Table scratches and stains can be unsightly, but refinishing can get rid of them easily. Knowing how to finish a table top with polyurethane properly lowers health risks caused by polyurethane. Your table will definitely have a new look, gain protection, and last longer!
So, I’ve put together this step-by-step guide to share with you the process of using polyurethane when finishing a table top. Let’s dive in.
Kinds of Polyurethane to Consider for Table Tops
Most poly is either oil-based or water-based. Oil-based poly is the old reliable of the two. Sure, it’s toxic, but it’s got staying power that makes it hard to resist. It’s not just durable but also budget-friendly. And if you’re a sucker for aesthetics like me, the oil-based variety gives you that deep, luscious finish that screams quality.
On the flip side, water-based poly is your friend if you’re into low-risk, easy application. It is easier to apply and only uses water as thinning agent. Unlike oil-based, water-based doesn’t leave yellowish color on the finish over time. Water-based dries faster but requires more application to be tough.
Tools and Materials You’ll Need
How to Apply Polyurethane on a Table Top: 6 Steps
Step #1: Sand the Surface
Poly will effectively stick on a nice and smooth tabletop. Having a course and untidy surface decreases durability of the finish, and you would want to avoid that.
Always, and I mean always, sand in the direction of the grain. You don’t want any weird scratches messing up your beautiful tabletop.
Choose the right sandpaper grit depending on how rough the surface is. For instance, start with 120-grit for new furniture, then go up to 220 and finer. On previously finished wood, use orbital or belt sanders to remove old finish before using finer sandpaper.
Don’t simply apply poly on top of a coated surface. The old coat will eventually peel off, and the new poly will be pointless. Sometimes, removing by sanding won’t be enough, so you might need to apply removing agent.
Step #2: Clear Dust and Debris
Poly decreases effectiveness if it sticks on dust residues instead of hardening directly on the wood surface. A simple trick I do is use a dust blower, vacuum cleaner, or air compressor to blow it off.
If you swipe your hands on the surface, you will notice residues even after blowing off dust. Wipe it with mineral oil using tack cloth/ microfiber.
Sometimes used tables have heat or water stains that gets in the way of your new finish. Temporary heat stains can be removed by heating the affected area with hair blower. However, some old stains might require removing agent.
Step #3: Mix the Polyurethane
The usual ratio is three parts oil-based poly to one part mineral spirit. Meanwhile, you can use water or denatured alcohol  on water-based poly.
You can change ratio depending on your desired thickness. However, I suggest not having more thinner than poly. It will dry slower and affects the overall effectiveness of the coating.
Don’t shake it to avoid bubbles forming. I usually mix it on a separate can to get the right proportion. Stir it slowly while gradually adding thinner.
Step #4: Spread the Polyurethane
When it comes to brushes, stick to a fresh one, as reusing an old paint brush can lead to unwanted discoloration. A useful tip is to pre-soak the brush in thinner, which helps prevent the bristles from drying out quickly.
Cover all surfaces first, starting from the edges, for more efficient work. Get back at it again, along the direction of the grain, once you covered all areas.
As a final touch, skim coat from one side to the other with one stroke of the brush following the grains so that you won’t be leaving lines from brush strokes. Make sure your base coat is even. Brush gently, and don’t leave brush marks or drip before it dries.
Check for thickness inconsistencies. You can spot missed areas by checking the glares. If it doesn’t reflect, it’s probably not thick enough.
Step #5: Allow it to Dry, Then Sand Again
Let it dry for as long as it takes. Thick poly dries quicker in warmer environments. It doesn’t have to be completely dry. It only has to be dry enough to stick with the next coating.
A common issue I run into is the unavoidable dust particles that might settle on the wet surface. Resist the urge to cover it; doing so will only prolong the drying time.
Use wet sandpaper instead (although you can also use dry sandpaper) to remove dust.
Your goal here is to smoothen the texture of your first coat. Gently glide 1000-grit sandpaper across the tabletop, avoiding any kind of pressure.
Step #6: Spread the Second Coat
Apply a second coat once you are done sanding. Simply follow step #4, but you can apply thicker coating if you want.
Repeat last two steps if necessary. But after the final coat, should sand polyurethane? Find out here!
How to Patch Holes in the Table
Patch holes and large abrasions in the table with wood filler or self-leveling sealants. I always make sure the area is dust-free first, either by using a vacuum cleaner or simply blowing the dust off.
Smoothen the top with sanding until it levels with the surface.
How Many Coats of Polyurethane Should you Put on a Table Top?
Aim for three coats of polyurethane for best results. Previously finished tabletop only requires two coats but I recommend making it three coats if you completely removed the old finish.
Thickness can also be a factor. Apply at least five coats on water-based poly to achieve excellent results. And you need more than three coats on a thinly mixed poly to be durable.
Speaking of coating, you should also know how to remove polyurethane from your hands if ever the substance sticks on your skin. So read next!
Self-Leveling Polyurethane for Table Tops
From the name itself, self-leveling polyurethane is used for flattening table tops with uneven surfaces.
It is formulated to be fluid and adhesive, making it highly flexible, and it works just as good as your regular self-leveling sealants, ideal for patching holes, cracks, and rough textures.
It’s also durable and matches well with your poly finish.
See Also: How to Finish Jatoba Wood
How do I get a smooth finish with polyurethane on a table top?
You can get a smooth finish with polyurethane on a table top by smoothening the surface and patching all the holes on the table top before you coat.
Brush the surface with only one stroke along the grains. Then, gently glide 1000-grit sandpaper (or finer) on the final coat. Make it free of dust and add polishing compound if you’re unsatisfied.
Is polyurethane a good finish for a table top?
Polyurethane is a good finish for a table top. It provides excellent protection against scratches, stains, humidity, moisture, and radiation.
It also keeps your table free of termites, extends lifespan, and improves durability and resistance to harsh weather conditions, especially oil-based poly. Polyurethane forms a tough, clear layer that enhances the natural beauty of the wood, creating a smooth and glossy finish.
(But is polyurethane finish waterproof? Find out here!)
Temperature and humidity influence the time it takes for the poly to dry. So when finishing a table top with polyurethane, pick the right thickness and appropriate time with the right weather.
For instance, try thinly dense poly during summer, so it won’t dry faster than it has to while brushing. In contrast, use thicker poly when it’s moist so you won’t have to wait for it to dry longer than you can bear.
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