Polyurethane Dry Time (Water & Oil-Based): Speed Up Tips

Before you can use a sealed surface, the sealant must dry. So, how long does polyurethane take to dry?

Water-based polyurethane takes 8 hours to dry enough for a re-coat and 24 hours to cure. In comparison, oil-based polyurethane takes 24 hours to dry enough for a re-coat and 48-72 hours to cure.

However, their dry time depends on the temperature, humidity levels, thickness of the coat, and airflow. Also, if you apply thin coats it will dry faster.

Dry Time Between Coats

How Long Should Polyurethane Dry Between Coats?

Oil-based polyurethane must dry 24 hours between coats, while water-based only needs 8 hours between coats. The dry time between coats refers to the time it takes the coating to become hard enough before you can apply another coat.

Oil-based and water-based polyurethane have different drying times because they have different paint solvents. Oil-based polyurethane uses synthetic or natural oil as its solvent, while water-based polyurethane uses water as its solvent. Since water evaporates faster than oil, it means water-based polyurethane dries faster.

However, there are several types, and each type has a different drying time. For instance, satin polyurethane will dry faster than high-gloss polyurethane even if both sealants have the same base or solvent. That’s because the high-gloss finish has more additives and gloss in the paint formula, and that increases the drying time. 

You must wait for the existing coating to dry before applying a new coat. If you re-coat too soon, the finish will turn sticky. That’s because the solvent will be trapped between the coats, and won’t allow the new coat to stick. Since the new coat won’t stick, the finish will become tacky and peel off.

Cure Time

How Long Does Polyurethane Paint Take To Cure?

On average, water-based polyurethane cures within 24 hours, while oil-based polyurethane cures within 48 hours. The curing time refers to how long to wait until you can use and clean the finish.

There’s a difference between the drying time and curing time. Polyurethane dries through evaporation, while it cures through oxidation. The solvent (water or oil) must evaporate for the sealant to dry. However, for the sealant to cure, the oxidation process must be completed.

Oxidization is a process where the chemical particles in the coating react with the oxygen in the atmosphere. In simple words, when the coating cures, the paint particles harden and bond together. 

The finish must cure before you use or clean it. If you clean it before curing (drying fully), the finish will get removed or turn tacky.

How To Speed Up Polyurethane Dry Time?

To speed up polyurethane drying time, increase the temperature around the coating, so the solvent evaporates faster.

Method 1: Apply Thin Coats

Use Paint Thinner

Polyurethane has a thick flow; the thicker the flow, the longer it takes to dry. However, if you apply thin coats, the sealant will dry faster. So, to speed up the drying time, thin the sealant and apply thin coats.

To thin water-based polyurethane, use water. To thin oil-based polyurethane, use mineral spirits or turpentine. If you will spray the sealant, thin it with a ratio of 1:4 (1 part paint thinner 4 parts polyurethane). For a paintbrush or roller, thin it with a ratio of 1:3.

Method 2: Use a Hairdryer

Use a Hairdryer

Since polyurethane dries through evaporation, increasing the temperature (heat) around the coating will increase the evaporation rate. If the evaporation rate increases, the finish will dry faster.

Here’s how to do it:

  1. Plug in the Hairdryer – Turn on the hairdryer and set the temperature heat to medium. 
  2. Move the Hairdryer – Keep the hairdryer 8 inches away from the coating and move it from one side to the other. Don’t keep it over the same spot for too long because the finish will dry unevenly. 
  3. Let the Finish To Dry – You shouldn’t fully dry the polyurethane with a hairdryer because it will dry too fast and peel off. If the paint particles harden too fast, they won’t bond properly, and the finish won’t be durable.

You should use the hairdryer for 5 minutes only.

Method 3: Lower Room Humidity

Lower Room Humidity

The finish will take longer to dry if the moisture content exceeds 50%. However, a dehumidifier will lower the moisture content, and help the sealant to dry faster. 

Here’s how to do it:

  1. Turn On The Dehumidifier – The dehumidifier will draw in air, condense (or remove) the moisture in the air, and release dry air into the atmosphere. This decreases the moisture content and helps the solvent to evaporate faster.
  2. Keep The Dehumidifier Running – You can keep the dehumidifier running for hours. The longer the dehumidifier works, the lower the moisture content will be, and the faster the sealant will dry. 

Method 4: Allow Proper Room Ventilation

Before applying polyurethane, open all windows and doors to allow proper air circulation. If the air is circulating properly, the rate of evaporation and oxidization will increase. This speeds up the drying and curing time. 

Other tips that can help the sealant dry faster are:

  • Use water-based polyurethane because it dries faster.
  • Apply it early in the day before the weather gets hot. 
  • Turn on the fans in the room to increase air circulation.
  • Apply it in proper painting conditions. Humidity should be less than 50%, and temperature should be between 50-80 degrees (F).

Polyurethane is Dry If:

To know if polyurethane is dry, inspect the texture of the finish. If the finish looks wet or tacky, the finish isn’t dry yet. If the finish is shiny and reflective, it has dried.

Another way to know if the finish is hard enough is to use the nail test. Swipe your nail (or a razor) across the coating; if polyurethane builds up in your nail, it hasn’t dried yet. If it doesn’t build up or get removed, it has dried.

You can also use sandpaper. Swipe across the finish fine-grit sandpaper. If the sandpaper clogs up, the coating hasn’t dried. If the sandpaper moves freely and doesn’t clog up, the coating has dried.

Don’t Re-coat Too Soon

If you re-coat polyurethane too soon, the second or third coat will not stick well to the existing coating. This is because moisture (oil or water) will still be trapped in the old coating. The trapped moisture will repel the second coat. If that happens, the finish will be uneven, blurry, and tacky for several days.

When you re-coat it too soon, the existing coating won’t have enough time to hard and become compact.. This means evaporation and oxidization processes will be halted when you apply a new coating.

Since evaporation and oxidization are stopped, moisture will be trapped in the finish. The trapped moisture will prevent the next coat from adhering properly, and the entire finish will turn sticky or peel off.

Also, trapped moisture will bleed through. When a second coat is applied, it seals the existing coat. And, since polyurethane is water-resistant, the trapped moisture will have nowhere to go but stain the second coat. This will cause stains and uneven drying.

The finish will become semi-solid or tacky if you re-coat over a tinted polyurethane too soon.

Final Words

Water-based and oil-based polyurethane have different drying times. Oil-based polyurethane takes 24 hours to dry for a re-coat, while water-based polyurethane takes 8 hours. 

However, you can speed up its drying time by increasing the temperature and air circulation around the coating.

Tony Adams
Tony Adams

Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,

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