Tabletops are constantly exposed to stains, moisture, and abuse so it’s important to protect the wood with a durable topcoat like polyurethane. But how do you finish a tabletop with polyurethane?
To finish a tabletop with polyurethane, you need to start by sanding down the wood with 220-grit sandpaper. Then, apply the undercoat, sand, and apply 3 coats of polyurethane.
This post explains in detail how to finish a tabletop with polyurethane including helpful tips to use along the way. Let’s dive in.
What Type Of Polyurethane Can You Use on Table Top?
You can use either oil-based polyurethane or water-based polyurethane on a tabletop. Both types of polyurethane will protect the wood and give a good finish. However, you should know that water-based polyurethane works best when used over an undercoat or washcoat while oil-based polyurethane can be used on bare wood or an undercoat.
Oil-based polyurethane is stronger and more durable than water-based polyurethane. This is because oil-based polyurethane has a higher level of additives in its formula and it also takes longer to cure so the particles harden better and are more resistant to dents, scratch marks, and moisture than water-based polyurethane.
On the other hand, water-based polyurethane dries faster than oil-based polyurethane, has lower toxicity, and is safer and easier to apply. Water-based polyurethane also retains its clear finish for several years while oil-based polyurethane tends to turn yellowish after a few weeks or months.
You should use water-based polyurethane when you are working on an undercoat and you want a color finish on the tabletop. While oil-based polyurethane should be used on tabletops that require protection and durability.
Does Polyurethane Protect Table Top From Scratches and Damages?
Polyurethane does protect tabletops from scratches and wood damage. This is because polyurethane is a durable and flexible top coat that can withstand impacts, scratches, dents, moisture, and other damages to the wood. Polyurethane also repels insects like termites that can cause damage to the wood frame.
Polyurethane is a synthetic top coat or sealant that is reinforced with additives, solvents, synthetic resins, and urethane compounds. Urethane, the key ingredient in polyurethane paint is a plastic-like compound that is flexible, durable, and weather-resistant when dry.
The presence of urethane especially in the polyurethane formula makes the finish very strong and durable enough to protect the wood from scratches and dents.
How To Finish a Table Top With Polyurethane?
Finishing a tabletop with polyurethane isn’t a tough task. As long as you know the right steps to follow, it’ll be a walk in the park and you’ll finish the application in no time.
Luckily, this post explains all you need to know about finishing a table with polyurethane. But before we go on to the steps, let’s check out what you’ll need to carry out the task:
- Sandpaper of different grits
- Polyurethane paint
- Bristled paint brushes
- Mineral spirits
- 4f pumice powder
- A vacuum or duster
- A drop sheet or nylon cover
- A paint or wood stain as an undercoat (optional)
- A shellac-based washcoat (optional)
Here is a quick rundown of how to finish a tabletop with polyurethane:
- Sand the wood with 220-grit sandpaper
- Clean and wipe down the tabletop
- Prep, thin, and stir the polyurethane
- Apply the undercoat or washcoat and leave to dry
- Apply the first coat of polyurethane and scuff it with 400-grit sandpaper when dry
- Apply two more coats of polyurethane
- Buff the polyurethane finish when it has cured.
Next, let’s check out these steps in detail.
1. Sand The Table Top
The first step is to sand down the tabletop. Sanding helps to remove existing finishes, dirt, and dust nibs on the tabletop. Sanding also helps to smoothen the tabletop so the polyurethane can stick and dry smoothly.
Before you sand, ensure to put on a pair of gloves and breathing protection so you don’t inhale the sanded dust. You should also open all windows, air vents, and doors so there is proper ventilation. Lastly, place a large drop sheet or nylon cover on the floor to collect the sanded dust.
Start sanding the tabletop with 150 to 180-grit sandpaper. If there is an existing finish on the tabletop that you want to preserve or use the polyurethane over, you shouldn’t sand with 180-grit. Instead, just scuff the existing finish with 320-grit sandpaper.
But for bare wood or fresh starts, you should start with 150-grit to 180-grit sandpaper. If the existing finish was sealed with varnish, you’ll need to use a paint stripper to remove it before sanding.
2. Wipe And Clean The TableTop
The next step is to wipe and clean the tabletop. This is done to remove the dust that was spread on the tabletop while sanding.
Wiping the wood also helps to remove stubborn stains. For leftover greasy stains and stubborn stains, you can wipe the wood with mineral spirits to remove them. But let the wood dry for at least a day after doing this.
3. Prep The Polyurethane
Prepping the polyurethane should be done based on the manufacturer’s instructions or polyurethane user’s guide. For spray polyurethane, you need to shake the container for a few seconds to mix the content.
For liquid polyurethane, you need to stir the polyurethane to make it flow better. You can stir the polyurethane with a paint mixer or turning stick.
If you are using oil-based polyurethane, you can thin it with 1-part mineral spirits so it is easier to apply. You don’t need to thin water-based polyurethane.
4. Apply An Undercoat (Optional)
Polyurethane is a clear sealant so if you use it on bare wood, it will not give you any color. You can apply an undercoat if you want the polyurethane finish to have color. The undercoat can be a paint, wood stain, or primer coating. Two coats of any of these are enough on the tabletop.
If the tabletop was made from hardwood or porous wood like Oak, it’s better to seal the tabletop with a shellac-based washcoat. This is to stop the wood from over-absorbing the polyurethane finish. Wait 2 hours for the undercoat or washcoat to fully dry before applying polyurethane.
5. Apply The First Coat Of Polyurethane
The next step is to apply the first coat of polyurethane. You can apply polyurethane using a paintbrush but only use a bristled paintbrush.
For oil-based polyurethane, you should apply it with a natural bristled paintbrush. Water-based polyurethane should be applied with a nylon or synthetic bristled paintbrush.
After applying the first coat, leave it to dry. Each coat of water-based polyurethane dries in 4 hours while oil-based polyurethane can take up to 24 hours, especially in moist conditions.
6. Apply Two More Coats Of Polyurethane
When the first coat is dry and hard, sand it with 400-grit sandpaper and dust with a duster. Then apply the second coat of polyurethane and wait for it to dry.
Repeat these steps for the third and final coat of polyurethane and leave it to dry. You are not to sand the final coat of polyurethane.
7. Buff The Polyurethane Finish
When the final coat of polyurethane is fully dry, sprinkle dry 4f pumice powder on the polyurethane finish and apply light oil. Then use a clean and soft rag to buff the polyurethane finish. This makes the finish glossier and more beautiful.
How Long Does Polyurethane Last On Table Tops?
Polyurethane lasts between 5 years and 15 years on tabletops. On average, a polyurethane finish will last a decade when used on a tabletop. The maintenance routine, level of abuse, damage, and stains that the polyurethane finish is exposed to all determine how long the polyurethane finish will last on the tabletop.
However, the biggest factor that determines how long a polyurethane finish on a tabletop will last is the type of surface the polyurethane was used on. On rarely used and low-traffic tabletops like the bedroom table, a quality polyurethane finish will last 15 years.
On medium-traffic tabletops like the dining table or kitchen table, a polyurethane finish will last 10 years. While on high-traffic tabletops like the garage table or workbench, a polyurethane finish will last about 7 years, 10 years at best. This is because garage table tops see the most abuse, stains, and impact.
Here are expert tips to make your polyurethane finish last longer:
- Wipe and clean stains off of the polyurethane finish immediately they occur.
- Don’t expose the polyurethane finish to direct sunlight or it will fade or get discolored.
- Follow the right steps when applying the polyurethane.
- Put waterproof padding on the tabletop when working to prevent scratches.
- Buff and repair polyurethane scratches with a scratchfix pen.
- Don’t place hot items like a soldering iron on the polyurethane finish.
In summary, finishing a tabletop with polyurethane isn’t hard – you just need to know and follow the right steps and you are good to go. Whenever you want to use polyurethane, ensure to sand the tabletop first before applying the polyurethane.
Also, ensure to pick and use the best type of polyurethane. For an aesthetic finish, choose water-based polyurethane. But, for a durable finish, you should use oil-based polyurethane.
Finally, ensure to seal the table if it’s made from hardwood so the polyurethane wouldn’t be sucked into the wood. You can seal the wood with a shellac-based washcoat or a stain-blocking primer coating