What Happens If You Dont Sand Between Coats of Polyurethane? (Answered!)

It may sound easy to apply polyurethane coat on the entire surface, but if you don’t know what will happen if you don’t sand in between coats of polyurethane, the process will be pretty frustrating!

But, what happens if you don’t sand between coats of polyurethane?

So, before you begin sanding polyurethane or adding a coat, we have gathered all the information you require, so you don’t have to worry about it.

VIDEO: How To Sand Between Coats Of Wood Finish

Sanding in between coats of polyurethane is necessary?

 Sanding in between applications is done to remove dust nibs and other defects from the surface.

You should apply the subsequent coat after waiting twenty-four hours, as this will help you develop a more vital mechanical link with the prior coat.

Even after sanding, quick-drying polyurethanes and the vast majority of water-based polyurethanes will retain their glossy appearance, which is detrimental to adhesion.

Therefore, sanding the polyurethane in between applications is the final step that must be taken for a flawless finish.

Why do certain types of polyurethane require sanding in between coats while other types do not?

Sanding between coats of polyurethane can add a significant amount of time to a project.

Because even after their first coat or even their last coat is applied, they will need some time for it to dry, fast-drying polyurethanes are now more widely available than they were many years ago.

This is because they require some time to dry.

It is sufficient to clean the surface of the wood using a specialized type of cloth that has been treated with a sticky substance in between layers of a finish that dries quickly made of polyurethane.

Sanding in Between Coats of Polyurethane is Not Permitted

Many people who work with wood believe that skipping the step of sanding the next layer of polyurethane won’t have any significant consequences.

Why has this topic been posed for such a long time if it is perfectly acceptable to refrain from sanding in the middle of the process of applying a polyurethane coating?

Why bother wasting hours to finish something that won’t significantly impact your life?

What Repercussions Will There Be If I Fail to Sand Between Layers of Polyurethane Coating?

Earlier coats will capture particles of dirt and airborne bubbles.

Before we call it a day, we ensure that the poly is free of dust nibs, bubbles, and other imperfections.

When using polyurethane for the first time, there is a good chance that bubbles will form.

Dust specks would develop on the wooden surfaces if the bare wood wasn’t cleaned correctly before the polyurethane finish was applied.

Dust specks would also appear if all of the sanding dust were blown onto the wooden surfaces.

The Polyurethane Coats That Came Before Won’t Adhere Seamlessly

If you don’t sand the surface between coats of polyurethane, the finish may end up discolored or streaky after it dries.

The formula prevents chemical solvents from combining. In addition, when the first coat of paint has had enough time to dry, a second coat can be applied to guarantee that everything remains in place.

The subsequent coatings of an oil-based polyurethane finish are put on top of the last coat; however, the fusion between the first two layers only sometimes occurs.

It will not be possible to remove any brush marks that have been made.

When applying polyurethane to a wooden floor, one of the most typical issues is the appearance of uneven brush markings-because of this, looking for high-quality foam brushes is essential, particularly if you want one coat of paint to be applied.

It is also essential to ensure that the brush you use for applying the polyurethane is clean to avoid creating uneven brush marks.

The first and subsequent layers of polyurethane coatings may reveal brush strokes from specific products; however, the layer commonly considered the last and final layer would typically disguise these faults.

To sand polyurethane between coats, what grit of sandpaper should be used?

Sanding lightly between polyurethane applications can help prevent the surface from becoming scratched.

In addition, when you sand between layers, the adherence gets better without harming the coating that came before it.

Sandpaper with a grit of 320 is suitable for most uses and will perform admirably.

On the other hand, if you want a faultless outcome, you should use sandpaper with a finer grain, such as 400-grit sandpaper.

When I sand in between coats of polyurethane, can I use an orbital sander?

Between coats, applying a finish with woodworking tools that are too abrasive, such as an orbital sander with sandpaper that has a grit of 220 (or even steel wool), will not produce an attractive surface.

Sanding by hand with a flat block provides greater control, resulting in a smoother and more lasting surface.

Is Sanding Required Before Applying the Final Coat of Polyurethane?

The last coat of polyurethane can be sanded, although doing so will result in scratches and a rough finish.

If the finish is smooth, you should only sand in between applications using fantastic sandpaper rather than sand the final coat.

What is the recommended number of coats of polyurethane to apply?

To achieve a flawless finish, we recommend applying three coats. If the furniture is used sparingly, you only need to apply two coats of paint on it.

Even in high-traffic areas, such as hardwood floors, you should only apply up to three coats of the polyurethane finish.

This will ensure that the finish is protected correctly.

Is It Possible to Apply Excessive Layers of Polyurethane?

Adding more poly coatings than necessary will typically maintain the quality of the final product.

Sanding more coats will take weeks, and you will need to spend more money, offering little protection to the wood.

However, you must do this if you want to protect the wood.

Is It Possible To Apply An Excessive Amount Of Polyurethane Coats To Your Floors?

The maximum number of coats applied to floors and other surfaces is three.

First, choose the best application method for you: a wipe, a brush, or a roller.

For most projects, applying the subsequent coat is all that is required to guarantee the object’s protection for decades.

How much should time pass between coats of polyurethane before the final coat is applied?

Before sanding and applying the next layer of polyurethane finish, each coat must be allowed to dry completely.

While polyurethane made from water can be dry in as little as six hours, polyurethane made from oil can take up to twenty-four hours to cure.

The Four Simple Steps Necessary to Sand Polyurethane

The Instruments and Components That You Will Need

• sandpaper suitable for use on finer surfaces
• Random orbital sander for big surfaces
• Mineral spirit
• Formulation of polyurethane
• A roller, a brush, or an applicator are all options.
• Detergents for cleaning and thinner for painting

1st Step: Preparing the Working Area

Remove any material that may have accumulated on the surface, then wash it with clean water.

Next, scrub the surface with a cleaning detergent to remove any defects that you can find on it.

These imperfections may include stains, grease, pencil marks, and other things.

After cleaning the surface, you should let it dry completely.

2nd Step: Sand the surface.

Make use of papers with lower grits, beginning with a paper with 100 grit and ending with a paper with 150 grit, which is a finer paper.

The finest surfaces and the smoothest finishes can be achieved with a grit of 220.

It is not necessary to use the scuff sand approach.

To ensure that the surface is clear of dust, first wipe it down with a rag that is clean, lint-free, and dampened with mineral spirit.

3rd Step: Apply the Stain (Optional)

You should use an oil-based stain if you use an oil-based poly.

After a water-based stain has dried, sandpaper with a grain of 220 should be used.

It is optional to protect the surface before applying multiple coats of polyurethane because some formulations include both stain and sanding sealer.

If your stain does not act as a sealant, you can try using a polyurethane compound, but you will need to thin it with mineral spirits first.

4th Step: Applying Undiluted Polyurethane Coats

Wait up to six hours for water-based polyurethane to dry before lightly sanding the surface and applying more polyurethane as the subsequent coat when working with this material.

If you use oil-based polyurethane, you must wait up to 24 hours before sanding and applying the second and third coats on top of the first.

Polyurethane can be applied in three weak layers on surfaces such as the floor.

Advantages of Using Polyurethane

Bridges The Gap Between Plastic And Rubber

Polymer goods have a higher load-bearing capacity than rubber goods due to polymers’ higher hardness.

In addition, these formulations bring an additional degree of adaptability to the possibilities offered by plastics.

It is a popular option for finishing surfaces that get a lot of foot traffic, like the floor in the garage.

Abrasion-Resistant

Compared to other types of elastomers, metals, and plastics, the abrasion resistance of polyurethanes is superior to all these other materials.

In addition, it is rated ten times higher than the abrasion resistance of conventional materials due to its unique composition.

Resistant To Both Oil And Chemicals

To reduce the likelihood of chemicals leaking onto other surfaces, most garage floors, kitchen tables, and other types of surfaces have a coating made of polyurethane.

The tremendous chemical resistance of polyurethane makes it an ideal choice for coating surfaces in this category.

Extremely Strong and Hardy

The strength of a material, also known as its resilience, can be measured in terms of its hardness.

Consider using polyurethanes in your formulations if you want the finished product to exhibit a high degree of resiliency after it has been applied to a surface.

The following coat can withstand and absorb shock and conceal any dust left by sanding.

Different kinds of polyurethane coatings and finishes

Sheen Type

When dried, High Gloss offers a surface that is strong yet flexible and lustrous.

A polyurethane formula with a semi-gloss finish produces a sheen between a gloss and a flat finish, while a satin finish produces a durable matte appearance with shine and a touch more color.

The Procedure To Be Followed

How the application is made is yet another aspect to consider.

For example, many people believe that using a wipe-on approach to apply polyurethane varnish to a wood floor is the most effective way to achieve a thin and transparent coat on the surface of the wood.

Water-Based

The longevity of water based poly/polyurethane is inferior to that of oil-based polyurethane.

However, the vast majority of people choose them because they are odorless and do not call for a great deal of ventilation.

Additionally, they dry rapidly, which enables you to finish your projects promptly.

Oil-Based Vs. Solvent-Based

Because oil or solvent-based finishes contain volatile organic components, these coatings must be applied in locations with adequate ventilation.

In addition, these formulations are highly resistant to the effects of the elements and any other possible chemical leaks.

The third additional coat, which contains curing ingredients, dries to a transparent finish when applied initially but gradually turns yellow over time.

What Are Some Alternatives To Sanding Between Coats Of Polyurethane If I Don’t Want To Do That?

Option 1: Select Other Products That Do Not Require Sanding

It is possible to use specific polymers without ever resorting to sandpaper.

Polyurethanes that can be dissolved in water usually fall into this category.

Look for high-quality varnishes that are oil-based and find ones that only require one coat of application.

Option No. 2: Do Not Employ a Glossy Type Of Finish

It is recommended to use a semi-gloss clear finish rather than a satin polyurethane finish since oil-based polyurethanes contain curing ingredients analogous to satin finishes.

When this occurs, sanding marks become more apparent, and successive coatings only adhere appropriately if the surface is sanded first.

Option 3: Use a one-coat polyurethane 

You can implement an alternative technique to avoid the requirement of applying an additional layer.

Even though it contains oil, it dries rapidly, which is a significant benefit of using it.

On the other hand, one-thin coat polyurethane is often quite thick and needs to level off better, making it challenging to work with.

In addition, because the polydimethylsiloxane dries so quickly, brushstrokes, pencil markings, and dust nibs will be noticeable once applied.

Conclusion

Sanding dust the wooden surface many times and applying additional coats could cost significant time and money.

If you omit this step, however, the subsequent coat of polyurethane will not adhere to the one that came before it, and the layer that came before that will eventually peel off, requiring you to buy more of the material and begin the project all over again.

If you still don’t understand what happens if you don’t fine grit sandpaper in between coats of polyurethane, know that skipping the process will cause you to spend much more money in the end!

FAQ on What Happens If You Dont Sand Between Coats of Polyurethane