More than just a shine, polyurethane sealers protect and preserve the finish you have already put on your floors or furniture. They act as a waterproof top coat to enhance and maintain the beauty of surfaces. Using them as a penetrating agent can prove worthless. But as topcoats, they fight superbly against chips, stains, peeling, scratches and decay.
Many of them provide crystal clear coats, exposing the natural look more beautifully. You always have the opportunity to get the proper topcoat for your project – clear or any other form – because of the availability of many distinctive polyurethane wood sealers.
Is Polyurethane Sealer the Best Top Coat?
Polyurethane sealers are perfect as long as you use them for interior top coating, e.g., study tables, cabinetry, bookshelves, picture frames, and all types of interior furniture. The objects exposed to outdoor extremes shouldn’t have a polyurethane topcoat. Most of them are incompatible with taking the outdoor pressures, except only a few, and those are mainly oil-based.
But when you need a clear coat, indoor or outdoor, there is nearly no alternative except for the use of water-based polyurethanes. But outdoor weather, especially UV and heat, can easily defeat water sealers. Oil-based topcoats with UV protection are quite protective there, but they turn the surface color into rich amber instead of clear. Varnish or lacquer are also durable for exterior projects; however, they also slightly darken the surface.
The only solution left is using a water-based spar urethane – the most reliable protective clear sealer for exterior (interior too) wood exposed to sunlight, water, heat, and wet. However, if you do not intend to have only a clear finish, there are many alternative poly sealers for you.
Best Polyurethane Wood Sealers – Listed Top Coats
We have followed a certain process in choosing the best polyurethane sealer for wood like we do every time. In this case, we have kept in mind the versatility of interior application, extreme exterior conditions, effectiveness on paints and other finishes, and the ability to provide long-term protection and retention of beauty while making the following list.
Best Overall (Indoor & Outdoor) – SEAL-ONCE NANO+POLY or Eco-Poly
Best Clear Coat for Indoor – General Finishes HP or Minwax Wipe-On
Best Topcoat for Outdoor – Arm-R-Seal or Exterior 450 by General Finishes
Best Clear Coat for Outdoor – Varathane Ultimate or Minwax Helmsman
Best Color Sealer – Varathane One-Step Stain + Poly
Honorable Mention – SW Minwax One Coat or CrystaLac Brite Tone
Performance of Polyurethane as Topcoat Sealer
By sealer, we usually mean a sealing agent that protects wood from damage. It can be penetrating or simply acting as a topcoat. Sealers include stain, oil or shellac, where polyurethane is a new addition.
The main function of a polyurethane sealer is to give a topcoat, on painted, varnished, or polyacrylic-ed wooden surfaces (except for stained surfaces), which will act as a protective layer as well as a beautifier. Make sure the varnish on which you’re going to apply poly, is compatible with the sealer. A slightly sanded surface is always good to ensure better results.
Pay attention to the labels. Some poly sealers may require a specific thinner, while some may require a particular way of application. Let the coating cure perfectly (in the manner described in the enclosed manual) to get the most out of it.
You can never get polyurethane topcoats adhered to the commercial-grade sanding sealers, similar to the stains. Using non-poly varnishes or epoxies offers reliable results there. However, covering the stained surface with a shellac coat can make it ready for applying polyurethane sealer. Last but not least, polyurethane sealers are much better on the hardwood than other surfaces.
Clear Top Coat on Paint
Paints are always ready to adhere to any sealer, including polyurethane. When it’s on paint, use double layers of poly sealer with proper curing between two coats. But you must be cautious on the point that clear topcoats over white paint (regardless of brightness level – light or deep) may turn yellowish due to reaction to the white paint substrate.
Although water-based poly sealers do not tend to be yellowish, you still should be careful in terms of white paint. We have been suggested in this case by a few that using a clear chalked paint topcoat is free from yellowing on white paint. We are highly convinced by their logic and results, although we did not practically apply this.
Why Can’t You Add Polyurethane Sealer Over Stain?
Although there are a few exceptions, polyurethane sealers and stains are not designed to bond each other, unlike paint, shellac, or polycrylic. Stains are designed to penetrate wood, while polyurethane sealers are made mainly as a protective coat over the surface. It’s true you’ll find a few poly sealers come up with penetration capacity, but they are very insignificant in number and require compatible stains to adhere.
Applying a clear polyurethane sealer over a stained surface is therefore never the right idea. Firstly, it’ll not offer desired adhesion, and secondly, even if adhesion is given, that’ll not ensure any added protection for the surface. It’s more true when it comes to exterior surfaces, such as the deck, an absolute waste of your bucks! But yes, if the polyurethane topcoat contains good UV protection and is compatible with the stain already on the surface, you can consider going.
Polyurethane Sealer Application
Other than a few differences, applying a polyurethane wood sealer is the same as applying it as the main finish. However, you may require the following stuff –
- Polyurethane sealer
- Bristle brush
- 100-grit and 220-grit sandpaper
- Utility knife
- Polishing compound
- Tack cloth
- Mineral spirits
Now, follow the steps briefed as under –
- As you want protection and beautification through accentuation of the surface inconsistencies, sand the existing finish well.
- Stir the can without shaking it.
- Dilute the sealer if it seems thicker than necessary.
- Use a soft bristle brush and give broad strokes following the grain to cover the entire surface. It may take 24+ hours (oil-based) or 4+ hours (waterborne) to dry.
- Single-coat sealer requires no second or third coat. Otherwise, you may require a second coat once dried. Slight sanding may also be required between coats to remove any stuck dirt or debris. Use a utility knife or razor to remove that if sanding fails to cut.
- Wait till it dries and cures. Shave off any imperfection as instructed in step 5.
Spraying a Clear Top Coat on Wood
If you spray a clear coat on a craft, it will undoubtedly give you the best result. This means that the use of spray cans in small crafting-type projects is surprisingly fruitful. Spraying is very popular in other cases, such as furniture coatings, although it frequently leaves eye-catching stripes on the finish, destroying the real beauty. You should apply a brush or wipe-on there. However, in large projects, such as hall room floor coating, spray guns can perform.
Refinishing with a polyurethane wood sealer can ensure adequate protection to your floor, furniture, and other wooden structures. It enhances the overall glow and beauty of the surface, mainly when you apply the clear one. Remember, using poly sealer means you’re using the most beautiful and safest clear wood finish or topcoat till discovered. Hopefully, this guide with the added list of best products will help you select the proper protective topcoat for your project.
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