If you want a good paint job, you need to make sure the paint dries thoroughly and completely before disturbing it. So how long does oil based paint take to dry? And how long does it take oil based primer to dry?
It varies depending on the paint formula and the temperature, but it typically takes 8 hours for oil based paint to dry. The general time can range from 2-24 hours, so it’s best to check your instruction label for your paint’s specifics. Oil based primer can be ready for a topcoat within 1-2 hours, but that may or may not be what you mean by dry time.
Be careful about handling time vs drying time and recoat time
One problem we run into is we don’t always mean the same thing when we say “dry.” Typically you can apply a second coat before the first coat is completely dry. The optimal time for that can be much shorter than the dry time, sometimes 1-2 hours. Often if you miss that 1-2 hour recoat time, you need to wait 24 hours to apply a second coat. Otherwise the two coats can react and wrinkle.
That’s also why the instructions may make it sound like oil based primer dries faster than paint. It doesn’t, but you’re more concerned about recoat time than handling time.
Handling time is the length of time it takes for the piece to be safe to use again. The paint may not be 100% cured, but you can touch it without paint getting on you. At this stage the paint may feel a bit tacky to the touch. That’s the tell tale sign the paint hasn’t reached full strength yet.
Finally, there’s the time it takes for the paint to fully cure and harden. This is usually a longer period of time.
How to make oil based paint dry faster
The general guidance of an 8 hour dry time is based on a comfortable temperature of 70 degrees Fahrenheit/20 degrees Celsius. The minimum temperature you can paint is around 50 degrees Fahrenheit/10 degrees Celsius. Paint dries very slowly at temperatures below that, a trick I take advantage of to keep paint brushes from drying out when I can’t clean them immediately. You may have learned in high school chemistry that every 10 degrees you raise the temperature, you double the speed of a chemical reaction. And even 10 degrees you lower the temperature halves the speed of the reaction. So at 60 degrees, that 8 hour dry time jumps to 16 hours. And at 50 degrees, it jumps to 32. As you can see, painting at the recommended minimum temperature is pushing it.
Oil based paint dries faster at higher temperatures. I once painted a house in July, when the temperature was pushing 100 degrees (40 degrees Celsius). At that temperature, the 8 hour dry time drops to 2 hours. Painting in the dead of summer makes paint dry much faster.
Baking oil-based paint to make it dry faster
Auto body shops and hobbyists will bake paint to make it fully cure faster. Even faster than a July afternoon in St. Louis. A too-high temperature will cause the paint to peel off, but you can bake most oil based paints at temperatures from 140 to 200 degrees Fahrenheit/60 to 90 degrees Celsius to cut drying times. Check your instructions, as some paints can go higher than that. Of course, the item you’re baking also needs to be able to withstand that temperature. Don’t bake plastic at a temperature much higher than 140 degrees Fahrenheit or 60 degrees Celsius.
Commercial shops have paint ovens for this. You can use a household oven, but don’t use the same oven you use for food preparation. Chemicals from the paint can make their way into your food if you do that. I have an old toaster oven I use to bake small projects. For larger projects, it’s more practical to rig up a wooden box large enough to hold the item and put incandescent bulbs in it, trying different wattages of bulbs to achieve the temperature you want.
I know of someone who covers his projects and lets them dry for 1-2 weeks in between coats to let the paint fully cure at room temperature. This works well if you have the patience for it.
How long does oil based primer take to dry?
The length of time for oil based primer to dry is similar to paint. The difference is since you will be applying a coat of paint over the primer, that recoat window is crucial. That’s why the paint can will frequently tell you to apply a coat within a couple of hours or wait 24 hours.
The primer doesn’t fully cure all that much faster than paint, but with primer, the recoat time is just as crucial as the handling time. Possibly more so.
Be sure to double check the instructions on the can, but if you’re painting a house in the dead of summer and you need to prime because you’re making a major color change, you may end up needing to prime one wall, then come right back around and apply the topcoat. The primer could be ready by the time you’ve finished covering the wall.