How Long Does Spray Paint Really Take to Dry?
Do you relate to the phrase, "it's like watching paint dry?" Well, spray paint generally dries faster than brushable paint. Let's find out how fast.
Spraying paint is much faster and more efficient than brushing it, and spray does a better job, too. You’ll get a smooth finish free of brush strokes, and the spray settles effortlessly into crevices and corners that a brush can’t reach. It’s no wonder DIYers routinely choose cans of aerosol paint for small to medium-size projects.
If it sounds like I prefer spraying to brushing, I do. That’s partly because I spent years applying furniture finishes in a spray booth. These days I no longer have a spray booth, and I only own a handheld airless sprayer for outdoor projects. So I frequently use aerosol cans, just like you.
I’ve found aerosols give great results if used properly. Several years ago I refinished a black lacquer dining room table with spray cans. The results were spectacular, and the finish stood the test of time.
For best results, apply more than one coat and scuff in sand between coats. To do that properly, you’ll need to understand drying times, because they vary from product to product.
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Spray Paint Drying Time vs. Curing Time: Knowing the Difference
All paints, even those in cans, need pigments for color and binders that harden when exposed to air. The pigments and binders need to be suspended in liquid solvents to make them sprayable.
After spraying, paint dries when the solvents evaporate and cures when the binders harden. These are distinct processes that take different amounts of time.
- Drying: Drying takes a matter of minutes when you use spray cans, because the solvents are volatile and evaporate quickly. With an airless sprayer, the solvents used to thin the paint — water or mineral spirits — aren’t as volatile, so drying time is longer, as much as an hour or two. When you spray with a compressed air gun, you need a much thinner material than for an airless sprayer. So it typically dries in 30 minutes to an hour, especially if you thin with a volatile solvent.
- Curing: Alkyds, acrylics and polyurethanes, all common paint binders, are polymers that need time to cross-link. That can take from one hour to several days. Once cross-linking occurs, these finishes are as hard as they will ever be and can’t be softened again.
- Lacquer and shellac: Not all sprayable paints need to cure. Lacquer and shellac are known as drying finishes because they harden as they dry. But they don’t cross-link, so they be re-softened with thinner or fresh material. Nevertheless, a lacquer or shellac finish still takes a few hours to become hard enough to use.
Factors Affecting Spray Paint Drying Time
While the type of solvent in the paint is one of the main determinants of drying time, there are others:
- Humidity: Paint dries quicker in low humidity, especially if it’s water-based. Some finishes — particularly lacquer — can turn cloudy in high humidity, especially if the temperature is low
- Thickness of coat: It takes longer for a thick coat of spray paint to dry than a thin coat. Most pros spray several thin coats rather than a single thick coat to avoid problems from slow drying, such as clouding and dust buildup on the surface of the paint.
- Temperature: Paint dries faster in warm temperatures. But if it’s too warm, the paint can dry too fast and crack or turn powdery. Besides slowing down drying, cold temperatures contribute to clouding.
- Ventilation: Paint dries more quickly in well-ventilated conditions. The fan running in my old spray booth made the paint I sprayed dry in minutes, If you’re painting indoors, keep windows open and/or run a fan to create circulation in the room and exhaust fumes outdoors. It will shorten drying times considerably. On sunny days, take your work outdoors.
- Surface texture: Paint dries more quickly on smooth surfaces than on textured ones.
How Long Does Spray Paint Take To Dry?
Remember, there’s a difference between drying time and curing time. Most spray paint dries in less than an hour in ideal conditions. But if it hasn’t cured yet, you’ll have to wait longer before stacking painted pieces or placing heavy objects on them.
Here are some common wait times at room temperature (65 to 75 degrees) and normal humidity (40% to 60%):
- Solvent-borne acrylic: Dry in one hour; recoat in two hours; stack in 24 to 48 hours.
- Water-borne acrylic: Dry in 30 minutes to an hour; recoat in two hours; stack in 12 to 24 hours.
- Solvent-borne polyurethane: Dry in about an hour; recoat in two hours; stack in two to four days.
- Water-borne polyurethane: Dry in about 30 minutes; recoat in one to two hours; stack in two to four days.
- Spray epoxy: Dry in two to four hours; recoat in four to six hours; stack in 24 to 48 hours.
Signs Spray Paint Is Completely Dry
You can generally tell paint is dry enough to scuff and recoat when no part of the painted surface feels tacky. Paint tends to have a slick appearance when it’s wet, and it turns slightly duller when it dries. So visually, you can tell a painted surface is ready for recoating when it has a uniform dull appearance.
If you’re still unsure, follow the specifications on the product label.
Can You Speed Up the Spray Paint Drying Process?
Yes. If you’re using a spray gun, you can thin the paint with an additive to hasten drying. Japan drier, which is mostly naphtha, is recommended for solvent-based paints. Denatured alcohol is best for water-based ones.
You can’t mix anything into aerosol spray cans, of course. If that’s what you’re using, you’ll need raise the temperature in the surroundings (with heaters if necessary), provide plenty of air circulation with open windows or fans, and spray thin coats.