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In this article, we’ll explore the respective dry times of various wood sealers, including how long before they are dry to the touch, when you can apply another coat, and the length of time until the finish is fully hardened.
Dry Times for Wood Sealer
The length of time it takes wood sealer to dry is affected by a number of things. The content of the wood sealer makes a large difference, with some finishes drying to the touch within seconds and others taking hours or even days.
Some sealers are not fully hardened by the time they are dry, but move on to a second phase of the hardening process called curing, which also needs to be considered. Certain solvents or additives can also change the drying rate of various finishes.
Finally, the temperature and moisture content of the air can have a dramatic effect on how long it takes your finish to dry.
|Finish Type||Dry to the Touch||Time to Next coat||Fully Hardened|
|Oil-based varnish/polyurethane||24 hours||24 hours||30 days|
|Water varnish/polyurethane||6 – 8 hours||When previous coat is dry||20 days|
|Lacquer||5 – 15 minutes||30 minutes||One week, if well-ventilated|
|Shellac||5 minutes or less||30 minutes for early coats, two hours for later coats, with a 12 hour rest every three or four coats||Two hours|
|Penetrating Oil Finishes||6 – 8 hours||When previous coat is dry||Dependent on formulation.|
Dry Times for Penetrating Oil Sealers
Penetrating oil finishes seep into the pores of wood, forming a flexible but stable barrier.
They go by many names, but the formulation is somewhat standard. Penetrating oil sealants include an oil of some kind (tung oil and linseed oil are the most common)and a solvent or solvents to make it easier to spread and speed dry time.
Whatever formulation is used, the dry time for various penetrating oil sealers is consistent:
- after being allowed to soak into the wood for five to ten minutes, excess oil is wiped off with a rag.
- in six to eight hours, the wood should be dry to the touch and ready to accept a second coat.
Penetrating oil sealers soak into the wood rather than building a thick layer on the surface. They rarely require more than two or three coats for adequate coverage and protection.
Dry Times for Film-forming Wood Sealers
Film-forming wood finishes create a protective barrier on top of wood. They include shellac, lacquer, and varnish. Polyurethane is a type of varnish, and also falls under the category of film-forming wood finishes.
Shellac is a buildable finish, with each coat dissolving into the one beneath it. This means that early coats dry more quickly than later coats. Ten or more layers may be necessary to achieve the desired level of protection and visual appearance. Shellac has minimal resistance to moisture, but is excellent at sealing in odor.
Depending on how many coats of shellac you elect to put on, it can take a total of several days to dry.
For the best results:
- wait 30 minutes to an hour before applying the second coat of shellac, and another hour or so before the third.
- let the shellac dry overnight.
- the next day, wait two hours between each coat to ensure the shellac fully dries.
You can tell if shellac is dry or not by starting to apply another coat. If your brush or polishing pad drags on the surface, the shellac is not fully dry.
Shellac is also the most forgiving of all the film-forming finishes when it comes to temperature and humidity. As long as the ambient temperature is above 40 degrees Fahrenheit, shellac will have no problems drying.
Shellac is made up of two ingredients: resin and denatured alcohol. The ratio of resin to denatured alcohol determines the thickness of the mixture, and is referred to as the ‘cut’.
A heavy cut contains less denatured alcohol and will take longer to dry. A lighter cut contains more denatured alcohol and will dry more quickly. Thus, you can adjust the dry time slightly by altering the amount of denatured alcohol in your shellac.
Shellac is a non-curing finish, which means that no further hardening takes place after it dries. You can place items on the finished workpiece two hours after the final coat.
Varnish (Including Polyurethane)
Varnish cover a wide range of finishes, and dry time can vary dramatically. Generally, varnish takes a look time to dry and cure, sometimes taking over 30 days.
All types of varnish are curing finishes. After they dry to the touch, a chemical process called crosslinking occurs, binding the varnish molecules more closely together and creating an extra hard and tough surface.
Damp conditions slow the dry time of varnish. If working outside, choose a day with minimal humidity and no precipitation. If you must apply varnish on a wet day, consider bringing your work inside and setting up a dehumidifier.
Pay close attention to the weather conditions:
- varnish cures best when left at room temperature or slightly lower – 70 to 75 degrees Fahrenheit. Any lower than that, and curing could take days or even weeks.
- in severely cold environments, you run the risk of the varnish not curing at all.
- if the temperature is too hot, the varnish may dry too quickly for you to correct mistakes, affecting the final outcome.
When varnish is too thick to spread evenly, common advice is to add varnish thinner. Varnish and polyurethane thinners contain various evaporative solvents that will speed the dry time of the varnish, although it will not change the amount of time needed for curing.
Blowing a fan across the workpiece is a decent solution for speeding the dry time of varnish, at least for the first two coats. Any dust or bugs blown into the sticky solution will need to be sanded out before the next layer. Using a fan is not recommended for your top coat of varnish, to minimize the amount of debris.
Pure varnish dries to the touch within about 24 hours, but may take longer to fully harden (cure). Varnish must be sanded between coats to provide a grippable surface for the next layer to cling to. It cannot be sanded until it is completely dry, with no wet, gummy, or tacky spots remaining.
Two or three coats of oil-based varnish are usually necessary for optimal coverage. Thin coats dry more quickly than thick coats, and are also less prone to imperfections.
Oil-based varnish takes about 30 days to fully cure. You should avoid placing things on top of the varnished surface for at least four days. A week would be better. Use your varnished wood gently until it has fully cured.
Water varnishes are often chosen over oil-based varnishes due to their low odor, low VOC offgassing, and significantly shorter dry time. You can apply a second coat of water varnish about eight hours after finishing the first coat.
Water-based varnish protects wood and will not amber over time. However, it doesn’t have the grain-enhancing capabilities of oil varnishes and often flattens the grain. It is best when you want to preserve the natural appearance of the wood.
However, this may not speed up the total time you spend on the project by much. Water varnish is less durable than oil varnish, so five or six coats may be necessary instead of two or three.
Water-based polyurethane and varnish is particularly sensitive to temperature, and will dry very quickly on hot days. If the temperature is over 80 degrees Fahrenheit, consider using a dry-time extender to make sure you have the time you need to perfect the finish before it starts to dry.
Water-based varnish takes about 20 days to fully cure. You can carefully and gently walk on it or set items on it after two days. Rubber mats and other plasticized items are the exception to this rule. Wait for the full curing period to elapse before putting down plasticized items to avoid marking the surface of the wood.
Lacquer is the quickest-drying of all the film-forming finishes, going from wet to dry to the touch in about five to 15 minutes.
Lacquer that is dry to the touch is ready to accept another coat. Dry to the touch doesn’t necessarily mean fully hardened, though.
As a non-curing finish, lacquer dries through the evaporation of solvents. Those solvents may continue to evaporate for days or even a week. Inside cabinets or in areas with poor air circulation, full evaporation of solvents can take months.
You must wait until the evaporative drying stage is complete before attempting to buff out lacquer. If the lacquer is not fully dried it will be pulled away from the wood and form tiny balls on your buffing material.
No sanding is required between coats. Professionals may apply up to six coats in a single work session. Lacquer, whether brushed or sprayed, is generally not recommended for amateurs as it requires experience and/or expensive equipment to do well.
Lacquer thinners are used to modify the thickness of the finish, making it suitable for application with a sprayer onto wood furniture. Chemical retarders can also be added to slow down the dry time.
If you’re trying to determine which wood finish is best for your project, here are a few guides to help you out:
- Shellac vs Varnish
- Shellac vs Lacquer
- Shellac vs Polyurethane
- Lacquer vs Polyurethane
- Varnish vs Polyurethane
- Spar Urethane vs Polyurethane
Dry times vary dramatically between different wood finishes. Shellac dries the fastest, but requires a lot of coats to produce a complete finish. Lacquer is both fast drying and easy to spray, making it the fastest complete finish.
Finishes in the varnish family take the longest to dry and cure, but are highly resistant to sun and precipitation.