How To Apply Polyurethane – Best Ways to Follow

Trying to be a handyman at home and making your own piece of furniture? That's a great idea! After a period of huffs and puffs, you've successfully assembled your wood project. But something is missing. Your creation doesn't look appealing enough or worthy of display. Why? It still looks "woody", not something that looks like a fine quality, store-bought furniture.

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Your woodwork is definitely screaming hand-made. No worries. I got a perfect solution for you. Why not apply polyurethane to your woodwork?

Never heard of it?

Polyurethane is a type of plastic material that is made by reacting polyols with diisocyanates.eing a flexible kind of material, polyurethane could be found on almost any furniture like mattresses, insulations, foams, elastic fibers and paints.

There are two types of Polyurethane:

  • Oil-based
  • Water-based

types of polyurethane - wood finish

Matte

When it comes to these low-sheen finishes, you have to keep in mind that they have virtually no light reflecting abilities – almost to the point of being dull. And while they’ve been quite popular in the past couple of years, these extremely low luster finishes are not everyone’s cup of tea.

Satin

Next on the sheen spectrum is the satin finish, one recommended by most professionals these days, and with a good reason, too – having a medium to low sheen level, it gets the best of both worlds. It hides dirt and scratches rather well, and the hint of “shine” it has to it enhances the natural beauty of hardwood flooring.

Semi-Gloss

The truth is that the shinier you go with your polyurethane finish, the harder it is to hide the imperfections. For this reason, I wouldn’t recommend it for households with small children and pets.

Oil-based polyurethane is usually a tad bit shinier than the water-based variety, though, so choose wisely.

High Gloss

Having the highest sheen level of all polyurethane wood finishes, high gloss polyurethane is not your typical household finish due to one simple reason – they’re notorious for highlighting all those things you’d rather hide, such as dust, scratches, dents, streaks from cleaning, and water spots.

Which is Better? Oil-Based or Water-Based Polyurethane?


Oil-based polyurethanes are easy to apply but take too long to dry while water-based polyurethanes usually require multiple applications and have a whitish consistency upon application which disappears once dry.

Water-based polyurethane also tends to dry faster. Overall, Polyurethane is the easiest form of finish that even first-timers won't have difficulty in applying.

Oil-Based Polyurethane

Water-Based Polyurethane

Easier to apply

Dries faster

Thicker application

Less odor

Requires 2-3 coats

Requires 3-4 coats

Warmer color

Neutral or clear color

Susceptible to brush strokes

Susceptible to watermarks

Just follow the steps below and you'll have your handiwork ready in no time.

What you will need​

A can of Polyurethane (water or oil based)

Before buying polyurethane, ask the storekeeper about the advantage and disadvantage of both types. Telling the storekeeper the type of wood that you used will also be a big help since there are certain types of wood that easily absorb any compound applied on it.

When it comes to polyurethane wood finishes, one of my personal favorites is the Rust-Oleum Varathane Interior Crystal Clear Water-Based Polyurethane, so be sure to check it out!

A face mask

Polyurethane tends to have a very strong smell. Too much exposure to the fumes sometimes causes dizziness and headache. If you're also very sensitive and tend to have an allergic reaction to fumes, a face mask will be a great help.

face mask

An old tarpaulin, cloth or used newspapers

Avoid staining your carpet or tiled floors with drips. Make sure to line the floor of your workspace with an old tarpaulin. Used newspaper and cloth could also be used especially if the project is just small-scale.

old tarpaulin

Sanding paper in different grits (150, 150, 220 grits)

In order to acquire a good finish, you need to make sure that you have a smooth surface before you apply polyurethane.

use sanding paper to acquire clear finishes surface

Paint brush

There are different types of paint brush that you could use. You could also ask the storekeeper for the best one for your project. Most people normally use fine, soft bristled brush for a smooth finish.

paint brush
If you want something that’s budget-friendly, but handles heavy-duty jobs like a pro, Presa Premium Paint Brushes Set is your best bet! Or if you need more information to choose the best brush for your projects, I also had an article "Best brush for polyurethane."

Lint-free cloth

After sanding the wood, you need to make sure that no grains or wood particles are left. A lint-free cloth will be useful in doing this. You could also use the cloth during contouring by wiping the drips on the sides of your woodwork.

lint free cloth

Wood spatula

If your woodwork has an existing or old finish, you need to remove it first and clean the material. The wood spatula is used to scrape off the paint.

wood spatula

Vacuum cleaner (Optional)

If you have a vacuum cleaner at home, it will be good to vacuum the surface of the material. You could also attach a brush-type hose ender to help remove the grains and particles. Vacuuming your work area will also help since you could avoid having dust particles to be blown away and stick to your wet finish.

use vacuum cleaner

Mineral spirits (Optional)

You could also add mineral spirits to thin your polyurethane. The combination of mineral spirits and polyurethane serves as sealants and should be applied on the surface of the material first .

Additional Info You Might Need Before You Get Started


best way to apply polyurethane finish

There are a few more things you should know before you get down to business:

What’s The Best Way To Apply Polyurethane?

Thanks to different formulations, there’s more than one way to apply a polyurethane finish – and it all depends on the nature of your project.

  • Brush-On – If you’re working on a broad, horizontal surface, such as the floor or a tabletop, you should opt for the brush-on method.
    Beware of brush-on polyurethane if you’re working on a vertical or contoured surface, though, as they’re prone to running and dripping.
  • Wipe-On – Stair balusters, crown moldings, and other vertical, round, or contoured surfaces where brushing might result in drips, call for less viscous polyurethane, which should be applied using the wipe-on method.
  • Spray-On – Whether you’re coating hard-to-reach surfaces or touching-up a damaged finish, spray-on polyurethane is the way to go.

How Many Coats Of Polyurethane Should You Apply?

Well, one thing’s for sure – you’re going to need a minimum of two layers if you want to get the job done right.

Here’s where it gets tricky:

The number of coats depends on the formulation of polyurethane you’re using.

A good rule of thumb is three to four coats of polyurethane, except for wipe-on and spray polyurethane, which require up to six coats to form a functional, protective layer. 

What Can You Do To Thin Polyurethane That Is Too Thick?

Whether it thickened over time or you want to make the finish coat less dense, knowing how to thin polyurethane can come in handy. Here are several substances that will do the job:

  • Water – For water-based polyurethane, thinning it with water is the way to go. Of course, you should check the instructions before you do so.
  • Turpentine – It’s an effective thinner, but it’s smelly, so make sure you mix the two in a well-ventilated room.
  • Paint Thinner – Due to a variety of formulations available on the market, it’s always advised to check if the paint thinner you plan on using can be mixed with polyurethane safely. 

Now, let go to learn how to apply polyurethane to make a smooth finish!

Step by Step Instruction


Step 1 - Prepare your workspace

The first thing that you need to prepare is your workspace. It must be free ofany dust and dirt. Line the floors with an old tarp or used newspaper to avoid staining. Make sure to also have a good flow of air to avoid suffocation from the fumes.

Step 2 - Prepare your material or wood work

Check your woodwork for any old finish like paint, wax or lacquer. Using a wood spatula, carefully scrape the old finish until all of it is removed. Be careful not to cause too many scratches on the wood.

Step 3 - Smoothen the surface of your woodwork

Smoothen the surface of your woodwork with the use of sanding paper. Start first with the lowest grit (100 grit). Afterward, sand the surface again using the 150 grit. Lastly, sand the surface using the 220 grit to avoid any signs of scratches.

sanding and repair before polyurethane finish

smoothen the surface of your woodwork with sanding paper

Step 4 - Vacuum or wipe the surface with a lint-free cloth to remove all the wood grains

To ensure that no grains, dirt, or dust is left on the surface, you could use a vacuum or lint-free cloth to clean it. A clean, dirt free surface ensures a smooth finish.

using vacuum cleaner to keep you surface no dust

use a vacuum cleaner to clean the surface before the next step

Step 5 - Prepare and apply sealant to the surface

In making a sealant, you need to mix two parts polyurethane and one part mineral spirit into a separate container. Mix it well using a piece of stick. Gently apply one coating of the sealant on the surface and wait for it to dry.

Step 6 - Sand the surface again and apply two coats of pure polyurethane

Check if the surface is fully dry. Once it's dry enough, sand it again using a 220 grit. Clean the surface again using the vacuum and cloth, then apply one coating of pure polyurethane. Wait for it to dry. Once dry, sand it again with a 220 grit and apply the second coat.

Note : For every application, make sure to wipe the drips on the sides as well to prevent hardened drips. You could do this by wiping the drips with a cloth.

Step 7 - Wait for 48 hours, then apply the final coat

Let the 2nd coat settle for 48 hours. Afterwards, apply the final coat of polyurethane.

Step 8 - Use a finishing touch

Polishing polyurethane is not only a great final touch but an excellent way to give it its old gloss back if it became dull-looking and worn down, too.

Saturate a piece of wet and dry sandpaper with a 1000-grit in water, sand the polyurethane finish in small, circular motions, and then clean it with a pH-neutral cleanser to remove any visible debris.

After you rinse the surface with water, and pat it dry, squirt a quarter-sized amount of your fine-cut cleaner of choice on a cotton cloth, and spread it all over the polyurethane finish in a back-and-forth motion. Once it’s dry, wipe it away with a damp cloth.

All that’s left to do now is buff the surface to a bright shine with a clean, dry cloth.

Step 9 - Clean your workplace

Make sure to clean your workplace after your work. Hide all the pointy objects to avoid accidents. Also, store the polyurethane and mineral spirit cans on a place not reachable by kids. Both these compounds are very dangerous if kids are exposed to the fumes or accidentally ingest the material. Clean the brushes well using varnish and water to remove traces of the polyurethane and store them in proper storage.

What If You’re Using Water-Based Polyurethane?


Although the application process is pretty much the same, there are a few essential things you should know when it comes to applying water-based polyurethane:

  • Always Use Nylon Brushes – Natural bristles tend to absorb water from the polyurethane finish, which could make them mushy. That’s why you should opt for soft, nylon brushes, instead.
  • Seal Oil-Based Stain – Water and oil don’t mix, everyone knows that – make sure you apply a “barrier coat.” Dewaxed shellac works wonders for sealing oil-based stain.
  • Steel Wool Is A Huge No – Stick with synthetic wool if you’re working with water-based finishes, to avoid finding rust stains in it.
  • Use A Paint Pad For Larger Surfaces – Water-based polyurethane dries fast, which makes it super hard to apply on large surfaces with a brush.

Safety Reminders When Using Polyurethane


No Smoking

Polyurethane is a flammable compound. Avoid lighting and using cigarettes while working with Polyurethane.

Be prepared in case of fire

You never know when a fire can break out while working, so it’s better to be ready in case things go south. Always have a fire extinguisher ready at a very accessible area. Also, make sure that you know how to use one properly.

Safety Gears and Practice

  • Polyurethane Is Known For Having Strong Fumes And Odor. Too Much Exposure Might Lead To Dizziness And Headache.
  • Avoid Exposure To The Fumes By Wearing A Face Mask That Properly Covers The Nose.
  • The Fumes Might Also Cause Irritation To The Eyes When Exposed For A Long Time, So It’s Also Better To Wear Goggles.
  • Allow Air To Circulate Properly On The Workspace. Make Sure That You Have Good Ventilation To Avoid Suffocation.
  • Practice Being Clean And Tidy Especially After Working With Polyurethane. Store It In Places Not Accessible To Young Kids.

Conclusion


There you have it! Your very own handmade furniture that looks like it's straight out from the furniture shop! With its smooth and shiny texture, who would have thought that you just made it with your own hands? How about upgrading all your wood furniture by applying polyurethane? Seems like an amazing idea!

If you get the result you were hoping for by following these steps, share it with us in the comment section and showcase your handy work with our fellow craftsmen. Share these steps to your friends and inspire them to try and do their own masterpiece.

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