How Long Does Polyurethane Take to Dry? | Ask the Home Flooring Pros

How Long Does it Take for Polyurethane to Dry? | Ask the Home Flooring Pros

Polyurethane dries in 24-48 hours and takes about 30 days to fully cure.

Your new hardwood floor is installed, and just one more thing needs to be done to protect the wood and bring out that beautiful grain.

It’s time to apply the polyurethane varnish.

But we recommend you don’t charge ahead with a brush and any old can of varnish. It isn’t that simple. “Motor oil is motor oil,” they say, but not all polyurethane is the same. There are different types, as discussed below. And wood conditions differ too. So advance planning saves time and money. Polyurethane varnish can be fussy, and projects can be measured in days and weeks, so it’s best to be prepared.

The type of polyurethane varnish being used, the absorbency of the wood, temperature and humidity are all factors in how long polyurethane takes to dry and cure – two steps that need to happen before the floor is ready for heavy traffic and furniture.

Oil-Based and Water-Based Polyurethane Sealer

Polyurethane is liquid plastic. Polyurethane varnish is made of polyurethane resin dissolved in a liquid solvent. Oil-based and water-based options exist, so it is essential to know which is right for your floor.

Polyurethane varnish is applied by pouring or brushing the solvent onto wood. The oil or water in which the resin is dissolved evaporates over time, leaving the polyurethane resin on the wood in the form of varnish.

Water-based polyurethane varnish dries more quickly and is nearly odorless, so less ventilation is required when it’s being applied. It cleans easily with water and will not yellow with age. In high traffic areas, water-based polyurethane varnish may be less durable.

Oil-based polyurethane requires more drying and curing time than water-based finishes and is the more durable option. The chemicals used require a well-ventilated area during application. Oil-based polyurethane varnish is more resistant to moisture, heat and solvents. It is ideal for high-traffic areas. This finish goes on clear but will age into yellow or amber hues.

Pro Tip: “Oil-Based” and “Solvent-Based” are often used interchangeably as are “varnish” and “finish.”

Drying vs. Curing

Polyurethane varnish is considered to be “dry” when the surface is no longer tacky and doesn’t have a wet appearance. At this point, it is safe to walk gently on the floor. Rough treatment can result in wrinkles in the finish or other surface blemishes, because the varnish underneath the surface is not yet “cured.”

Polyurethane varnish is considered “cured” when the molecules throughout the application have had a chance to chemically interact with oxygen, a process that allows the molecules to bind together more strongly. Each polyurethane finish coat will bind to the coat underneath during curing. Complete curing may take up to a month.

Sheen

Polyurethane varnishes are available in three different sheens, each of which offer different features and characteristics.

1 – High Gloss. A tough and flexible interior/exterior finish, high gloss polyurethane dries to a heavy-duty and very shiny surface. Once considered unsuitable for hardwood flooring because it can be slick, a high-gloss finish is used on the Kahrs Shine collection and others.

2 – Semi Gloss. Drying to a sheen between high gloss and flat, semi-gloss polyurethane is often found on woodwork, furniture, doors, floors, and cabinets. Johnson Hardwood Renaissance Collection is just one hardwood option in semi-gloss.

3 – Satin. Especially fast-drying, satin finish polyurethane varnish provides a durable matte surface and gives wood a subtle gloss, a little shine, and sometimes extra color.

Application

Decide how many applications (coats) of polyurethane varnish will be needed for a particular project. Clean the surface to be varnished. Using a bristle or foam brush, wipe the polyurethane varnish onto the wood in a thin coat. Allow it to dry completely. Repeat the process for each coat.

Pro Tip: Foam brushes are inexpensive and can be thrown away when the job is done.

Factors Affecting Polyurethane Drying and Curing Times

Type of polyurethane. Water-based and oil-based polyurethanes are sometimes modified with drying agents, added oil, extra solvents, and stains (for color.) Each additional component may impact the dry or cure time of the polyurethane. Carefully check product labels and follow package instructions for dry and cure times.

Wood species. Some woods produce chemicals that inhibit drying or curing of polyurethane. Woods like rosewood or aromatic cedar may cause project delays due to their natural oils that slow the process.

Temperature and humidity. General guidelines are based on 70-degree F temperature and 50% humidity. Most . Higher temperatures and/or lower humidity can dramatically lower drying time. Cold, wet days can extend drying time by half a day.

Surface. Raw, sanded wood has an open grain and readily absorbs the first polyurethane coat for a short drying time. Subsequent coats take longer to dry.

Dust and general cleanliness. Dust or other debris can cause imperfections and drying delays in the polyurethane surface. Be sure to properly clean and prepare the surface to receive the polyurethane varnish.

How Long Does Polyurethane Take to Dry

Oil-Based Water-Based Tips
Dry Time Between Coats 24 Hours 6 Hours No shoes or pets
Shoes are OK after: 48 Hours 24 Hours
Furniture can be replaced after: 4 Days 2 Days Use pads on furniture legs
No rugs, mats or similar for: 2 Weeks 2 Weeks Light sweeping only
Full Cure in: 30 Days 30 Days

These are general guidelines. Remember to give the floor 6-12 more hours to dry between when the humidity is high or the weather is cool and damp. Running the AC or a dehumidifier will speed dry times – but be cautious about that if using oil-based poly. You need ventilation too.

Oil-Based Polyurethane Drying Time and Curing Time

  1. 24 hours after application, wood should appear dry and should not feel tacky to the touch. No pets, no shoes.
  2. Sanding is now OK (clean thoroughly after sanding.)
  3. OK to add another coat.
  4. 48 hours after final application, OK to wear shoes.
  5. Four days after application, OK to replace furniture.
  6. Leave the surface uncovered for at least two weeks – no throw rugs or mats.
  7. Full cure after 30 days.

Water-Based Polyurethane Drying Time and Curing Time

  1. Six hours after application wood should appear dry and should not feel tacky to the touch. No pets, no shoes.
  2. Sanding is now OK (clean thoroughly after sanding.)
  3. OK to add another coat.
  4. 24 hours after application, OK to wear shoes.
  5. Two days after application, OK to replace furniture.
  6. Leave the surface uncovered for at least two weeks.
  7. Full cure after 30 days.

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