubbles are unlikely when using a spray, dust nibs can still be left behind if you don’t take your time.
To prevent dust from being blown onto your work by the fan or outside air, you should also clean any potential dust collectors in the immediate area.
Step #5: Test the Sprayer
Once you have achieved a consistent flow, try it out on a small section of the wood. This is crucial, as the aesthetic appeal to you could make or break the deal.
Wood finished with oil-based polyurethane will take on an amber hue. Water-based polyurethane, despite drying crystal clear, can still result in discoloration or yellowing when sprayed on white-painted surfaces, so testing is advised.
Step #6: Spray the Polyurethane
The three different spray patterns on a polyurethane sprayer allow it to be used on various surfaces. Some examples of possible applications for the spray patterns are provided below.
Applicable when spraying doors, cabinet sides, and fronts, among other vertical surfaces. You can use this method on vertical surfaces, and the spray pattern will either move from right to left or left to right.
This spray pattern is designed for use on flat surfaces such as tables. Thus, the design is a spray that moves both vertically and horizontally.
Step #7: Allow the Wood to Dry
The water-based polyurethane is slower to dry than competing brands. Unfortunately, no other spirits or solvents will hasten the drying process. Heating the surface or increasing airflow is the most effective way to quicken the drying.
Step #8: Sand the Wood
Polyurethane spray paint needs two to four hours to dry before you can reapply polyurethane over the paint. When dry, use 220-grit sandpaper to smooth out any bumps, divots, or runs.
If you sand the wood, be sure to go with the grain. Don’t dig too deeply; you want to leave just enough roughness for the subsequent coat to adhere.
Step #9: Clear the Surface From Dust Again
Take out the vacuum or tack cloth once more after you’re done sanding. You’ll need to be patient because there will still be dust in the air, even after spraying it.
When cleaning, be thorough and aim for any cracks or crevices where dust could be hiding.
Step #10: Spray Another Coat
To apply the second coat, follow the same procedure as before. Make sure the spray is still effective by first using it on an unfinished wood surface.
Following the completion of the second coat, repeat steps 6–9 until the desired finish is achieved. Achieving a smooth finish typically requires three or four coats.
When finished, wait for the polyurethane coating to cure before fully putting any weight on it. This would take about 3 weeks for water-based polyurethanes, and for oil-based polyurethanes, it would take about 4 weeks.
Must-Know Tips for Spraying Polyurethane
- Spraying polyurethane on a vertical surface requires extra care to prevent runs and drips.
- Use light coats of spray and wait for it to dry before applying another.
- Runs can be removed carefully with a razor blade.
- Spray in well-lit areas, and examine the work from various vantage points to ensure you don't miss any spots.
- Before beginning the application, ensure you have all the necessary safety and cleaning equipment.
Best Sprayer for Polyurethane: Top Picks
1. HomeRight C800971 - Top Choice for Water-Based Polyurethane
The three brass spray tips are reliable, and they are resistant to wear and corrosion as well. In addition, it uses only 450W of power, making it ideal for even the most intensive of projects.
The air cap can shoot out in a spherical, horizontal, or vertical pattern. You can also use this on milk paint and chalk paint.
What We Like
- Both indoor and outdoor use is possible.
- Compatible with a wide variety of coatings
- You can switch out the brass tips for different uses.
What We Don't Like
- Can be hard to clean
- There is no viscosity measuring cup included.
2. YATTICH Paint Sprayer - Top Choice for Oil-Based Polyurethane
This sprayer has five copper nozzles and can be used on various poly finishes and surfaces. It has three distinct spray patterns: vertical, horizontal, and circular. The amount of liquid released can be adjusted by turning the volume knob.
With this product, you get everything you need to do the job, including a viscosity cup, a cleaning needle, a brush, a spanner, and a pot with a lid.
What We Like
- It's adaptable to many different coatings.
- 5 different copper nozzles
- Conveniently simple to clean
- It has features that prevent damage from dust and moisture
What We Don't Like
- Not battery-operated
- The paint container is small
Spray Polyurethane vs. Brush: Which is Better?
When working on a flat surface, spraying is the most efficient method because it covers the entire surface in a single pass.
Using a brush allows you to reach into crevices and around edges more easily when working on a project with a curved or angular surface, such as table legs.
Drawbacks of Applying Polyurethane with a Brush
Polyurethane application must take place in a dust-free setting, or you’ll get undesirable results. Air bubbles are common problem with polyurethane when you’re in a dusty room. The surface will be uneven if you let bubbles dry in your finish. Sanding the bubbles is the only solution.
Brushing on polyurethane can be tricky. Long, even strokes should be used when brushing poly. In addition, you should always maintain a wet edge.
Brushing over an area where the poly is dry or just drying will cause you to pull the finish, resulting in bumps when it is completely dry. It will be necessary to sand down these humps before the finish can be applied.
Does Not Give the Best Look on Wood
When applied with a brush, poly can take on a plastic-like appearance despite providing a clear, durable finish.
The polyurethane doesn’t allow the wood to absorb it. If you look closely, you can see that it floats on top of the ground.
Is Spraying Polyurethane Toxic or Safe?
There is no doubt that the VOCs released during the spraying of polyurethane can be harmful to human health.
This is why always wearing protective gear when working with polyurethane is important. Once polyurethane has dried, its toxic effects will cease.
Interesting Read: Is it Advisable to Spray Polycrylic?
Do You Need to Thin Polyurethane Before You Spray?
Polyurethane does not need to be diluted before spraying. Thinning, on the other hand, can help you achieve a more uniform look and feel.
Thin water-based polyurethane with water and mineral spirit or paint thinner for oil-based poly. Test before applying it all over.
Is it a Requirement to Sand in Between Polyurethane Coats?
It is not necessary to sand in between spray coats of polyurethane. All manufacturers or products do not require sanding, but keeping the habit is a good idea.
Dust nibs and uneven application can be removed by sanding between poly coats. The surface is made slightly rougher after sanding, which aids in the adhesion of the subsequent polyurethane coat.
Is spray polyurethane any good?
Spray polyurethane is good. All wood surfaces benefit from being coated with polyurethane spray. This coating is long-lasting, attractive, and sturdy. Using a spray gun to apply polyurethane will produce excellent results.
What's the best way to spray polyurethane?
The best way to spray polyurethane is to focus on applying as thin layers as possible. Keep the sprayer 10 to 12 inches from the surface to avoid uneven coating and bumps. When spraying, a steady, even stream is ideal.
Can I spray Minwax polyurethane products?
Some Minwax products, including Minwax fast-drying polyurethane, are sprayable. Some of Minwax’s polyurethane sprays are oil-based, while others are water-based.
There is no need for a paint sprayer with Minwax’s aerosol polyurethane; it achieves the same results.
Is there a better way to apply poly?
Use a fine paintbrush, foam pad, or cloth to spread a thin layer of polyurethane over the surface. It’s important to go with the grain and not use too much polyurethane, which can cause the wood to warp. After a couple of hours, the first coat should be dry enough to apply a second.
Spraying polyurethane is the quickest way to apply it, excluding cleanup and drying time. Follow our instructions on how to spray polyurethane to achieve a buttery smooth finish without the hassle of a foam brush or roller.
In addition, it’s a snap to apply and provides a polished finish for your do-it-yourself furniture projects.
To achieve the best results when spraying polyurethane, you want to try to focus on applying as thin of coats as possible. This will typically require making faster passes across the product surface, as well as using smaller fluid nozzles (1.0 – 1.4 mm typically) or air assist airless tip sizes.What is the best way to spray polyurethane? ›
To achieve the best results when spraying polyurethane, you want to try to focus on applying as thin of coats as possible. This will typically require making faster passes across the product surface, as well as using smaller fluid nozzles (1.0 – 1.4 mm typically) or air assist airless tip sizes.How much should I thin polyurethane for spraying? ›
You can use mineral spirits, paint thinner, or turpentine to thin oil based polyurethane. Since the final mixture should be 3/4 poly and 1/4 solvent, you'll need to add eight cups of solvent to the mixing container.Should I thin polyurethane before spraying? ›
Thinning polyurethane for spraying isn't completely necessary (unless you want a super smooth finish.) Thinned polyurethane will be able to lay down better, with less texture bumps. It will also dry to a buttery smooth finish.How do you apply polyurethane spray? ›
Use a drop cloth or newspapers to protect surrounding areas from spray mist. Spray light mist coats, holding can 10-12 inches from surface. Move can with a smooth sweeping motion to avoid runs and sags. Several light coats give a better finish than one heavy coat.How do you smooth the last coat of polyurethane? ›
Apply only one thin coat. Then, remove any dust nibs with 1,500-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.What do you use to thin polyurethane to spray? ›
You can use mineral spirits, naptha, lacquer thinner... assuming that you have an oil base poly (not a waterborne). Naptha and mineral spirits are safer choices, but I often use lacquer thinner and even combinations of any of these products.How long do you have to wait between coats of spray polyurethane? ›
Water-based polyurethane requires at least two hours of dry time between coats, and you should only apply two coats in a day. It's important to remember that drying time is affected by temperature and humidity.What is the best thinner for polyurethane? ›
The thinner to use for oil-based varnish and polyurethane is mineral spirits – 3 or 4 parts varnish to 1 part mineral spirits. The ratio isn't crucial. If you prefer to apply these finishes with a rag, thin them with about 50% mineral spirits, essentially creating your own 'wiping varnish'.Why do you add mineral spirits to polyurethane? ›
The mineral spirits will provide a more forgiving coat of polyurethane and will also help any bubbles in the finish to burst before it sets up and dries. Pour the polyurethane into a separate container and add some mineral spirits. A good formula is three parts polyurethane to one part mineral spirits.
Sand Between Coats
Make sure to sand the polyurethane between coats. Sanding removes drips, bubbles and other uneven spots in each coat. Dry the first coat for a full 24 hours. If the coat feels tacky or sticky after that, let dry until it feels completely dry.
Wipe-ons form thinner coats than brush-ons, so use them when wear isn't a concern. Spray-on polys come in handy on hard-to reach surfaces, such as shutter louvers and chair spindles. Aerosol sprays require good technique to avoid drips, and extra prep time to protect surfaces from overspray.Do you shake spray polyurethane? ›
Test Varathane Polyurethane in an inconspicuous area before beginning. Shake the can vigorously before and during use. Use a drop cloth or newspapers to protect surrounding areas from spray mist. Apply light mist coats, holding can 10-12” from the surface and spray with a smooth sweeping motion to avoid runs and sags.How long does it take for spray polyurethane to cure? ›
Surfaces finished with oil-based polyurethanes can be used after around 4 days, but full cure normally takes 30 days. Even if the manufacturer's recommended time has passed, if you can still smell the polyurethane, it probably isn't dry. Fast-drying polyurethane is available in both water- and oil-based formulas.How long does spray polyurethane take to dry? ›
After application, oil-based urethanes take about 24 hours to dry, while water-based urethanes require six hours of dry time. However, there's a significant difference between dry time and cure time. Cure time refers to the time needed before the wood floor is ready to be used.How many layers of polyurethane spray? ›
Generally, a few coats are needed to achieve a smooth surface, as water-based polyurethane is thin; usually at least three coats will do the trick but sometimes as many as five coats will be necessary. One reason why water-based polyurethane is preferred over oil-based polyurethane is because it dries quicker.Why does wood feel rough after polyurethane? ›
Whenever water or any stain or finish that contains water comes in contact with wood, it causes the wood fibers to swell, which is called “grain raising” or “raised grain.” After the water has dried the wood feels rough to the touch, and thinly applied finishes also feel rough.What happens if you don t sand in between coats of polyurethane? ›
#1: Dust and Bubbles Will Get Trapped in Prior Coats
When applying polyurethane for the first time, bubbles are inevitable. Dust specks would appear if the bare wood wasn't cleaned properly before the polyurethane finish was applied or if all the sanding dust was blown onto the wooden surfaces.
Sounds like the poly might have picked up some dust. Try "sanding" its surface with a piece of kraft paper (for example, a piece of a brown paper bag), which is just abrasive enough to polish the surface.What size needle do you use to spray polyurethane? ›
1.3mm: 2-Pack top coats, enamels & polyurethanes.
Polyurethane dries in 24-48 hours and takes about 30 days to fully cure. Your new hardwood floor is installed, and just one more thing needs to be done to protect the wood and bring out that beautiful grain. It's time to apply the polyurethane varnish.What temperature can you spray polyurethane? ›
Standard thermoset polyurethanes can typically withstand temperatures between -80°F to 200°F. However, some polyurethane chemistries can have a higher tolerance to temperature, as high as 300°F. Outside of these temperatures, thermoset polyurethanes will tend to weaken or degrade over time.What thins out polyurethane? ›
Several substances can be used to thin polyurethane including turpentine, mineral spirits, paint thinner or, in some cases, water.What grit sandpaper is best for polyurethane? ›
I use 220 grit. You sand polyurethane to (a) remove any dust bumps in the lower coat, and (b) cut the surface of the lower coat so that the upper coat has more surface area to bond to. You don't need the lower coat to be super-smooth because the upper coat will cover the roughness from sanding anyway.Is mineral spirits or denatured alcohol better for polyurethane? ›
Always use regular mineral spirits (Use mineral spirits if you are using oil-based polyurethane. Use water to dilute water-based polyurethane), not the odorless variety, to dilute the polyurethane; it has greater cutting power. To insure good adhesion, stay with the same brand of polyurethane.Will mineral spirits damage cured polyurethane? ›
Mineral spirits will not affect polyurethane, so a rejuvenator is needed for this. This is simply paint stripper thinned with solvent. It will soften the polyurethane so some of the top material can be wiped off.How do you prevent bumps on polyurethane? ›
- Remove All Dust. ...
- Sand the Surface. ...
- Wipe Down After Sanding. ...
- Mix Your Polyurethane. ...
- Apply Your First Coat. ...
- Sand Before The Next Coat. ...
- Apply Your Next Coat of Polyurethane. ...
- Repeat This Process.
To achieve the highest level of gloss, and to create the smoothest possible finish, wet sanding each coat of polyurethane is the preferred method. It is imperative that polyurethane be allowed to cure thoroughly before wet sanding to get the best results.Can I spray on wipe on polyurethane? ›
Polyurethane is so durable and water-resistant, it has largely replaced shellac and varnish as a wood finish. Originally, it had to be brushed on, but different formulations mean it can now be applied as a spray or by wiping it on with a rag.Do you use a rag or brush to apply polyurethane? ›
What tool do you use to apply polyurethane? Oil based polyurethane can be applied with a natural bristle brush, foam brush, rag (if it's the wipe on type), or a spray on finish. Water based polyurethane can be applied with a synthetic bristle brush, foam brush, rag (if it's the wipe on type), or a spray on finish.
It's best to stay out of the house until the polyurethane is dry and the fumes have dissipated. Once it has dried, it is considered to be relatively safe and non-toxic. However, while it is still wet, it can release fumes that can be harmful to breathe.How do you know if polyurethane is cured? ›
- Full curing time will take 30 days.
- The wood should stop feeling tacky after about 6 hours of application. ...
- Sanding is okay after 6 hours, but you need to clean it thoroughly before adding a new coat.
- Additional coats can be added after 6 hours of initial application.
The poly simply needs to cure for a while. Even after it "dries" and is safe to work on, the solvents that keep the polymers in suspension aren't all gone; they'll continue to evaporate, and the clear coat will fully harden in time. Check the can for your particular product; it should have a full cure time.How do you speed up the curing time of polyurethane? ›
Set up a space heater in an adjoining doorway to keep the room temperature in the 70s F if you are drying the urethane in early to midspring or mid- to late autumn. Outside of the summer months, the need to ventilate might lower the temperature in the room below the optimum for drying urethane.Why wont my polyurethane dry? ›
If you experience oil-based polyurethane not drying well, it's not likely that it's bad polyurethane. It's more likely that the wood you're finishing contains a natural oil or you have applied an oil to the wood and the oil hasn't dried.Will a fan help dry polyurethane? ›
Use a fan to direct fresh air over the area. It can take up to seven days for the urethane to be 90 percent cured and 30 days to be cured completely. However, you should need the fan only for the first day, with periodic use after to remove buildup of fumes.Should you thin polyurethane when spraying? ›
Thinning polyurethane for spraying isn't completely necessary (unless you want a super smooth finish.) Thinned polyurethane will be able to lay down better, with less texture bumps. It will also dry to a buttery smooth finish.How thick should a coat of polyurethane be? ›
The average coating thickness for urethane is 0.032” to 0.058”.Is it better to spray can or brush polyurethane? ›
How to Apply Polyurethane: Brush On, Wipe On, or Spray? Every poly has its preferred applicator, typically a brush or cloth. Some polys also come in aerosol spray cans. Brush-on polys work best on flat surfaces where it's important to build up a durable film.How do you apply polyurethane without streaks? ›
- Use a foam brush or a lambswool applicator instead of a brush. ...
- Use a natural-bristle brush rather than a synthetic one if you are using a bristle brush. ...
- Thin your polyurethane with paint thinner, mixing it with a paint stir stick.
Use a foam brush! It doesn't leave brush marks because it has no bristles. And it's easier to control the amount of polyurethane being applied. It's also easy to gently smooth out any line marks caused by the ends of the foam brush (if too much is applied) and the lines are easy to see and smooth out while applying.What kind of sprayer to use with polyurethane? ›
Airless. As I mentioned above, you're better off spraying water based polyurethane with an airless sprayer — especially if you're tackling a big project. Water-based coating is more affected by temperature and tends to increase in viscosity the cooler it gets — a whole 10 percent for every 10-degree drop!Do you really need 3 coats of polyurethane? ›
Applying three to four coats of oil-based polyurethane to a surface should create a strong and long lasting barrier. Even though oil-based polyurethane is thicker, you still have to apply multiple coats to ensure the entire surface is protected.Do you have to sand between coats of spray polyurethane? ›
Even after sanding, fast-drying and most water-based polyurethanes will remain glossy, which won't help with adhesion. Finally, sanding polyurethane between coats is required for a perfect finish.Should you sand the last coat of polyurethane? ›
If the final coat of polyurethane dries with a smooth finish, sanding the entire surface is unnecessary. However, if you see the material with obvious signs of a rough finish, it's a step we don't recommend skipping.Can you use a rag to wipe on polyurethane? ›
Polyurethane is so durable and water-resistant, it has largely replaced shellac and varnish as a wood finish. Originally, it had to be brushed on, but different formulations mean it can now be applied as a spray or by wiping it on with a rag.Will bubbles in polyurethane go away? ›
If you have larger bubbles that just won't pop with light sanding, you'll have to sand down all the polyurethane. This can be a time-consuming process, but it's the only way to get rid of all the bubbles. Once you've sanded down the surface, you'll start from scratch and apply new coats of polyurethane.