No matter how great a woodworker you are, sometimes mistakes happen. What do you do to fix them? A screw can go into the wrong place, timber movement creates a crack, or your chisel slips when cutting.
Amongst hundreds of other possibilities, these are all examples of mistakes that can be covered by wood filler (not to be confused with wood putty). If you want to learn about wood filler and how long it takes to dry, continue reading.
How Long Does Wood Filler Take to Dry?
The length of time wood filler takes to dry depends on a couple of factors. The first is temperature and the second is the amount of wood filler applied. Other variables include the brand of filler and the amount of hardener used in a 2-part filler.
However, as a general rule, small amounts of filler in shallow applications take around 2 hours to dry. In larger, unfavorable conditions, a filler can take 24 hours or more to dry.
Sample Wood Filler Drying Times
In this table, we’ve listed some of the most popular filler brands and their drying times, so you can find the one that is right for you.
| Brand | Drying Time |
| Ronseal Multipurpose Wood Filler Natural | Approximately 2 hours |
| Ronseal High Performance Wood Filler | Approximately 30 minutes |
| Osmo interior wood filler | Approximately 30 minutes |
| Morrells Two-Part Coloured Wood Fillers | Approximately 15 minutes |
| Liberon Wood Filler | Approximately 2 hours |
| Sadolin Wood Filler | Approximately 2 hours |
How Long Should You Wait for Wood Filler to Dry Before Painting Over It?
Wood filler must completely dry and cure before it can be painted.
If it isn’t completely free of moisture before the paint seals over the filler, the moisture will cause the paint to bubble. Alongside this, it will be more challenging to get a consistent, crisp finish over the wet filler as the paint will not take to it so well.
Drying time before painting depends on a few factors, which we’ll cover later in this article. It’s essential to check the filler first; drying times are only a guide. You should inspect the filler before applying paint, even if it is well past the expected drying time.
In most circumstances, before painting, you should sand wood filler to create a completely flush surface. If the filler sands well and doesn’t crumble away, you have a good indication that paint can be applied.
Does Wood Filler Harden?
You get two types of wood filler, 1-part, and 2-part.
One-part filler is a pot that contains the filler altogether. The ingredients are mixed, and you scoop the required amount out and apply it to the damaged area. With time, the 1-part filler will harden off and cure.
Two-part fillers are slightly different to 1-part. The main mixture and a hardening agent are within the containers of a 2-part filler. A small amount of hardening agent must get added and thoroughly blended into the main mix. Without the hardener, the mixture does not dry and cure properly.
4 Things Affecting Wood Filler Drying Time
There are a few variables that impact wood filler drying time. In this section, we’ll describe the most important.
1. Environmental Temperature
The warmer the environment, the faster the wood filler will dry. In cold climates, the drying time can be significantly slower as well.
2. Moisture Content
The moisture within the wood will also affect the time it takes for the filler to dry. Some fillers are water-based, they are particularly impacted by moisture content. If too much water is in the wood, it will react with the water-based filler, preventing it from drying quickly.
3. Amount of Filler
The amount of filler used can impact the drying time as well. However, if the filler is spread very thinly, then the drying time is not affected as much.
If the filler is to be applied in a deep fissure, then the drying time is significantly increased. This is because only a small amount of the total volume of the filler is in direct contact with the air.
4. Ventilation
The more ventilation there is in a room, the better. Air is needed to move the moisture away from the surface of the filler. If there is no airflow, it is harder for the moisture to escape the filler.
How to Speed Up Wood Filler Drying Time
Speeding up wood filler drying time is possible. There are a couple of tricks to this process, but it is mainly about controlling the environment. It is important not to speed the drying process up too much. If filler dries too quickly, it can crack and crumble away.
1. Use a Heat Gun
This technique must be used carefully as it can backfire. If you are applying a small, shallow amount of filler, you can try drying it with a heat gun. To do this, quickly move the heat gun repeatedly over the area, and do not stop moving it. A lot of the time, you will see the shade of the filler get lighter as the moisture leaves it.
Be careful not to scorch the material you are working with. Alongside this, if there is too much filler or it is dried too quickly, it will crack and crumble away.
2. Use More Hardener
There is a recommended amount of hardener on a 2-part filler’s packaging. In some circumstances, you can increase this slightly to make the filler dry faster.
When doing this technique, only mix a small amount of filler at a time because a large amount will harden off before you can apply it.
3. Fill Large Gaps in Stages
It’s very tempting to put a large amount of filler into a big gap and call the job done. However, the filler at the bottom of this gap sometimes won’t dry because moisture can’t escape. If this happens, when you come to sand the filler, it will crumble away. You will then have to reapply the filler and start again.
Instead, fill significant gaps in stages, let the first application dry and then apply more. This might seem like a long process, but it will save you time overall.
4. Increase the Room Temperature
If you are working inside and there is heating, turn it up. Perhaps the thermostat can be used. Or, if you are in a workshop, maybe there’s a blow heater that can be turned up. The higher temperature will speed up drying time.
5. Use a Fast-Drying Filler
Some fillers will dry a lot faster than others. Look at the drying times of the fillers you could use, ensure they are suitable for your application, and choose the one that dries the quickest.
6. Use a Fan
Washing dries well outside on a windy day, similar to how airflow improves the drying time of filler. To increase airflow, use a fan and point it, so the air runs over the filler.
Summary
Wood filler drying time is very variable, depending on the type of filler and environmental factors. It can be very tempting to rush the process, but if you speed it up too much, you’re in danger of damaging the filler and repeating the process.
Wood is a natural material that can’t always be rushed, even with modern techniques and products. Be patient, follow the instructions, and observe the filler closely.
You might also want to learn how long Bondo takes to dry and how long wood putty takes to dry.