Sanding Sealer Vs Polyurethane – Which to Choose?

A thirsty product, wood. Except for sealer, it soaks up any liquid that is poured, brushed, or spilled over it. It is therefore practically difficult to achieve a smooth coat when working with porous woods like spruce and cedar without first filling the pores.

To get a stunning, smooth surface, the right sealer must be used. So, between polyurethane and sanding sealer, which will you choose?

If you have experience with wood finishes, you may have already identified an issue with the query. In order to clear up any confusion, we will outline the main distinctions between them and offer guidance on when to utilize each.

Image	Product Name	Editor's Rating	Price
	Sanding Sealer		Check Price
	Polyurethane		Check Price

What is a Wood Sealer?

We must define wood sealer before we can have a discussion about it.

Any compound used as a protective layer on bare wood is a wood sealer. This protective covering could serve a variety of functions, such as:

• preventing water damage to the wood.
• minimize the negative effects of UV radiation.
• Keep the wood’s beauty intact.
• Before other finishes can be applied, provide a coat.
• Extend the wood’s useful life.

Shellac, stain, lacquer, varnish, or polyurethane are a few examples of wood sealers that can be either oil- or water-based.

As you can see, some of these wood finishes have unique characteristics and serve various purposes. While some of these sealers function flawlessly on their own, others require assistance.

Sanding sealer can help with that.

What is a Sanding Sealer?

The grain rises when liquid is applied to bare wood. You might need to repeat this procedure multiple times to acquire a smooth finish because the elevated grain needs to be sanded. You need a sanding sealer to avoid using too many coats of your finish.

Sanding sealer is simple to sand, thus the name, and it enables you to treat the wood evenly. Even when pore filler is used, sanding sealer is beneficial.

Lacquer with zinc stearate is the most popular kind of sanding sealer. The lacquer is easy to sand thanks to the zinc stearate, a soft, fluffy soap.

Dewaxed shellac is an additional kind of sanding sealer. Shellac flakes that have been dewaxed can be dissolved in mineral spirits to create a sealant.

Sanding Sealer Pros and Cons

PROS

• Easy to apply
• Dries rapidly
• decreases the overall work time and reduces topcoat costs

CONS

• All topcoats are incompatible with it.
• It cannot be applied as a concluding step.

What is Polyurethane?

A long-lasting, water-resistant finish with a hard drying time is polyurethane. Although it can be used to refinish furniture, it is most frequently used to coat floors, tables, fences, and other surfaces that require water and scratch resistance. Polyurethane is rarely utilized for high-end furniture because of how thick it may be.

There are two primary varieties of polyurethane wood sealers:

polyurethane with an oil base.

polyurethane with a water base.

Although oil- and water-based polyurethane perform the same function, they both have particular benefits and drawbacks. For instance, oil-based polyurethane, which over time turns yellow, gives wood a warm glow. Water-based poly, on the other hand, dries and stays crystal clear.

When sprayed and maintained properly, both forms of polyurethane can shield hardwood surfaces for more than ten years. Nevertheless, urethane-based materials start to flake slightly after being sanded.

Polyurethane Wood Sealer Pros and Cons

PROS

• The lengthy thick coat is durable
• Waterproof, chemical, and scratch resistant
• dries quickly and is durable enough to withstand heavy use.
• It can be used in a variety of ways.

CONS

• Drying takes a very long time.
• Emits significant amounts of VOCs

A detailed feature comparison between sanding sealer and polyurethane sealer for wood

Any woodworking project’s success is determined by the way it is finished. No matter how well you cut, measured, joined, carved, etc., it won’t look fantastic unless the topcoat is applied correctly.

You can use polyurethane or sanding sealer and a complementary finish, depending on what you’re working on.

Although polyurethane and sanding sealer don’t exactly perform the same function, this comparison will take into account the requirement to apply a finish to the sanding sealer. Paradoxically, the topcoat in some situations may be polyurethane; however, more on that later.

1. Polyurethane vs. Sanding Sealer: Level Finish

This is a good spot to start our comparison since the main goal of sanding sealer is to ensure equal application of the wood finish.

An excellent way to guarantee that finishes like lacquer and dewaxed shellac are flat on the surface of the wood is to use sanding sealer. If you don’t, the project can feel thinner in some places than others.

Also, it guarantees that you won’t need to sand between lacquer applications to smooth down elevated grains or level the final film.

Since polyurethane sealer for wood is applied as a film coat rather than being absorbed into the wood, unevenness is rarely a concern. Moreover, most polyurethanes self-level. Sanding between applications is a necessity nonetheless to ensure a level final coat.

Both products will assist you in obtaining the smooth surface that makes your job appear flawless because, in essence, the first coat of polyurethane will perform the same function as the sanding sealer.

Decision: a tie

2. Polyurethane vs. wood sealer: how many coats?

Using a sanding sealer will let you apply less coats, which is the second important benefit. A water-based topcoat will typically elevate the wood fibers when applied directly to wood, even dyed wood.

To achieve a flawless finish, you will need to sand down these hair-like strands. You must apply another coat after sanding, then repeat the process until you achieve the desired texture.

A sanding sealer will elevate the wood’s grain when you use it. Usually, the job is finished after sanding the first coat and applying a second. As a result, you won’t need as many layers while applying the topcoat.

For instance, you may use one coat of sanding sealer and three coats of lacquer instead of five layers of lacquer.

Contrarily, water-based polyurethane will elevate the grain a few times, necessitating the application of many coats. On a table, it’s typical to need seven applications of water-based poly before the desired smoothness is achieved.

But, oil-based polyurethane doesn’t have that issue, so don’t get carried away. All you’ll need is two to three coats of paint to achieve an immaculately smooth finish, provided you correctly sanded the raw wood.

As a result, applying oil-based polyurethane will require less coats than applying a sanding sealer first. For any other type of finish, a sanding sealer will significantly cut down on the amount of coatings required.

Conclusion: Sanding Sealer

3. Polyurethane Sealant for Wood vs. Sanding Sealer: Drying Time

The time it takes for each coat to dry must be taken into account when discussing the number of coats. Since it is applied in thin coats, lacquer is one of the finishes with the shortest drying times. You might be prepared to add another layer in an hour.

Therefore, is it worthwhile to first use a sanding sealer in order to save a few applications worth the hassle? Sanding sealer may be equally as quick, based on the brand.

In just one hour, Minwax sanding sealer dries, making it ready for a second coat or your first coat of polyurethane.

Before you can apply the second coat, the sanding sealers from Sherwin Williams and Benjamine Moore both require at least 3 hours of drying time. That implies that during this time, you may have applied three coats of lacquer or another quick-drying finish.

The polyurethane drying times are well-known. After a thorough sanding procedure, oil-based polyurethanes take up to 12 hours before the next coat may be applied.

Yet, depending on the type and application technique, water-based polyurethane might dry in as little as two hours.

Polyurethane coatings dry significantly more quickly when applied by wiping or spraying, without sacrificing durability.

Hence, utilizing water-based polyurethane may be the quicker method, unless you are using a sanding sealer that dries exceptionally quickly.

Conclusion: polyurethane

4. Polyurethane vs. Sanding Sealer: Adhesion

Polyurethane vs. Sanding Sealer: Adhesion

The comparison between these two items falters in this particular area. When applying polyurethane to a surface, you keep going until the desired effect is obtained. No additional product is put on top of it.

But you need to apply a different finish when using a sanding sealer. Sanding sealer has the drawback that you have to use the proper one that matches the base.

For instance, you can only coat lacquer over a sanding sealer comprised of lacquer and zinc stearate. When using dewaxed shellac, the same rules apply.

Sanding sealer doesn’t get along well with other materials, which is why. Some businesses even advise customers to only use their sanding sealer with their goods.

If you already purchased the sanding sealer or would like to try some different things, this can be frustrating. It won’t stick to the sealer if you don’t apply the proper finish.

Naturally, polyurethane doesn’t have an issue with it since you are just putting more of the substance on itself. It will adhere perfectly as long as you sand in between coats.

Conclusion: polyurethane

4. Polyurethane vs. Sanding Sealer: Versatility

You should rethink your strategy if you are counting on sanding sealer to speed up all of your finish treatments.

Although while sanding sealer is fantastic, it has one obvious drawback: it can only be used on bare wood. It seems sense that sanding sealer won’t work on other surfaces because its main function is to stop the finish from leaking into the grain.

Sanding sealer simply won’t stick to an already applied finish, and you won’t need to use it. For coloured wood, you can apply sanding sealer, but this step might also be superfluous.

Polyurethane, on the other hand, may be used on almost everything. Polyurethane may improve a surface whether it is unfinished, stained, or even completed. Polyurethane can be used to seal paint and other surfaces.

Conclusion: polyurethane

5. Polyurethane vs. Sanding Sealer: Ease of Application

One thing you might hear folks grumble about is how tough polyurethane application is. Brush streaks could result from brush use. You could produce roller lint when using a roller.

Even so, you still have to wait hours between coats before sanding the entire surface and doing the dance all over again. For some who don’t like the scent of polyurethane, that can be upsetting.

We now have water-based polyurethanes that don’t require sanding in between coats because of this. You can also use a brush, pad, roller, wiping cloth, or sprayer to apply polyurethanes.

Sanding sealers, on the other hand, are normally applied using a synthetic brush. The stearate softens the lacquer, making it simple to sand each coat.

Although commendable, polyurethane has a much wider range of applications. Even when you don’t need to sand it at all, sanding water-based polyurethane is more difficult than sanding sealant.

A water-based polyurethane can be cleaned similarly to a sanding sealer. Just some soap and water will do. Use denatured alcohol or mineral spirits to clean the brush if you used dewaxed shellac rather than lacquer sealer to seal the wood.

This is another definite win because polyurethane offers all the advantages and more.

Conclusion: polyurethane

6. Durability of polyurethane versus sanding sealer

These two candidates pass the ultimate test for a high-quality product—how long it lasts.

You fully anticipate the sanding sealer to keep the topcoat intact for as long as possible while using it. Sanding sealer can accomplish that as long as you don’t apply too many coats.

You don’t want a lot of zinc stearate remaining after applying the lacquer finish because it makes the lacquer soft. Even while lacquer is a strong finish, it can also be fragile, thus applying it over a heavy coat of sanding sealer will probably cause it to shatter or break.

Because of this, you must sand everything down after applying no more than two layers of sanding sealer. Although not all sanding sealers will completely plug the wood grain’s pores, the rest is not required.

By accident using three coats, the finish might not be long-lasting.

You won’t run into that issue with polyurethane. You can never apply too many coats of polyurethane because it is one of the strongest, longest-lasting wood treatments available. In theory, yes, but adding further two or three coats won’t make the product any less durable.

Conclusion: Polyurethane

Final Decision: Polyurethane vs. Sanding Sealer

Although it was unreasonable to compare polyurethane and sanding sealer in the first place, the comparison had to be made to dispel any misunderstandings.

What you are working on will determine the product you employ.

Sanding Sealer Conclusion

Whether working with porous woods, raw wood, or adding a finish like shellac or lacquer, use sanding sealer.

When applying poly, you can use sanding sealer, although it’s not required.

Polyurethane Conclusion

All timber surfaces are incomparably protected by polyurethane, which is also incredibly durable. No matter how porous the wood is, polyurethane can be applied to it and still produce excellent results.

If you only need a few coats or don’t need to sand in between applications, it’s better to use polyurethane alone. Alternatively, you would save time and money by sanding sealer.

Don’t forget to read our comparison of Benjamin Moore Aura and Regal.